Muscular System

Topic: Muscles of Anterior Abdominal Wall
Subtopic: Nerve Supply of Pyramidalis Muscle

Keyword Definitions:

• Pyramidalis: A small triangular muscle anterior to the rectus abdominis that tenses the linea alba.

• Rectus Sheath: Fibrous covering formed by aponeuroses of abdominal muscles enclosing rectus abdominis and pyramidalis.

• Subcostal Nerve: Twelfth thoracic spinal nerve supplying muscles of abdominal wall and overlying skin.

• Iliohypogastric Nerve: Arises from L1, supplying skin above pubis and lower abdominal muscles.

• Ilioinguinal Nerve: Branch of L1 nerve that supplies the groin region and upper thigh skin.

• Genitofemoral Nerve: From L1–L2, divides into genital and femoral branches for cremaster and thigh skin.

Lead Question – 2014
Pyramidalis is supplied by?
a) Subcostal nerve
b) Ilioinguinal nerve
c) Iliohypogastric nerve
d) Genitofemoral nerve

Explanation: The pyramidalis muscle is a small triangular structure in front of the rectus abdominis that tenses the linea alba. It is supplied by the subcostal nerve (T12). It may be absent in some individuals and acts as a surgical landmark for rectus sheath termination. (Answer: a)

1) The rectus sheath encloses all except:
a) Pyramidalis
b) Rectus abdominis
c) Inferior epigastric vessels
d) Transversus abdominis

Explanation: The rectus sheath encloses the rectus abdominis, pyramidalis, and epigastric vessels, but not transversus abdominis, which contributes to its aponeurotic formation. (Answer: d)

2) Linea alba extends between:
a) Xiphoid process and umbilicus
b) Umbilicus and pubic crest
c) Xiphoid process and pubic symphysis
d) Costal margin and iliac crest

Explanation: The linea alba is a fibrous midline raphe extending from the xiphoid process to the pubic symphysis. It is used in surgical incisions because of its avascular nature. (Answer: c)

3) The pyramidalis muscle lies:
a) Behind rectus abdominis
b) In front of rectus abdominis
c) Between rectus and transversus abdominis
d) Deep to linea alba

Explanation: The pyramidalis muscle lies anterior to rectus abdominis within the rectus sheath. It helps tense the linea alba and may be absent in some people. (Answer: b)

4) The subcostal nerve is the:
a) T11 nerve
b) T12 nerve
c) L1 nerve
d) L2 nerve

Explanation: The subcostal nerve is derived from the ventral ramus of the twelfth thoracic nerve (T12). It supplies muscles and skin of the anterior abdominal wall. (Answer: b)

5) Which of the following muscles flexes the trunk and stabilizes the pelvis?
a) Pyramidalis
b) Rectus abdominis
c) Transversus abdominis
d) External oblique

Explanation: The rectus abdominis flexes the vertebral column, stabilizes the pelvis, and compresses abdominal viscera. (Answer: b)

6) (Clinical) A 38-year-old man undergoes abdominal surgery. A small triangular muscle anterior to rectus abdominis is identified. Its nerve supply is from:
a) Ilioinguinal nerve
b) Subcostal nerve
c) Genitofemoral nerve
d) Femoral nerve

Explanation: The pyramidalis muscle is supplied by the subcostal nerve (T12) and serves as a landmark for lower rectus sheath termination. (Answer: b)

7) (Clinical) A midline incision through the linea alba is preferred because it is:
a) Highly vascular
b) Avascular
c) Thick and muscular
d) Contains major nerves

Explanation: The linea alba is an avascular fibrous raphe, which allows midline surgical incisions with minimal bleeding. (Answer: b)

8) (Clinical) A surgeon finds absence of pyramidalis during laparotomy. This indicates:
a) Nerve injury
b) Congenital absence (normal variant)
c) Muscle atrophy
d) Hernia risk

Explanation: The pyramidalis is sometimes congenitally absent. It is a normal anatomical variant and not clinically significant. (Answer: b)

9) (Clinical) During cesarean section, incision is taken in the linea alba because:
a) It has abundant blood vessels
b) It has fewer nerves and vessels
c) It provides muscle access
d) It prevents scar formation

Explanation: The linea alba is chosen for surgical incisions because it is avascular and less painful, providing direct access to the abdominal cavity. (Answer: b)

10) (Clinical) The pyramidalis muscle helps the surgeon identify:
a) Inguinal canal
b) Lower rectus sheath
c) Umbilicus
d) Pubic tubercle

Explanation: The pyramidalis muscle marks the lower end of the rectus sheath near the pubic symphysis and is used as a landmark during abdominal surgeries. (Answer: b)

Topic: Fascia and Muscular Insertions
Subtopic: Iliotibial Tract

Keyword Definitions:

• Iliotibial tract: Thickened lateral band of fascia lata extending from iliac crest to lateral condyle of tibia.

• Gluteus maximus: Largest gluteal muscle inserting partly into iliotibial tract, aiding hip extension and lateral stability.

• Fascia lata: Deep fascia of thigh enclosing muscles and forming iliotibial tract laterally.

• Lateral tibial condyle: Outer condyle of tibia where iliotibial tract inserts, providing lateral knee stabilization.

Lead Question - 2014

True about iliotibial tract all except?
a) Receives insertion of gluteus maximus
b) Derived from fascia lata
c) Inserted on lateral tibial condyle
d) None

Explanation: The iliotibial tract is a thickened lateral band of fascia lata. It receives insertion from both gluteus maximus and tensor fasciae latae and inserts on the lateral tibial condyle (Gerdy’s tubercle). All statements are true, so the correct answer is d) None. Clinical importance lies in stabilizing the lateral knee.

Guessed Questions for NEET PG

1) Iliotibial tract inserts at:
a) Medial tibial condyle
b) Lateral tibial condyle
c) Femoral condyle
d) Patella
Explanation: The iliotibial tract inserts on the lateral tibial condyle at Gerdy’s tubercle, stabilizing the knee joint laterally. Correct answer: b) Lateral tibial condyle.

2) Muscle contributing to iliotibial tract is:
a) Gluteus medius
b) Sartorius
c) Tensor fasciae latae
d) Pectineus
Explanation: Tensor fasciae latae contributes fibers to the iliotibial tract, helping in hip abduction and medial rotation. Correct answer: c) Tensor fasciae latae.

3) Iliotibial band syndrome commonly affects:
a) Swimmers
b) Cyclists
c) Runners
d) Weightlifters
Explanation: Iliotibial band syndrome is an overuse injury commonly affecting runners due to repetitive friction over the lateral femoral condyle. Correct answer: c) Runners.

4) Iliotibial tract is a thickening of:
a) Crural fascia
b) Fascia lata
c) Scarpa’s fascia
d) Camper’s fascia
Explanation: The iliotibial tract is a specialized thickened band of fascia lata along the lateral thigh. Correct answer: b) Fascia lata.

5) Iliotibial tract stabilizes which joint?
a) Hip
b) Knee
c) Ankle
d) Shoulder
Explanation: The iliotibial tract stabilizes both hip and knee joints, particularly the lateral knee during walking and running. Correct answer: b) Knee.

6) A marathon runner complains of lateral knee pain, most likely diagnosis?
a) Meniscal tear
b) Iliotibial band syndrome
c) ACL injury
d) PCL injury
Explanation: Lateral knee pain in long-distance runners is often due to iliotibial band friction syndrome. Correct answer: b) Iliotibial band syndrome.

7) Iliotibial tract extends from:
a) Iliac crest to medial tibial condyle
b) Iliac crest to lateral tibial condyle
c) Ischium to patella
d) Femoral shaft to tibia
Explanation: Iliotibial tract extends from iliac crest to lateral tibial condyle (Gerdy’s tubercle). Correct answer: b) Iliac crest to lateral tibial condyle.

8) Which test assesses iliotibial band tightness?
a) Lachman test
b) Ober’s test
c) McMurray test
d) Thompson test
Explanation: Ober’s test is used clinically to check iliotibial band tightness. Correct answer: b) Ober’s test.

9) The iliotibial tract is thickest at:
a) Thigh
b) Leg
c) Foot
d) Knee joint line
Explanation: The iliotibial tract is thickest along the lateral thigh where it descends to insert on the tibia. Correct answer: a) Thigh.

10) Iliotibial tract aids gluteus maximus in:
a) Hip flexion
b) Hip extension
c) Knee flexion
d) Ankle plantarflexion
Explanation: The iliotibial tract transmits the action of gluteus maximus for hip extension and lateral stabilization. Correct answer: b) Hip extension.

Topic: Lower Limb Muscles
Subtopic: Dorsiflexors of Foot

Keyword Definitions:

• Dorsiflexion: Movement of the foot upward at the ankle joint, bringing the toes closer to the shin.

• Tibialis anterior: Primary dorsiflexor of the foot, also inverts the foot.

• Tibialis posterior: Muscle that plantarflexes and inverts the foot.

• Peroneus brevis: Muscle that everts and weakly plantarflexes the foot.

• Extensor digitorum brevis: Muscle on the dorsum of the foot, extends toes but does not dorsiflex significantly.

Lead Question - 2014

Which of the following dorsiflexes the foot?

a) Tibialis posterior
b) Tibialis anterior
c) Peroneus brevis
d) Extensor digitorum brevis

Explanation: Tibialis anterior is the chief dorsiflexor of the foot. It originates from the lateral tibia and inserts on the medial cuneiform and first metatarsal, allowing dorsiflexion and inversion. Other muscles listed do not act as strong dorsiflexors. Correct answer: b) Tibialis anterior.

Guessed Questions for NEET PG

1) Tibialis anterior inserts on?

a) Calcaneum
b) Navicular
c) Medial cuneiform and base of 1st metatarsal
d) Cuboid

Explanation: Tibialis anterior inserts on the medial cuneiform and base of the first metatarsal. This allows it to dorsiflex and invert the foot effectively. Correct answer: c) Medial cuneiform and base of 1st metatarsal.

2) Clinical: A patient with foot drop most likely has paralysis of?

a) Tibialis posterior
b) Tibialis anterior
c) Peroneus longus
d) Soleus

Explanation: Foot drop occurs due to paralysis of dorsiflexors, particularly tibialis anterior, commonly from damage to the common peroneal nerve. Correct answer: b) Tibialis anterior.

3) Which nerve innervates tibialis anterior?

a) Tibial nerve
b) Deep peroneal nerve
c) Superficial peroneal nerve
d) Femoral nerve

Explanation: Tibialis anterior is supplied by the deep peroneal nerve, a branch of the common peroneal nerve. This ensures dorsiflexion of the foot. Correct answer: b) Deep peroneal nerve.

4) Clinical: Weak dorsiflexion with sensory loss between first and second toe suggests injury to?

a) Tibial nerve
b) Deep peroneal nerve
c) Superficial peroneal nerve
d) Sural nerve

Explanation: The deep peroneal nerve supplies tibialis anterior and provides cutaneous sensation to the web between the first and second toes. Its injury causes weakness of dorsiflexion and sensory loss. Correct answer: b) Deep peroneal nerve.

5) Which movement is opposed by tibialis anterior?

a) Plantarflexion
b) Inversion
c) Eversion
d) Dorsiflexion

Explanation: Tibialis anterior causes dorsiflexion and inversion of the foot. It works against plantarflexion and eversion. Correct answer: a) Plantarflexion.

6) Clinical: Steppage gait is seen in lesions of?

a) Superficial peroneal nerve
b) Tibial nerve
c) Common peroneal nerve
d) Femoral nerve

Explanation: Steppage gait occurs in common peroneal nerve injury, due to paralysis of dorsiflexors like tibialis anterior. The patient lifts the leg high to prevent toe dragging. Correct answer: c) Common peroneal nerve.

7) Which of the following is NOT a dorsiflexor?

a) Extensor digitorum longus
b) Extensor hallucis longus
c) Tibialis posterior
d) Tibialis anterior

Explanation: Tibialis posterior is a plantarflexor and invertor, not a dorsiflexor. Other listed muscles dorsiflex the foot. Correct answer: c) Tibialis posterior.

8) Clinical: Which muscle is tested when patient is asked to dorsiflex and invert the foot against resistance?

a) Tibialis anterior
b) Tibialis posterior
c) Peroneus tertius
d) Soleus

Explanation: Dorsiflexion with inversion specifically tests tibialis anterior function, as it is the main muscle performing these combined actions. Correct answer: a) Tibialis anterior.

9) Clinical: Trauma to the lateral aspect of the knee may cause loss of dorsiflexion due to injury to?

a) Femoral nerve
b) Common peroneal nerve
c) Tibial nerve
d) Obturator nerve

Explanation: The common peroneal nerve winds around the neck of fibula, making it vulnerable to trauma. Its injury leads to foot drop from dorsiflexor paralysis. Correct answer: b) Common peroneal nerve.

10) Main action of tibialis anterior?

a) Plantarflexion and eversion
b) Dorsiflexion and inversion
c) Plantarflexion and inversion
d) Dorsiflexion and eversion

Explanation: Tibialis anterior produces dorsiflexion and inversion. It pulls the foot upwards and medially, crucial for normal gait. Correct answer: b) Dorsiflexion and inversion.

Topic: Shoulder Joint
Subtopic: Intracapsular but Extrasynovial Structures

Keyword Definitions:

• Intracapsular: Located within the fibrous capsule of a joint.

• Extrasynovial: Outside the synovial membrane but still within the joint capsule.

• Shoulder joint: A synovial ball-and-socket joint formed between the humerus and scapula.

• Biceps tendon: The long head passes through the shoulder joint capsule but remains extrasynovial.

• Triceps tendon: Attaches posteriorly, not intracapsular.

Lead Question - 2014

Intracapsular but extrasynovial is ?

a) Long head of triceps
b) Long head of biceps
c) Short head of biceps
d) Medial head of biceps

Explanation: The long head of biceps tendon lies within the capsule of the shoulder joint but remains outside the synovial cavity, making it intracapsular but extrasynovial. This feature protects the tendon while maintaining joint mobility. Correct answer is Long head of biceps.

Guessed Questions:

1) Which tendon passes through the intertubercular sulcus of the humerus?

a) Short head of biceps
b) Long head of biceps
c) Coracobrachialis
d) Teres major

Explanation: The long head of biceps tendon passes through the intertubercular sulcus and is held in place by the transverse humeral ligament. This orientation stabilizes the tendon during shoulder movement. Correct answer is Long head of biceps.

2) Which structure prevents dislocation of the long head of biceps tendon?

a) Glenoid labrum
b) Transverse humeral ligament
c) Rotator cuff
d) Deltoid muscle

Explanation: The transverse humeral ligament bridges across the intertubercular sulcus, preventing displacement of the long head of biceps tendon during arm movements. Correct answer is Transverse humeral ligament.

3) A 30-year-old man presents with shoulder pain. MRI reveals inflammation of the tendon passing through the intertubercular sulcus. Which tendon is affected?

a) Subscapularis
b) Long head of biceps
c) Supraspinatus
d) Coracobrachialis

Explanation: Bicipital tendinitis occurs due to inflammation of the long head of biceps tendon within the intertubercular sulcus. It often presents as anterior shoulder pain aggravated by flexion. Correct answer is Long head of biceps.

4) Which part of the glenoid labrum is attached to the long head of biceps tendon?

a) Inferior
b) Superior
c) Anterior
d) Posterior

Explanation: The long head of biceps tendon originates from the supraglenoid tubercle and the superior part of the glenoid labrum, helping stabilize the shoulder joint. Correct answer is Superior.

5) Intracapsular but extrasynovial tendon in the knee joint is?

a) Posterior cruciate ligament
b) Anterior cruciate ligament
c) Patellar ligament
d) Medial collateral ligament

Explanation: The cruciate ligaments (ACL and PCL) are located within the joint capsule but remain extrasynovial. This anatomical arrangement protects them from direct synovial exposure. Correct answer is Anterior cruciate ligament.

6) A patient develops rupture of intracapsular but extrasynovial tendon in the shoulder joint. Which movement will be most affected?

a) Shoulder abduction
b) Shoulder extension
c) Shoulder flexion
d) Shoulder adduction

Explanation: The long head of biceps assists in flexion of the shoulder joint. Rupture of this tendon leads to weakness of flexion and supination, particularly affecting overhead movements. Correct answer is Shoulder flexion.

7) The tendon of long head of biceps is enclosed in a synovial sheath. True or False?

a) True
b) False

Explanation: The long head of biceps tendon has a tubular synovial sheath, facilitating smooth gliding within the intertubercular sulcus during arm movements. Correct answer is True.

8) Which tendon rupture causes “Popeye deformity” in the arm?

a) Short head of biceps
b) Long head of biceps
c) Brachialis
d) Coracobrachialis

Explanation: Rupture of the long head of biceps tendon leads to distal bunching of the muscle belly, producing the “Popeye deformity.” It usually occurs in older adults or athletes. Correct answer is Long head of biceps.

9) Which tendon runs intracapsular in shoulder joint but remains extrasynovial?

a) Long head of triceps
b) Long head of biceps
c) Supraspinatus
d) Teres minor

Explanation: The long head of biceps tendon is the only tendon that lies intracapsular but remains extrasynovial in the shoulder joint. Correct answer is Long head of biceps.

10) Which structure keeps the tendon of long head of biceps in place during shoulder motion?

a) Coracohumeral ligament
b) Transverse humeral ligament
c) Glenohumeral ligament
d) Rotator cuff tendons

Explanation: The transverse humeral ligament stabilizes the long head of biceps tendon in the intertubercular sulcus, preventing its displacement during shoulder movements. Correct answer is Transverse humeral ligament.

Topic: Upper Limb Nerves
Subtopic: Median Nerve and Branches

Keyword Definitions:

• Anterior interosseous nerve: A branch of the median nerve, supplying deep flexors of the forearm and pronator quadratus.

• Median nerve: Formed by medial and lateral cords, supplies most forearm flexors and hand muscles.

• Radial nerve: A major nerve of the posterior arm, supplying extensors of the forearm and hand.

• Ulnar nerve: Supplies intrinsic hand muscles and some forearm flexors.

• Axillary nerve: Supplies deltoid and teres minor muscles, and shoulder sensation.

Lead Question - 2014

Anterior interosseous nerve is a branch of?

a) Radial nerve
b) Median nerve
c) Ulnar nerve
d) Axillary nerve

Explanation: The anterior interosseous nerve arises from the median nerve just below the elbow. It supplies flexor pollicis longus, lateral half of flexor digitorum profundus, and pronator quadratus. It does not provide cutaneous innervation. Therefore, the correct answer is Median nerve, which gives this important motor branch.

Guessed Questions

1. The anterior interosseous nerve supplies all except?

a) Flexor pollicis longus
b) Pronator quadratus
c) Flexor digitorum superficialis
d) Flexor digitorum profundus (lateral half)

Explanation: The anterior interosseous nerve supplies FPL, pronator quadratus, and the lateral half of FDP. Flexor digitorum superficialis is supplied by the median nerve but not its anterior interosseous branch. Thus, the correct answer is Flexor digitorum superficialis.

2. A patient with anterior interosseous nerve injury is unable to?
a) Flex distal phalanx of thumb
b) Flex proximal phalanx of thumb
c) Extend wrist
d) Abduct thumb

Explanation: Anterior interosseous nerve injury causes weakness in flexor pollicis longus, leading to inability to flex the distal phalanx of the thumb. Proximal flexion is intact, wrist extension involves radial nerve, and thumb abduction involves radial/median nerves. Thus, the correct answer is Flex distal phalanx of thumb.

3. A clinical sign of anterior interosseous nerve palsy is?
a) Ape thumb deformity
b) Hand of benediction
c) Pinch sign
d) Claw hand

Explanation: In anterior interosseous nerve palsy, patients cannot form a tip-to-tip pinch between thumb and index finger due to loss of FPL and FDP function. Instead, they approximate pads of fingers. This is called the Pinch sign, characteristic of AIN injury.

4. The median nerve in the forearm gives rise to?
a) Anterior interosseous nerve
b) Posterior interosseous nerve
c) Musculocutaneous nerve
d) Lateral pectoral nerve

Explanation: The median nerve gives off the anterior interosseous nerve below the elbow. The posterior interosseous is a branch of the radial nerve, musculocutaneous comes from the lateral cord, and lateral pectoral is from the lateral cord. Correct answer is Anterior interosseous nerve.

5. A patient with deep forearm pain and weakness of pinch grip but no sensory loss most likely has -
a) Median nerve lesion
b) Ulnar nerve lesion
c) Anterior interosseous nerve lesion
d) Radial nerve lesion

Explanation: Anterior interosseous nerve is purely motor. Its lesion causes deep forearm pain, loss of pinch grip, but no cutaneous sensory loss. Median and ulnar nerve lesions include sensory changes, radial nerve causes wrist drop. Correct answer is Anterior interosseous nerve lesion.

6. Flexor digitorum profundus is supplied by -
a) Median nerve alone
b) Ulnar nerve alone
c) Median and ulnar nerves
d) Radial nerve

Explanation: Flexor digitorum profundus has dual innervation. Lateral half (index and middle fingers) by anterior interosseous nerve (median), medial half (ring and little fingers) by ulnar nerve. Hence, correct answer is Median and ulnar nerves.

7. The anterior interosseous nerve runs along which artery?
a) Radial artery
b) Anterior interosseous artery
c) Posterior interosseous artery
d) Ulnar artery

Explanation: The anterior interosseous nerve runs on the anterior surface of the interosseous membrane, accompanying the anterior interosseous artery, a branch of the ulnar artery. Correct answer is Anterior interosseous artery.

8. Injury to anterior interosseous nerve affects which movement?
a) Thumb extension
b) Index finger DIP flexion
c) Wrist flexion
d) Elbow extension

Explanation: The anterior interosseous nerve supplies the lateral half of FDP, flexing DIP of index and middle fingers. Injury impairs DIP flexion of index finger. Wrist flexion is preserved by FCR, thumb extension by radial nerve, elbow extension by radial nerve. Correct answer is Index finger DIP flexion.

9. The "OK sign" test is used to diagnose -
a) Ulnar nerve palsy
b) Radial nerve palsy
c) Anterior interosseous nerve palsy
d) Axillary nerve palsy

Explanation: In anterior interosseous nerve palsy, the patient cannot form a circle using thumb and index finger tips, producing a flat "OK sign." This is diagnostic of Anterior interosseous nerve palsy. Other nerve lesions present with different clinical signs.

10. A 40-year-old with forearm fracture develops inability to flex thumb IP and index DIP joints, but no sensory loss. Which nerve is injured?
a) Ulnar nerve
b) Anterior interosseous nerve
c) Radial nerve
d) Musculocutaneous nerve

Explanation: Loss of thumb IP and index DIP flexion with no sensory loss indicates anterior interosseous nerve injury, as it supplies FPL and FDP lateral half. Ulnar nerve causes sensory loss, radial nerve affects extensors, musculocutaneous supplies arm flexors. Correct answer is Anterior interosseous nerve.

Topic: Muscle Physiology

Subtopic: Muscle Contraction and ATPase Activity

Keyword Definitions:

• ATPase: Enzyme that hydrolyzes ATP to release energy for cellular processes.

• Actin: Thin filament protein in muscles interacting with myosin for contraction.

• Myosin: Thick filament protein with intrinsic ATPase activity driving cross-bridge cycling.

• Troponin: Regulatory protein controlling actin-myosin interaction during contraction.

• Cross-bridge cycle: Repetitive interaction between actin and myosin powered by ATP hydrolysis.

Lead Question - 2013

ATPase activity is present in

a) Actin

b) Myosin

c) Troponin

d) None

Explanation: Myosin contains intrinsic ATPase activity in its head domain, which hydrolyzes ATP to provide energy for cross-bridge cycling and muscle contraction. Actin and troponin are structural and regulatory proteins without enzymatic activity. Answer: b) Myosin.

1) Guess Question:

Which part of myosin possesses ATPase activity?

a) Tail region

b) Head region

c) Rod region

d) Light chains

Explanation: The myosin head contains ATPase activity, which hydrolyzes ATP to ADP and inorganic phosphate, providing energy for the power stroke during contraction. Tail and rod regions are structural. Answer: b) Head region.

2) Guess Question:

Which ion binds to troponin to initiate contraction?

a) Sodium

b) Potassium

c) Calcium

d) Magnesium

Explanation: Calcium binds to troponin C, causing conformational change that moves tropomyosin off actin binding sites, allowing myosin heads with ATPase activity to interact. Answer: c) Calcium.

3) Guess Question:

Which process directly uses myosin ATPase activity?

a) Glycolysis

b) Cross-bridge cycling

c) Oxidative phosphorylation

d) Sodium-potassium pump

Explanation: Myosin ATPase provides energy for cross-bridge cycling in muscle contraction, allowing repetitive attachment, pivoting, and detachment from actin. Glycolysis and oxidative phosphorylation generate ATP, while Na+/K+ pump is unrelated. Answer: b) Cross-bridge cycling.

4) Guess Question:

A patient has myopathy with defective myosin ATPase. Expected finding is:

a) Weak muscle contraction

b) Hyperactive reflexes

c) Normal contraction

d) Increased tone

Explanation: Defective myosin ATPase prevents ATP hydrolysis, reducing energy for cross-bridge cycling. This leads to weak muscle contraction, hypotonia, and exercise intolerance. Answer: a) Weak muscle contraction.

5) Guess Question:

Which filament slides during muscle contraction?

a) Myosin

b) Actin

c) Troponin

d) Titin

Explanation: Actin filaments slide past stationary myosin filaments during contraction. Myosin heads use ATPase activity to pull actin. Troponin and titin are regulatory and elastic elements. Answer: b) Actin.

6) Guess Question:

Which molecule inhibits actin-myosin interaction in relaxed muscle?

a) Tropomyosin

b) Troponin

c) ATP

d) Myosin light chain

Explanation: Tropomyosin blocks actin binding sites in relaxed muscle. Troponin regulates tropomyosin movement, ATP energizes myosin head, but the inhibitor of cross-bridge formation is tropomyosin. Answer: a) Tropomyosin.

7) Guess Question:

Which compound directly provides energy for myosin ATPase?

a) ADP

b) AMP

c) ATP

d) GTP

Explanation: ATP binds myosin head and is hydrolyzed by ATPase activity to ADP + Pi, providing energy for the power stroke and detachment. ADP alone does not provide energy. Answer: c) ATP.

8) Guess Question:

A 10-year-old has congenital myopathy with low myosin ATPase activity. Likely symptom is:

a) Delayed muscle contraction

b) Rapid fatigue

c) Weakness

d) All of the above

Explanation: Low myosin ATPase impairs ATP hydrolysis, slowing cross-bridge cycling, reducing force generation, and causing weakness, delayed contraction, and rapid fatigue. Answer: d) All of the above.

9) Guess Question:

Which filament does not have ATPase activity?

a) Myosin

b) Actin

c) Both

d) None

Explanation: Only myosin has ATPase activity. Actin is a structural filament without enzymatic function. Therefore, actin cannot hydrolyze ATP. Answer: b) Actin.

10) Guess Question:

During rigor mortis, ATP is depleted. Effect on myosin ATPase activity is:

a) Increased activity

b) Decreased activity

c) No cross-bridge detachment

d) Enhanced contraction

Explanation: Without ATP, myosin heads cannot detach from actin despite ATPase presence. Cross-bridges remain attached, causing rigidity (rigor mortis). ATP hydrolysis is required for detachment and relaxation. Answer: c) No cross-bridge detachment.

Chapter: Excitable Tissues

Topic: Muscle Physiology

Subtopic: Calcium Channels in Skeletal Muscle

Keyword Definitions:

• Calcium channels: Protein channels that allow Ca²⁺ ions to enter cells, vital for muscle contraction and neurotransmission.

• L-type channels: Long-lasting, high-voltage activated channels predominant in skeletal and cardiac muscles.

• T-type channels: Transient, low-voltage activated channels, important in pacemaker activity.

• N-type channels: Found mainly in neurons, involved in neurotransmitter release.

• R-type channels: Resistant calcium channels, less common physiologically.

Lead Question - 2013

Most common type of calcium channels of skeletal muscles are ?

a) T type

b) L type

c) R type

d) N type

Explanation: Skeletal muscle contraction is mediated by L-type calcium channels located in the transverse tubules. These channels act as voltage sensors and couple with ryanodine receptors on the sarcoplasmic reticulum for Ca²⁺ release. Correct answer: L type.

1) Calcium release from sarcoplasmic reticulum in skeletal muscle is triggered by?

a) L-type calcium channel activation

b) T-type calcium channel activation

c) Sodium channel inactivation

d) Potassium efflux

Explanation: Skeletal muscle contraction depends on L-type calcium channel activation in T-tubules, which mechanically couples with ryanodine receptors, leading to sarcoplasmic reticulum calcium release. Correct answer: L-type calcium channel activation.

2) A patient with mutation in ryanodine receptor shows?

a) Malignant hyperthermia

b) Hypokalemia

c) Myasthenia gravis

d) Hyponatremia

Explanation: Mutations in ryanodine receptors cause uncontrolled calcium release during anesthesia, leading to malignant hyperthermia with rigidity, tachycardia, and hyperthermia. Correct answer: Malignant hyperthermia.

3) In cardiac muscle, the main calcium channel responsible for excitation-contraction coupling is?

a) L-type

b) T-type

c) N-type

d) P-type

Explanation: Cardiac contraction relies on L-type calcium channels, which mediate calcium influx during plateau phase, triggering further calcium-induced calcium release from sarcoplasmic reticulum. Correct answer: L-type.

4) A patient treated with nifedipine. Which calcium channel is blocked?

a) L-type

b) T-type

c) N-type

d) R-type

Explanation: Nifedipine, a dihydropyridine calcium channel blocker, selectively inhibits L-type calcium channels, reducing vascular smooth muscle contraction and lowering blood pressure. Correct answer: L-type.

5) Which calcium channels are important in pacemaker activity of SA node?

a) L-type

b) T-type

c) N-type

d) R-type

Explanation: T-type calcium channels open transiently at low voltage, contributing to the depolarization phase of SA node pacemaker cells. Correct answer: T-type.

6) A child with congenital myopathy shows impaired excitation-contraction coupling. Likely channel defect?

a) L-type calcium channel

b) Sodium channel

c) Potassium channel

d) Chloride channel

Explanation: Excitation-contraction coupling in skeletal muscle depends on L-type calcium channels functioning as voltage sensors. A defect impairs calcium release from SR, leading to muscle weakness. Correct answer: L-type calcium channel.

7) N-type calcium channels are primarily located in?

a) Skeletal muscle

b) Cardiac muscle

c) Neurons

d) Liver cells

Explanation: N-type calcium channels are located in presynaptic terminals of neurons, playing a role in neurotransmitter release. Correct answer: Neurons.

8) In smooth muscle, calcium entry for contraction mainly occurs through?

a) L-type channels

b) N-type channels

c) R-type channels

d) Sodium leak channels

Explanation: Smooth muscle contraction largely depends on calcium influx through L-type calcium channels, which activate calmodulin and MLCK for actin-myosin interaction. Correct answer: L-type.

9) A patient develops synaptic transmission defect with reduced neurotransmitter release. Likely channel defect?

a) N-type calcium channel

b) L-type calcium channel

c) T-type calcium channel

d) R-type calcium channel

Explanation: N-type calcium channels control neurotransmitter release at presynaptic terminals. Dysfunction reduces exocytosis, impairing synaptic communication. Correct answer: N-type calcium channel.

10) Which calcium channel is responsible for prolonged calcium current in cardiac ventricular myocytes?

a) L-type

b) T-type

c) N-type

d) R-type

Explanation: L-type calcium channels mediate long-lasting inward calcium current during plateau phase of cardiac action potential, crucial for contraction. Correct answer: L-type.

11) Skeletal muscle contraction does not depend on extracellular calcium influx because?

a) Direct mechanical coupling of L-type channel with SR ryanodine receptor

b) Sodium channel influx is sufficient

c) Potassium efflux replaces calcium

d) Myosin does not need calcium

Explanation: In skeletal muscle, excitation-contraction coupling occurs by direct mechanical interaction between L-type channels in T-tubules and ryanodine receptors in SR. Thus, extracellular calcium influx is not essential. Correct answer: Direct mechanical coupling.

Topic: Muscle Fiber Types

Subtopic: Characteristics of Red Muscle Fibers

• Red muscle fibers: Muscle fibers rich in myoglobin and mitochondria, adapted for endurance and continuous activity.

• Mitochondria: Organelles responsible for ATP production through oxidative phosphorylation, abundant in endurance muscle fibers.

• Myoglobin: Oxygen-binding protein in muscle cells, increasing oxygen availability for aerobic metabolism, giving red fibers their color.

• Oxidative capacity: The ability of a muscle fiber to generate ATP through aerobic respiration, high in red fibers.

• Glycolytic metabolism: Energy production pathway primarily using anaerobic glycolysis, typical of white muscle fibers.

Lead Question - 2013 (September 2008)

All are true about red muscle fibers except?

• a) More mitochondria

• b) Glycolytic metabolism

• c) More myoglobin

• d) More oxidative capacity

Answer: b) Glycolytic metabolism

Explanation: Red muscle fibers are rich in mitochondria and myoglobin, providing high oxidative capacity for sustained aerobic activities. Their primary metabolism is oxidative phosphorylation, not glycolytic metabolism, which is characteristic of white (fast-twitch) fibers specialized for short bursts of intense activity rather than endurance.

1. Guessed Question

Red muscle fibers are adapted for?

• a) Short bursts of strength

• b) Endurance and continuous aerobic work

• c) Anaerobic metabolism

• d) Rapid fatigue

Answer: b) Endurance and continuous aerobic work

Explanation: Red muscle fibers (Type I) are designed for sustained, low-intensity activities. Their rich myoglobin and mitochondria content facilitate efficient aerobic metabolism, allowing prolonged contraction without fatigue, as seen in postural muscles or endurance sports like marathon running.

2. Guessed Question

Which component gives red muscle fibers their color?

• a) Mitochondria

• b) Hemoglobin

• c) Myoglobin

• d) Glycogen

Answer: c) Myoglobin

Explanation: Myoglobin, an oxygen-binding protein present in high amounts in red muscle fibers, imparts a reddish color. It ensures a steady oxygen supply for aerobic metabolism, critical in endurance activities where sustained muscle contraction depends on continuous oxygen utilization.

3. Guessed Question

High oxidative capacity of red muscle fibers means they:

• a) Generate ATP anaerobically

• b) Depend on glycolysis

• c) Use oxygen for energy

• d) Store less ATP

Answer: c) Use oxygen for energy

Explanation: Red muscle fibers possess high oxidative capacity due to abundant mitochondria and myoglobin. This enables efficient ATP production via aerobic respiration, ideal for sustained activities, contrasting with white fibers relying more on anaerobic glycolysis for quick, powerful actions.

4. Guessed Question

Which muscle fiber type fatigues least?

• a) White fibers

• b) Red fibers

• c) Type IIb fibers

• d) Fast-twitch fibers

Answer: b) Red fibers

Explanation: Red fibers (Type I) are fatigue-resistant because of their high mitochondria and myoglobin content. These features support continuous ATP production through aerobic pathways, ideal for long-duration, low-intensity tasks, such as maintaining posture or endurance running.

5. Guessed Question

Which fiber type primarily performs anaerobic work?

• a) Red fibers

• b) Type I fibers

• c) White fibers

• d) Cardiac fibers

Answer: c) White fibers

Explanation: White fibers (Type IIb) have fewer mitochondria and rely on anaerobic glycolysis for energy production. They provide rapid, powerful contractions for short durations but fatigue quickly, unlike red fibers, which sustain prolonged aerobic work.

6. Guessed Question

High myoglobin content in red fibers facilitates?

• a) Anaerobic metabolism

• b) Oxygen storage and delivery

• c) Rapid contraction

• d) Low ATP production

Answer: b) Oxygen storage and delivery

Explanation: Myoglobin stores and delivers oxygen within muscle cells, ensuring continuous aerobic metabolism. Red fibers benefit from this high myoglobin concentration, which is crucial for endurance activities, allowing efficient ATP production and preventing fatigue during prolonged muscle use.

7. Guessed Question

Red fibers are abundant in which type of muscle?

• a) Postural muscles

• b) Phasic muscles

• c) Fast-contracting muscles

• d) Digestive smooth muscles

Answer: a) Postural muscles

Explanation: Postural muscles are rich in red fibers to support sustained low-intensity contractions necessary for maintaining body posture. Their high mitochondrial and myoglobin content enable efficient aerobic metabolism, preventing fatigue and ensuring continuous function throughout the day.

8. Guessed Question

Primary role of red muscle fibers is to:

• a) Generate short, intense force

• b) Maintain prolonged contractions

• c) Store glycogen

• d) Control reflex actions

Answer: b) Maintain prolonged contractions

Explanation: Red fibers (Type I) are specialized for prolonged, low-intensity contractions. Their abundant mitochondria and myoglobin support sustained aerobic ATP production, critical for endurance tasks and postural maintenance, differing from white fibers designed for brief, intense efforts.

9. Guessed Question

Which statement is incorrect regarding red muscle fibers?

• a) High mitochondrial content

• b) High myoglobin content

• c) Predominantly glycolytic metabolism

• d) Suited for endurance activities

Answer: c) Predominantly glycolytic metabolism

Explanation: Red muscle fibers do not rely on glycolytic metabolism. Instead, they utilize aerobic oxidative phosphorylation supported by mitochondria and myoglobin, enabling sustained energy production for endurance activities, contrasting with white fibers that use glycolysis for rapid energy.

.

Topic: Muscle Fiber Types

Subtopic: Mitochondrial Content in Muscle Fibers

• Red fibers: Muscle fibers rich in myoglobin and mitochondria, suited for endurance.

• Type I fibers: Slow-twitch fibers, abundant in mitochondria, support sustained contraction and aerobic metabolism.

• White fibers: Fast-twitch fibers with fewer mitochondria, designed for rapid, powerful contractions and anaerobic work.

• Slow fibers: Fibers that contract slowly and are fatigue-resistant due to abundant mitochondria and myoglobin.

Lead Question - 2013 (September 2008)

Less mitochondria are seen in -

• a) Red fibers

• b) Type I fibers

• c) White fibers

• d) Slow fibers

Answer: c) White fibers

Explanation: White fibers (Type IIb) are fast-twitch fibers with fewer mitochondria, optimized for short bursts of high-intensity activities. Their energy is primarily derived from anaerobic glycolysis. These fibers fatigue quickly, making them less suited for endurance activities compared to red or Type I fibers which are mitochondria-rich and support sustained contraction.

1. Guessed Question

Which fibers are rich in mitochondria and support endurance?

• a) White fibers

• b) Type IIb fibers

• c) Red fibers

• d) Fast fibers

Answer: c) Red fibers

Explanation: Red fibers (Type I) are rich in mitochondria and myoglobin, supporting aerobic metabolism and sustained contractions. These fibers are designed for endurance activities, providing resistance to fatigue and enabling prolonged muscle work by efficiently producing ATP through oxidative phosphorylation.

2. Guessed Question

Type I muscle fibers are characterized by?

• a) Rapid fatigue

• b) Low mitochondrial content

• c) High myoglobin content

• d) Anaerobic metabolism

Answer: c) High myoglobin content

Explanation: Type I muscle fibers contain high myoglobin and mitochondrial density, supporting aerobic metabolism and sustained low-force activities. They are slow-twitch fibers that resist fatigue, primarily used in endurance exercises such as marathon running or posture maintenance due to their efficient oxygen utilization and energy production.

3. Guessed Question

Which fiber type is predominantly used in sprinting?

• a) Type I fibers

• b) White fibers

• c) Red fibers

• d) Smooth fibers

Answer: b) White fibers

Explanation: White fibers (Type IIb) are fast-twitch fibers used in activities like sprinting that require rapid, powerful contractions. Due to low mitochondrial content, these fibers rely on anaerobic metabolism, providing energy quickly but with fast fatigue onset, making them ideal for short-term high-intensity efforts.

4. Guessed Question

Primary energy system for white muscle fibers?

• a) Oxidative phosphorylation

• b) Anaerobic glycolysis

• c) Fatty acid oxidation

• d) Creatine phosphate system

Answer: b) Anaerobic glycolysis

Explanation: White fibers depend mainly on anaerobic glycolysis due to their low mitochondrial content. This process allows rapid ATP production without the need for oxygen, enabling short bursts of intense activity, but results in lactic acid accumulation, contributing to quick onset of fatigue.

5. Guessed Question

Which fiber type is slow to fatigue?

• a) Type IIb fibers

• b) White fibers

• c) Type I fibers

• d) Fast fibers

Answer: c) Type I fibers

Explanation: Type I fibers are slow-twitch and fatigue-resistant due to their rich mitochondrial and myoglobin content. They rely on aerobic metabolism for sustained energy, making them ideal for endurance activities such as long-distance running, standing posture, and activities requiring constant low-intensity effort.

6. Guessed Question

White fibers predominantly utilize which metabolic pathway?

• a) Oxidative metabolism

• b) Anaerobic glycolysis

• c) Lipid oxidation

• d) Protein catabolism

Answer: b) Anaerobic glycolysis

Explanation: Due to their limited mitochondria and myoglobin, white fibers (Type IIb) primarily rely on anaerobic glycolysis for ATP production. This enables fast energy supply during high-intensity activities but produces lactic acid, causing rapid fatigue and restricting use in endurance exercises.

7. Guessed Question

Which fiber type is most abundant in postural muscles?

• a) Type IIb fibers

• b) White fibers

• c) Type I fibers

• d) Type IIa fibers

Answer: c) Type I fibers

Explanation: Postural muscles contain predominantly Type I fibers due to their high mitochondrial and myoglobin content, ensuring continuous low-force contractions without fatigue. These fibers are specialized for endurance and maintaining body posture over long periods, sustaining steady force generation through aerobic metabolism.

8. Guessed Question

Which fiber type is referred to as "slow oxidative"?

• a) Type IIb

• b) Type I

• c) Type IIa

• d) White fibers

Answer: b) Type I

Explanation: Type I fibers are termed "slow oxidative" because of their slow contraction speed, rich mitochondrial density, and aerobic metabolism capability. This enables them to sustain prolonged, low-intensity activities and resist fatigue, making them crucial in endurance performance and posture maintenance.

9. Guessed Question

White fibers are primarily used for:

• a) Long-distance running

• b) High-intensity short bursts of activity

• c) Postural control

• d) Low-resistance repetitive work

Answer: b) High-intensity short bursts of activity

Explanation: White fibers (Type IIb) are optimized for short-term, high-intensity work like weightlifting or sprinting. Their low mitochondrial and high glycolytic enzyme content allow rapid ATP generation through anaerobic glycolysis, though they fatigue quickly, unsuitable for sustained activities.

Topic: Muscles of Facial Expression

Subtopic: Orbicularis Oculi and Related Muscles

Keyword Definitions:

• Orbicularis Oculi: Circular muscle around the eye that enables eyelid closure and blinking.

• Levator Labii Superioris: Muscle elevating upper lip; involved in facial expression.

• Corrugator Supercilii: Muscle that draws eyebrows medially and downward, producing frowning.

• Levator Palpebrae Superioris: Muscle responsible for raising the upper eyelid; not involved in winking.

Lead Question - 2013

Which muscle plays a role in winking?

a) Levator labii superioris
b) Orbicularis oculi
c) Corrugator supercilli
d) Levator palpebrae

Explanation: The orbicularis oculi muscle is the primary muscle responsible for eyelid closure and actions like blinking and winking. It encircles the eye and contracts to close the eyelids voluntarily or reflexively. Other listed muscles serve different facial functions. The correct answer is b) Orbicularis oculi.

Guessed Question 2

Which branch of the facial nerve supplies the orbicularis oculi?

a) Temporal
b) Zygomatic
c) Buccal
d) Mandibular

Explanation: The temporal and zygomatic branches of the facial nerve (cranial nerve VII) innervate the orbicularis oculi muscle, controlling eyelid movements such as blinking and winking. These branches are crucial in facial nerve function assessment. Correct answer is a) Temporal and b) Zygomatic.

Guessed Question 3

Paralysis of orbicularis oculi leads to which clinical sign?

a) Lagophthalmos
b) Ptosis
c) Diplopia
d) Strabismus

Explanation: Lagophthalmos refers to incomplete eyelid closure, often seen in facial nerve (VII) palsy affecting the orbicularis oculi. This can lead to exposure keratitis and eye dryness due to impaired blinking. The correct answer is a) Lagophthalmos.

Guessed Question 4

The levator palpebrae superioris is innervated by which nerve?

a) Oculomotor nerve (CN III)
b) Facial nerve (CN VII)
c) Trigeminal nerve (CN V)
d) Accessory nerve (CN XI)

Explanation: The levator palpebrae superioris muscle is innervated by the oculomotor nerve (CN III) and elevates the upper eyelid. Dysfunction may lead to ptosis, but it does not contribute to winking. Correct answer is a) Oculomotor nerve (CN III).

Guessed Question 5

Which of the following muscles is responsible for frowning?

a) Orbicularis oculi
b) Corrugator supercilli
c) Levator labii superioris
d) Levator palpebrae superioris

Explanation: The corrugator supercilli muscle draws the eyebrows medially and downward, creating vertical wrinkles above the nose, producing a frown. Orbicularis oculi closes eyelids but does not produce frown. Correct answer is b) Corrugator supercilli.

Guessed Question 6

In Bell’s palsy, which muscle is typically affected?

a) Orbicularis oculi
b) Sternocleidomastoid
c) Masseter
d) Temporalis

Explanation: Bell’s palsy involves unilateral facial nerve (CN VII) paralysis, impairing the orbicularis oculi. This results in inability to close the eye fully, leading to dryness and risk of keratitis. Other muscles are innervated differently. Correct answer is a) Orbicularis oculi.

Guessed Question 7

Which muscle elevates the upper lip?

a) Orbicularis oculi
b) Levator labii superioris
c) Corrugator supercilli
d) Levator palpebrae superioris

Explanation: The levator labii superioris elevates the upper lip, aiding facial expressions such as smiling or showing disdain. It is not involved in eyelid movements. Correct answer is b) Levator labii superioris.

Guessed Question 8

The orbicularis oculi muscle is divided into which parts?

a) Palpebral and orbital parts
b) Nasal and palpebral parts
c) Orbital and maxillary parts
d) Palpebral and zygomatic parts

Explanation: The orbicularis oculi muscle is composed of two parts: the palpebral part (involved in gentle eyelid closure such as blinking or winking) and the orbital part (responsible for forceful closure of the eyelids). Correct answer is a) Palpebral and orbital parts.

Guessed Question 9

Which artery supplies blood to orbicularis oculi muscle?

a) Facial artery
b) Ophthalmic artery
c) Maxillary artery
d) External carotid artery

Explanation: The ophthalmic artery, a branch of the internal carotid artery, provides blood supply to the orbicularis oculi muscle. It is critical for maintaining eyelid function and ocular surface health. Correct answer is b) Ophthalmic artery.

Guessed Question 10

Which clinical test assesses orbicularis oculi function?

a) Corneal reflex test
b) Visual acuity test
c) Rinne test
d) Weber test

Explanation: The corneal reflex test assesses the sensory and motor components of blinking, evaluating the function of the trigeminal (sensory) and facial (motor to orbicularis oculi) nerves. Lack of eyelid closure indicates dysfunction of the orbicularis oculi. Correct answer is a) Corneal reflex test.

Keyword Definitions

• Hip flexion – Movement decreasing the angle between thigh and trunk.

• Iliopsoas – Primary hip flexor formed by psoas major and iliacus; inserts on lesser trochanter.

• Psoas major – Lumbar-origin muscle (T12–L5) flexing hip; innervated by L1–L3 (direct branches).

• Iliacus – Iliac fossa muscle joining psoas; femoral nerve (L2–L3).

• Rectus femoris – Biarticular quadriceps head; flexes hip, extends knee; origin AIIS.

• Sartorius – ASIS origin; flexes, abducts, laterally rotates hip; flexes knee.

• Tensor fasciae latae (TFL) – Assists hip flexion/abduction; superior gluteal nerve (L4–S1).

• Femoral nerve – L2–L4 nerve to anterior thigh flexors/extensors.

• Thomas test – Assesses fixed flexion deformity of hip/iliopsoas contracture.

• Psoas sign – Pain with resisted hip flexion/extension of hip suggesting psoas irritation (e.g., retrocecal appendicitis).

Chapter: Anatomy / Lower Limb

Topic: Muscles of the Hip

Subtopic: Flexors of the Hip Joint

Lead Question – 2013

Muscle causing flexion of hip ?

a) Biceps femoris

b) Psoas major

c) Gluteus maximus

d) TFL

Explanation: The prime mover for hip flexion is iliopsoas; among options, psoas major is the principal flexor. TFL assists but is not the main flexor. Biceps femoris mainly extends hip and flexes knee; gluteus maximus extends hip. Correct answer: Psoas major.

Guessed Questions for NEET PG

1) Primary insertion site of the main hip flexor complex is?

a) Greater trochanter

b) Lesser trochanter

c) Intertrochanteric line

d) Iliac crest

Explanation: Iliopsoas (psoas major + iliacus) inserts onto the lesser trochanter of the femur via a common tendon, providing a powerful flexion vector across the hip with some external rotation. Correct answer: Lesser trochanter.

2) Nerve supply of iliacus is via?

a) Obturator nerve

b) Femoral nerve

c) Sciatic nerve

d) Superior gluteal nerve

Explanation: Iliacus is innervated by the femoral nerve (L2–L3). In contrast, psoas major receives direct branches from the lumbar plexus (L1–L3). Understanding dual innervation patterns aids clinical localization of weakness. Correct answer: Femoral nerve.

3) A footballer with pain on resisted straight-leg raise; MRI shows AIIS avulsion. Weakness likely in?

a) Hip extension

b) Hip flexion

c) Knee flexion

d) Hip adduction

Explanation: AIIS avulsion implicates rectus femoris origin. Rectus femoris flexes the hip and extends the knee; acute injury produces painful/weak hip flexion on straight-leg raise. Correct answer: Hip flexion.

4) Thomas test detects contracture of which muscle group?

a) Hip abductors

b) Hip extensors

c) Hip flexors (iliopsoas)

d) Hip adductors

Explanation: Thomas test identifies fixed flexion deformity due to tightness/contracture of iliopsoas. The contralateral hip is maximally flexed; lumbar lordosis flattens; a rising contralateral thigh indicates flexor contracture. Correct answer: Hip flexors (iliopsoas).

5) Which muscle is NOT a primary hip flexor?

a) Sartorius

b) Pectineus

c) Gluteus medius

d) Rectus femoris

Explanation: Gluteus medius chiefly abducts and stabilizes pelvis; it is not a hip flexor. Sartorius and rectus femoris flex the hip; pectineus mainly adducts but contributes to flexion. Correct answer: Gluteus medius.

6) Superior gluteal nerve injury most reduces which assisting action at hip?

a) Flexion by TFL

b) Extension by gluteus maximus

c) Adduction by gracilis

d) External rotation by piriformis

Explanation: Superior gluteal nerve (L4–S1) supplies TFL, gluteus medius, and minimus. Injury impairs abduction and internal rotation and reduces TFL-assisted hip flexion. Correct answer: Flexion by TFL.

7) In femoral nerve palsy, which combined movement is most impaired?

a) Hip flexion with knee extension

b) Hip extension with knee flexion

c) Hip adduction with knee flexion

d) Hip abduction with knee extension

Explanation: Femoral nerve supplies iliacus and quadriceps (including rectus femoris). Palsy weakens hip flexion and abolishes knee extension, impairing sit-to-stand and stair climbing. Correct answer: Hip flexion with knee extension.

8) A patient with retrocecal appendicitis has pain on passive extension of right hip. Irritation involves?

a) Gluteus maximus

b) Psoas major

c) Adductor magnus

d) Obturator externus

Explanation: The psoas sign indicates psoas major irritation; stretching the inflamed muscle by hip extension elicits pain. This localizes retroperitoneal inflammation near the psoas. Correct answer: Psoas major.

9) Which root value chiefly powers hip flexion during straight-leg raise?

a) L1

b) L2–L3

c) L4–L5

d) S1–S2

Explanation: Hip flexion strength correlates with L2–L3 myotomes (iliopsoas). Testing resisted hip flexion helps localize radiculopathy to upper lumbar roots. Correct answer: L2–L3.

10) A sprinter has pain at ASIS with weakness in crossing legs. Most likely muscle injured?

a) Sartorius

b) Rectus femoris

c) Pectineus

d) Iliopsoas

Explanation: Sartorius originates at ASIS and flexes, abducts, and laterally rotates the hip—used to cross legs (“tailor’s muscle”). ASIS tenderness with these deficits suggests sartorius strain/avulsion. Correct answer: Sartorius.

Chapter: Anatomy

Topic: Lower Limb

Subtopic: Greater Trochanter and Muscle Attachments

Keyword Definitions:

• Greater Trochanter: A large projection on the lateral upper part of the femur serving as a major muscle attachment site.

• Gluteus Medius: Muscle originating from the outer surface of ilium, inserted into the lateral surface of greater trochanter; chief abductor of hip.

• Gluteus Minimus: Smallest gluteal muscle, inserted into the anterior surface of greater trochanter.

• Piriformis: Muscle from sacrum inserted on the superior border of greater trochanter; external rotator of hip.

• Gluteus Maximus: Largest gluteal muscle inserted mainly into gluteal tuberosity and iliotibial tract.

• Clinical Relevance: Trendelenburg sign occurs when gluteus medius/minimus are weak or damaged.

Lead Question - 2013

Muscle attached to lateral surface of greater trochanter -

a) Gluteus maximus
b) Gluteus medius
c) Gluteus minimus
d) Piriformis

Explanation: The gluteus medius inserts into the lateral surface of the greater trochanter. Gluteus minimus attaches to its anterior surface, and piriformis to its superior border. Gluteus maximus does not insert here. The correct answer is b) Gluteus medius.

Guessed Question 2

Which muscle attaches to the anterior surface of greater trochanter?

a) Gluteus medius
b) Gluteus minimus
c) Piriformis
d) Quadratus femoris

Explanation: Gluteus minimus inserts into the anterior surface of the greater trochanter and works with gluteus medius to abduct and medially rotate the thigh. The correct answer is b) Gluteus minimus.

Guessed Question 3

Piriformis inserts into which part of the greater trochanter?

a) Inferior border
b) Superior border
c) Lateral surface
d) Posterior surface

Explanation: Piriformis muscle, arising from anterior sacrum, inserts into the superior border of the greater trochanter and is an important landmark for gluteal neurovascular structures. The correct answer is b) Superior border.

Guessed Question 4

Damage to the superior gluteal nerve affects which muscle attached to greater trochanter?

a) Gluteus medius
b) Piriformis
c) Quadratus femoris
d) Obturator externus

Explanation: The superior gluteal nerve supplies gluteus medius and minimus. Damage causes Trendelenburg gait due to failure of pelvic stabilization during walking. The correct answer is a) Gluteus medius.

Guessed Question 5

Trendelenburg sign results from paralysis of which muscle?

a) Gluteus medius
b) Gluteus maximus
c) Piriformis
d) Iliopsoas

Explanation: Trendelenburg sign occurs when gluteus medius and minimus (hip abductors inserting on greater trochanter) are weak or paralyzed, leading to pelvic drop on the opposite side. The correct answer is a) Gluteus medius.

Guessed Question 6

A patient with injection injury in gluteal region develops pelvic tilt. Most likely nerve involved?

a) Superior gluteal nerve
b) Inferior gluteal nerve
c) Obturator nerve
d) Sciatic nerve

Explanation: Superior gluteal nerve injury paralyzes gluteus medius and minimus, both attached to the greater trochanter, causing pelvic drop and Trendelenburg gait. The correct answer is a) Superior gluteal nerve.

Guessed Question 7

Which muscle attaching to greater trochanter helps in medial rotation of the hip?

a) Gluteus minimus
b) Piriformis
c) Quadratus femoris
d) Obturator externus

Explanation: Gluteus minimus assists in medial rotation of the thigh at the hip joint, apart from abduction. It inserts on the anterior surface of greater trochanter. The correct answer is a) Gluteus minimus.

Guessed Question 8

In posterior hip dislocation, which muscle attached to greater trochanter is often injured?

a) Piriformis
b) Gluteus medius
c) Quadratus femoris
d) Gluteus maximus

Explanation: In posterior hip dislocation, piriformis and gluteus medius, both attached to greater trochanter, are vulnerable to stretching and tearing due to displacement of femoral head. The correct answer is a) Piriformis.

Guessed Question 9

Which bony prominence serves as an important landmark for intramuscular injections in gluteal region?

a) Greater trochanter
b) Lesser trochanter
c) Ischial spine
d) Iliac crest

Explanation: Greater trochanter is used along with iliac crest to identify safe upper outer quadrant for intramuscular injections in gluteal region, avoiding sciatic nerve. The correct answer is a) Greater trochanter.

Guessed Question 10

Which muscle attaching to greater trochanter is primarily an external rotator of hip?

a) Piriformis
b) Gluteus medius
c) Gluteus minimus
d) Tensor fascia lata

Explanation: Piriformis is primarily an external rotator of the hip joint. It attaches to the superior border of the greater trochanter and is clinically important in piriformis syndrome. The correct answer is a) Piriformis.

Guessed Question 11

Superior gluteal artery damage would compromise blood supply to which muscle attached to greater trochanter?

a) Gluteus medius
b) Piriformis
c) Adductor magnus
d) Quadriceps femoris

Explanation: Superior gluteal artery supplies gluteus medius and minimus, both attached to greater trochanter. Injury reduces blood supply and weakens hip abduction. The correct answer is a) Gluteus medius.

Keyword Definitions

• Gastrocnemius – Superficial, two-headed calf muscle crossing knee and ankle; powerful plantarflexor.

• Soleus – Deep to gastrocnemius, single-headed, plantarflexes ankle (postural muscle).

• Triceps surae – Collective term for gastrocnemius + soleus muscles forming the calf.

• Calcaneal (Achilles) tendon – Common tendon of triceps surae inserting into calcaneus.

• Tibial nerve – Branch of sciatic nerve supplying posterior compartment of leg and plantar foot.

• Plantarflexion – Downward movement of foot at ankle produced by triceps surae.

• Sural nerve – Sensory nerve formed by contributions from tibial and common peroneal nerves; supplies lateral foot.

• Posterior tibial artery – Major artery supplying posterior compartment and plantar foot.

• Baker’s cyst – Popliteal synovial cyst that may compress neurovascular structures in popliteal fossa.

• Achilles tendon rupture – Clinical injury causing inability to plantarflex and toe-raise; Thompson test positive.

Chapter: Anatomy / Lower Limb

Topic: Posterior Compartment of Leg

Subtopic: Triceps Surae (Gastrocnemius & Soleus)

Lead Question – 2013

Which muscles is known as 'Triceps surae'?

a) Gastro-soleus

b) Popliteus

c) EHL

d) EDL

Explanation: “Triceps surae” refers to the gastrocnemius and soleus acting together as the calf complex. Their common insertion via the calcaneal (Achilles) tendon produces powerful plantarflexion. Popliteus, EHL, and EDL are distinct muscles with different functions. Correct answer: Gastro-soleus (triceps surae).

Guessed Questions for NEET PG

1) Which nerve supplies triceps surae?

a) Common peroneal

b) Tibial

c) Femoral

d) Sural

Explanation: Triceps surae (gastrocnemius and soleus) are supplied by the tibial nerve, a branch of the sciatic nerve. Motor fibers reach muscles in the posterior compartment and sensory branches form part of the sural nerve. Correct answer: Tibial nerve. Clinically important in sciatic lesions.

2) The common tendon of triceps surae inserts into the:

a) Navicular

b) Calcaneus

c) Cuboid

d) Talus

Explanation: The calcaneal (Achilles) tendon attaches the triceps surae to the posterior calcaneus. This insertion transmits strong plantarflexor force. Rupture here causes inability to plantarflex and a positive Thompson test. Correct answer: Calcaneus.

3) Thompson test assesses rupture of which structure?

a) Plantaris tendon

b) Calcaneal (Achilles) tendon

c) Tibialis posterior tendon

d) Peroneus brevis tendon

Explanation: Squeezing the calf normally causes plantarflexion; absence indicates Achilles tendon rupture. Thompson test is thus specific for calcaneal tendon discontinuity, often from sudden dorsiflexion injury. Correct answer: Calcaneal (Achilles) tendon.

4) Which artery mainly supplies the triceps surae muscles?

a) Anterior tibial artery

b) Posterior tibial artery and its branches (peroneal included)

c) Dorsalis pedis artery

d) Femoral artery only

Explanation: The posterior tibial artery and contributions from the peroneal (fibular) artery supply the posterior compartment including triceps surae. Anterior tibial and dorsalis pedis supply anterior structures. Correct answer: Posterior tibial artery and branches. Important in ischemic leg evaluation.

5) Gastrocnemius contributes more to plantarflexion when the knee is:

a) Flexed

b) Extended

c) Neutral – unaffected by knee position

d) Internally rotated

Explanation: Gastrocnemius crosses the knee; it generates more plantarflexion when the knee is extended, as knee flexion slackens it. Soleus (monoarticular) acts regardless of knee position. Correct answer: Extended. Clinical tests consider knee position when assessing calf strength.

6) A positive calf squeeze with no plantarflexion indicates lesion of:

a) Posterior tibial nerve distal to gastrocnemius

b) Achilles tendon rupture

c) Tibialis anterior nerve injury

d) Peroneal nerve palsy

Explanation: The Thompson (calf squeeze) test shows absent plantarflexion in Achilles tendon rupture, not in isolated nerve palsy. Tendon discontinuity prevents force transmission despite intact muscle. Correct answer: Achilles tendon rupture. Prompt management needed to restore push-off.

7) Plantaris muscle, when present, lies between which two structures related to triceps surae?

a) Tibialis anterior and EHL

b) Gastrocnemius and soleus, with a long tendon medial to Achilles

c) Peroneus longus and brevis

d) Flexor hallucis longus and tibialis posterior

Explanation: Plantaris is a small accessory muscle with a long slender tendon that runs between gastrocnemius and soleus and often parallels the Achilles tendon medially. It is sometimes used as a tendon graft. Correct answer: Gastrocnemius and soleus region.

8) Rupture of the Achilles tendon most commonly results in loss of which gait phase action?

a) Heel strike

b) Toe-off/pushoff (plantarflexion phase)

c) Mid-stance stability only

d) Swing phase clearance

Explanation: Achilles rupture prevents effective plantarflexion needed for toe-off/pushoff, leading to impaired propulsion and altered gait. Patients have weak push-off and may show a palpable gap. Correct answer: Toe-off/pushoff. Surgical repair often restores function.

9) Which clinical condition involves pain and tightness of triceps surae with increased compartment pressure?

a) Plantar fasciitis

b) Posterior compartment syndrome of leg

c) Lateral ankle sprain

d) Deep vein thrombosis only

Explanation: Exertional or acute posterior compartment syndrome involves the deep posterior compartment including triceps surae, causing pain, tense swelling, and neurovascular compromise. Urgent fasciotomy is required. Correct answer: Posterior compartment syndrome (affecting calf muscles).

10) Sural nerve sensory distribution relates closely to triceps surae because it supplies:

a) Medial plantar surface of foot

b) Lateral aspect of foot and posterior calf skin overlying gastrocnemius

d) Plantar aspect of toes 2–4

Explanation: The sural nerve provides cutaneous innervation to the posterior calf and lateral foot, areas overlying the gastrocnemius and Achilles tendon. Injury causes sensory loss here and may accompany procedures on the calf. Correct answer: Lateral foot and posterior calf skin.

Keyword Definitions

• Interosseous membrane – Fibrous sheet between radius and ulna, provides attachment for muscles and transmits forces.

• Anterior interosseous artery – Branch of common interosseous artery running on anterior surface of interosseous membrane supplying deep forearm muscles.

• Posterior interosseous artery – Branch that reaches the posterior compartment, often passes through/perforates the interosseous membrane to supply extensors.

• Common interosseous artery – Short trunk from ulnar artery dividing into anterior and posterior interosseous arteries.

• Interosseous space – The gap between radius and ulna occupied by membrane and vessels; communicates between compartments.

• Posterior interosseous nerve – Deep branch of radial nerve running in posterior compartment with posterior interosseous vessels.

• Perforating branches – Small vessels that traverse the interosseous membrane to connect anterior and posterior circulations.

• Clinical relevance – Knowledge is vital in forearm fractures and surgical approaches to avoid vascular injury.

• Supination/pronation force transmission – Interosseous membrane transmits axial loads from radius to ulna during weight-bearing.

• Surgical landmark – Interosseous membrane used as reference during forearm reconstructive procedures.

Chapter: Anatomy / Upper Limb

Topic: Forearm Vessels and Membranes

Subtopic: Interosseous Membrane and its Perforators

Lead Question – 2013

Interosseous membrane of forearm is pierced by?

a) Brachial artery

b) Anterior interosseous artery

c) Posterior interosseous artery

d) Ulnar recurrent artery

Explanation: The posterior interosseous artery typically pierces the interosseous membrane to reach the posterior compartment, accompanying the posterior interosseous nerve. The anterior interosseous artery runs on the anterior surface and sends perforators. Correct answer: Posterior interosseous artery. Clinically important in posterior compartment surgeries and fractures.

Guessed Questions for NEET PG

1) The anterior interosseous artery is a branch of:

a) Radial artery

b) Ulnar artery (via common interosseous)

c) Brachial artery directly

d) Posterior interosseous artery

Explanation: The anterior interosseous artery arises from the common interosseous branch of the ulnar artery and runs on the anterior surface of the interosseous membrane. Correct answer: Ulnar artery (via common interosseous). Clinical: AIN and artery are vulnerable in proximal forearm trauma.

2) Which nerve accompanies the posterior interosseous artery in the posterior compartment?

a) Superficial radial nerve

b) Posterior interosseous nerve (deep branch of radial)

c) Median nerve

d) Ulnar nerve

Explanation: The posterior interosseous nerve (deep branch of radial nerve) accompanies the posterior interosseous artery in the posterior compartment to supply extensor muscles. Correct answer: Posterior interosseous nerve. Clinical: Injury causes finger extension weakness without sensory loss.

3) Perforating branches of the interosseous arteries allow communication between:

a) Radial and ulnar arteries only

b) Anterior and posterior compartments of forearm

c) Superficial and deep palmar arches

d) Brachial and radial arteries

Explanation: Perforators through the interosseous membrane connect anterior and posterior interosseous arteries, providing collateral circulation between forearm compartments. Correct answer: Anterior and posterior compartments. Clinical: Important when primary vessels are injured.

4) Injury to posterior interosseous artery in proximal forearm most likely causes:

a) Pure sensory loss in hand

b) Ischemia of posterior compartment muscles

c) Loss of pronation only

d) Thumb adduction loss

Explanation: Damage to posterior interosseous artery reduces blood supply to posterior (extensor) compartment leading to ischemic pain and weakness. Correct answer: Ischemia of posterior compartment muscles. Clinical: May accompany fractures or surgical insults.

5) The common interosseous artery usually arises from:

a) Radial artery

b) Ulnar artery

c) Brachial artery at cubital fossa

d) Profunda brachii artery

Explanation: The common interosseous artery branches from the ulnar artery shortly after the ulnar origin, then divides into anterior and posterior interosseous arteries. Correct answer: Ulnar artery. Clinical: Variant anatomy can affect flap planning.

6) Which structure runs along the anterior surface of the interosseous membrane?

a) Posterior interosseous artery

b) Anterior interosseous artery and nerve

c) Superficial radial nerve

d) Ulnar nerve

Explanation: The anterior interosseous artery and anterior interosseous branch of median nerve run on the anterior surface of the interosseous membrane supplying deep flexors. Correct answer: Anterior interosseous artery and nerve. Clinical: AIN palsy causes pure motor deficits.

7) The posterior interosseous artery usually reaches the posterior compartment via a gap near which landmark?

a) Lister’s tubercle

b) Proximal border of interosseous membrane near supinator

c) Ulnar styloid process

d) Pisiform bone

Explanation: The posterior interosseous artery commonly passes to the posterior compartment near the proximal border of the interosseous membrane in the region of the supinator. Correct answer: Proximal border of interosseous membrane near supinator. Clinical: Supinator syndrome may compromise vessels and nerve.

8) In a Galeazzi fracture (distal radius with DRUJ disruption), which artery's flow might be compromised affecting interosseous communication?

a) Brachial artery

b) Anterior interosseous artery

c) Posterior tibial artery

d) Median artery

Explanation: A distal radius fracture can disturb branches including anterior interosseous artery or its perforators, impairing collateral flow between compartments. Correct answer: Anterior interosseous artery. Clinical: Assess distal perfusion and nerve function in such injuries.

9) The anterior interosseous artery supplies all EXCEPT:

a) Flexor pollicis longus

b) Pronator quadratus

c) Lateral part of flexor digitorum profundus

d) Extensor digitorum communis

Explanation: The AIN supplies FPL, pronator quadratus, and lateral FDP; it does not supply extensor digitorum communis (posterior compartment). Correct answer: Extensor digitorum communis. Clinical: AIN lesions cause weak thumb and index flexion.

10) Surgical exposure of the posterior forearm should avoid injury to which vessel that pierces the interosseous membrane?

a) Radial artery

b) Posterior interosseous artery

c) Ulnar artery

d) Cephalic vein

Explanation: The posterior interosseous artery pierces the interosseous membrane to reach the posterior compartment and must be preserved during surgical approaches to avoid ischemia of extensor muscles. Correct answer: Posterior interosseous artery. Careful dissection around supinator is required.

Keyword Definitions

• Extensor compartments – Six fibro-osseous dorsal compartments on wrist that guide extensor tendons beneath extensor retinaculum.

• Extensor pollicis longus (EPL) – Tendon that extends the thumb interphalangeal joint; runs in 3rd compartment around Lister’s tubercle.

• Extensor carpi radialis longus (ECRL) – Wrist extensor and radial abductor; runs in 2nd compartment (partly).

• Extensor carpi radialis brevis (ECRB) – Wrist extensor in 2nd compartment; often involved in lateral epicondylitis.

• Extensor pollicis brevis (EPB) – Short thumb extensor in 1st compartment with APL.

• Lister’s tubercle – Dorsal tubercle of radius that acts as a pulley for EPL tendon (3rd compartment).

• De Quervain’s tenosynovitis – Stenosing tenosynovitis of 1st dorsal compartment (APL, EPB).

• Intersection syndrome – Overuse tenosynovitis where 1st compartment tendons cross 2nd compartment tendons.

• Extensor retinaculum – Fibrous band holding extensor tendons in compartments at wrist.

• Clinical importance – Identifying compartment involved helps diagnose dorsal wrist pain and plan surgical release.

Chapter: Anatomy / Upper Limb

Topic: Wrist and Hand

Subtopic: Dorsal Extensor Compartments of Wrist

Lead Question – 2013

3rd extensor compartment of wrist contains tendon of ?

a) ECRL

b) ECRB

c) EPL

d) EPB

Explanation: The third dorsal compartment contains the extensor pollicis longus (EPL) tendon as it uses Lister’s tubercle as a pulley, redirecting its line of pull to extend the thumb. Correct answer: EPL. Clinically, EPL rupture may follow distal radius fractures and presents as loss of thumb IP extension.

Guessed Questions for NEET PG

1) First dorsal compartment contains tendons of:

a) APL & EPB

b) EPL only

c) ECRL & ECRB

d) Extensor digitorum

Explanation: The first dorsal compartment contains abductor pollicis longus (APL) and extensor pollicis brevis (EPB). Stenosis here causes de Quervain’s tenosynovitis with radial wrist pain. Correct answer: APL & EPB. Treatment includes splinting or compartmental release.

2) Second dorsal compartment contains which tendons?

a) ECRL & ECRB

b) EPL only

c) APL & EPB

d) Extensor digiti minimi

Explanation: The second compartment contains extensor carpi radialis longus and brevis (ECRL, ECRB). These tendons glide under the retinaculum and are implicated in intersection syndrome when irritated by crossing first-compartment tendons. Correct answer: ECRL & ECRB.

3) Lister’s tubercle is clinically significant because it:

a) Is attachment for ECU

b) Acts as pulley for EPL tendon

c) Houses radial artery

d) Is origin of APL

Explanation: Lister’s tubercle on the distal radius acts as a dorsal pulley for the EPL tendon, changing its direction toward the thumb. After distal radius fractures, EPL attrition or rupture can occur here. Correct answer: Acts as pulley for EPL tendon.

4) De Quervain’s tenosynovitis typically presents with pain at:

a) Ulnar styloid

b) Radial styloid / lateral wrist

c) Dorsal midcarpal region

d) Pisiform area

Explanation: De Quervain’s affects APL and EPB in the first dorsal compartment causing pain and tenderness at the radial styloid. Finkelstein’s test reproduces pain. Correct answer: Radial styloid / lateral wrist. Management includes splinting and steroid injection.

5) Extensor digitorum communis (EDC) tendons lie in which compartment primarily?

a) Third

b) Fourth

c) Fifth

d) Sixth

Explanation: The fourth dorsal compartment houses the extensor digitorum communis (EDC) tendons and extensor indicis. Correct answer: Fourth. Clinical: Extensor tendon injuries in this compartment affect finger extension and may require repair or tenodesis.

6) Extensor digiti minimi runs in which compartment?

a) First

b) Second

c) Fifth

d) Sixth

Explanation: The fifth dorsal compartment contains the extensor digiti minimi tendon (to little finger). Tenosynovitis here causes localized dorsal ulnar wrist pain. Correct answer: Fifth compartment. Surgical release may be needed for refractory cases.

7) Extensor carpi ulnaris (ECU) tendon lies in which compartment?

a) Third

b) Fourth

c) Fifth

d) Sixth

Explanation: The sixth dorsal compartment contains the extensor carpi ulnaris (ECU) tendon running along the ulnar side. ECU subluxation or tendinopathy causes ulnar-sided wrist pain, especially in racket sports. Correct answer: Sixth compartment.

8) Intersection syndrome involves friction where first compartment tendons cross which compartment?

a) Second compartment tendons

b) Third compartment tendons

c) Fourth compartment tendons

d) Fifth compartment tendons

Explanation: Intersection syndrome results from friction where APL/EPB (1st compartment) cross over ECRL/ECRB (2nd compartment) about 4–8 cm proximal to wrist, producing forearm pain and crepitus. Correct answer: Second compartment tendons.

9) Rupture of EPL tendon is most commonly associated with which injury?

a) Distal radius fracture

b) Scaphoid fracture

c) Hamate fracture

d) Colles’ dislocation only

Explanation: EPL rupture classically follows distal radius fractures due to attrition at Lister’s tubercle or ischemia of the tendon sheath. Patients lose active IP extension of thumb. Correct answer: Distal radius fracture. Surgical tendon transfer may be required.

10) A swollen dorsal wrist with pain on thumb extension and positive Finkelstein’s test indicates involvement of which compartment?

a) First compartment

b) Third compartment

c) Fourth compartment

d) Sixth compartment

Explanation: Positive Finkelstein’s test with radial styloid tenderness indicates first compartment stenosing tenosynovitis (APL & EPB) — de Quervain’s disease. Correct answer: First compartment. Conservative treatment includes rest, splinting, and steroid injection.

Keyword Definitions

• Supination – Outward rotation of forearm turning palm upward.

• Pronation – Inward rotation of forearm turning palm downward.

• Biceps brachii – Flexor of elbow and chief supinator when forearm flexed.

• Supinator muscle – Assists in supination, especially when elbow extended.

• Brachioradialis – Flexes elbow, acts in mid-prone position, not supination.

• FDS (Flexor digitorum superficialis) – Flexes middle phalanges, unrelated to supination.

• Anconeus – Assists in elbow extension, stabilizes joint, not in supination.

• Musculocutaneous nerve – Innervates biceps brachii.

• Radial nerve – Innervates supinator and brachioradialis.

• Clinical test – Turning a screwdriver tests supination and biceps activity.

• Spiral groove – Radial nerve and profunda brachii pass here, relevant for supinator function.

Chapter: Anatomy / Upper Limb

Topic: Muscles of Forearm and Arm

Subtopic: Supinators of Forearm

Lead Question – 2013

Muscle causing supination of forearm?

a) Biceps brachii

b) Brachioradialis

c) FDS

d) Anconeus

Explanation: Supination is mainly caused by biceps brachii when the elbow is flexed and by supinator when the elbow is extended. Other listed muscles are not supinators. Correct answer: (a) Biceps brachii. Clinical: Weak supination occurs in musculocutaneous nerve or radial nerve injury.

Guessed Questions for NEET PG

1) Supination in extended elbow is mainly by?

a) Supinator

b) Biceps brachii

c) Pronator teres

d) Anconeus

Explanation: Supinator acts strongly when elbow is extended, while biceps dominates in flexion. Correct answer: Supinator. Clinical: Radial nerve injury weakens supination.

2) Which nerve supplies the supinator muscle?

a) Median

b) Radial (deep branch)

c) Musculocutaneous

d) Ulnar

Explanation: Supinator is supplied by deep branch of radial nerve. Correct answer: Radial nerve (deep branch). Clinical: Compression in supinator leads to posterior interosseous nerve syndrome.

3) Turning a screwdriver involves mainly?

a) Pronator quadratus

b) Biceps brachii

c) Anconeus

d) Flexor carpi radialis

Explanation: Biceps brachii provides strong supination, especially in flexed forearm. Correct answer: Biceps brachii. Clinical: Fatigue in this muscle seen in repetitive screw turning.

4) A patient with musculocutaneous nerve injury will have weakness in?

a) Supination with flexed elbow

b) Supination with extended elbow

c) Pronation

d) Wrist extension

Explanation: Musculocutaneous nerve supplies biceps brachii, the chief supinator in flexion. Correct answer: Supination with flexed elbow. Clinical: Weakness plus sensory loss lateral forearm.

5) Which movement is preserved in posterior interosseous nerve injury?

a) Finger extension

b) Supination with flexed elbow

c) Wrist extension

d) Thumb abduction

Explanation: Biceps brachii (musculocutaneous) compensates supination in flexion. Correct answer: Supination with flexed elbow. Clinical: Posterior interosseous palsy spares biceps function.

6) Which muscle is a synergist in both pronation and supination, bringing forearm to mid-prone?

a) Supinator

b) Biceps brachii

c) Brachioradialis

d) Pronator teres

Explanation: Brachioradialis brings forearm into mid-prone from either side. Correct answer: Brachioradialis. Clinical: Preserved action in radial nerve palsy proximal to its branch.

7) Supination test in clinical examination mainly evaluates?

a) Median nerve

b) Musculocutaneous nerve

c) Ulnar nerve

d) Axillary nerve

Explanation: Supination in flexion depends on biceps brachii, innervated by musculocutaneous nerve. Correct answer: Musculocutaneous nerve. Clinical: Used to assess injury after trauma.

8) Which muscle is NOT involved in forearm supination?

a) Supinator

b) Biceps brachii

c) Brachioradialis

d) FDS

Explanation: FDS is a finger flexor, has no role in forearm rotation. Correct answer: FDS. Clinical: Misconception often tested in exams.

9) In radial head dislocation (nursemaid’s elbow), which movement is restricted?

a) Pronation

b) Supination

c) Flexion

d) Extension

Explanation: Dislocated radial head impairs supination since supinator attaches here. Correct answer: Supination. Clinical: Common in children lifted by hand.

10) In fracture of surgical neck of humerus sparing biceps, supination is?

a) Lost completely

b) Weak but present

c) Normal

d) Exaggerated

Explanation: Biceps brachii (musculocutaneous) remains intact; supination is preserved. Correct answer: Normal. Clinical: Differentiates between radial and musculocutaneous lesions.

Keyword Definitions

• Midpalmar space – Deep fascial space of hand located beneath central compartment, communicates with forearm via carpal tunnel.

• Lumbricals – Four small intrinsic hand muscles arising from flexor digitorum profundus tendons.

• FDP – Flexor digitorum profundus, flexes distal interphalangeal joints.

• Thenar space – Fascial space near thumb, separated from midpalmar space by septum.

• Hand compartments – Thenar, hypothenar, adductor, central, interosseous compartments.

• Clinical correlation – Midpalmar abscess can spread to forearm through carpal tunnel.

• Carpal tunnel – Passage for FDP, FDS tendons, FPL tendon, and median nerve.

• Infection spread – From finger pulp to midpalmar space via lumbrical canals.

• Surgical drainage – Important in treating deep palmar space infections.

• Lumbrical canal – Interval through which lumbrical muscles enter palm from FDP.

• Interossei – Intrinsic hand muscles not part of midpalmar space content.

Chapter: Anatomy / Upper Limb

Topic: Hand

Subtopic: Midpalmar Space

Lead Question – 2013

Contents of midpalmar space are all except

a) 2nd lumbrical

b) FDP of 3rd finger

c) 1st lumbrical

d) FDP of 4th finger

Explanation: Midpalmar space contains medial three lumbricals and flexor digitorum profundus tendons of middle, ring, and little fingers. The 1st lumbrical belongs to thenar space, not midpalmar. Correct answer: (c) 1st lumbrical. Clinical: Midpalmar abscess can cause swelling in central palm and requires careful surgical drainage.

Guessed Questions for NEET PG

1) Which lumbrical muscle lies in thenar space?

a) 1st lumbrical

b) 2nd lumbrical

c) 3rd lumbrical

d) 4th lumbrical

Explanation: The 1st lumbrical lies in thenar space along with FPL tendon. Others lie in midpalmar space. Correct answer: 1st lumbrical. Clinical: Swelling of thenar space may compromise thumb movements.

2) Infection from the index finger pulp may spread to?

a) Thenar space

b) Midpalmar space

c) Hypothenar space

d) Dorsum of hand

Explanation: Lumbrical canal of index finger connects pulp with thenar space. Correct answer: Thenar space. Clinical: Early drainage is essential to preserve thumb function.

3) Which tendon passes through carpal tunnel and continues into midpalmar space?

a) FPL

b) FDP

c) Extensor digitorum

d) Palmaris longus

Explanation: Flexor digitorum profundus tendons pass through carpal tunnel and form part of midpalmar space contents. Correct answer: FDP. Clinical: Infections may spread from palm to forearm via carpal tunnel.

4) Midpalmar space infection presents with swelling in which region?

a) Thenar eminence

b) Hypothenar eminence

c) Central palm

d) Dorsal web space

Explanation: Midpalmar space infections typically cause fullness in central palm. Correct answer: Central palm. Clinical: Deep abscess requires surgical drainage through palmar incision.

5) Which of the following is not a boundary of midpalmar space?

a) Palmar aponeurosis

b) Metacarpals of index finger

c) Interossei muscles

d) Flexor pollicis longus

Explanation: FPL belongs to thenar space, not boundary of midpalmar space. Correct answer: FPL. Clinical: Differentiating compartments is crucial in infection management.

6) Which lumbricals are supplied by ulnar nerve?

a) 1st and 2nd

b) 3rd and 4th

c) All four

d) None

Explanation: The 3rd and 4th lumbricals are supplied by the deep branch of ulnar nerve. Correct answer: 3rd and 4th. Clinical: Ulnar nerve injury affects fine grip due to lumbrical paralysis.

7) Patient with midpalmar space infection is unable to flex distal phalanx of ring finger. Which tendon is affected?

a) FDS

b) FDP

c) FPL

d) Extensor indicis

Explanation: FDP of ring finger passes through midpalmar space, infection can impair its function. Correct answer: FDP. Clinical: This indicates deep involvement requiring urgent drainage.

8) Which muscle group borders the midpalmar space dorsally?

a) Palmaris brevis

b) Interossei

c) Thenar muscles

d) Hypothenar muscles

Explanation: Interossei muscles form dorsal boundary of midpalmar space. Correct answer: Interossei. Clinical: Infection here can spread to intermetacarpal spaces.

9) Midpalmar space communicates with forearm via?

a) Anatomical snuffbox

b) Carpal tunnel

c) Guyon’s canal

d) Radial bursa

Explanation: Midpalmar space communicates proximally through carpal tunnel with forearm. Correct answer: Carpal tunnel. Clinical: Explains spread of deep hand infections to forearm flexor sheath.

10) Which space is affected in a patient unable to oppose thumb with swelling near 1st web space?

a) Midpalmar space

b) Thenar space

c) Hypothenar space

d) Dorsal space

Explanation: Thenar space infection affects thumb opposition and causes swelling near first web space. Correct answer: Thenar space. Clinical: Misdiagnosis may lead to permanent disability of thumb.

Keyword Definitions

• Superficial anterior compartment of forearm – Contains five muscles: pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis.

• FDS – Flexor digitorum superficialis, a superficial flexor of fingers.

• FCR – Flexor carpi radialis, wrist flexor and abductor.

• Palmaris longus – Weak wrist flexor, absent in 10-15% individuals.

• FPL – Flexor pollicis longus, belongs to deep compartment, flexes thumb.

• Median nerve – Supplies most superficial anterior forearm muscles.

• Ulnar nerve – Supplies flexor carpi ulnaris and medial half of FDP.

• Brachial artery – Main arterial supply of forearm, divides into radial and ulnar.

• Clinical correlation – Superficial muscles are commonly involved in tendinitis and occupational overuse syndromes.

• Compartment syndrome – Increased pressure in forearm compartments can damage muscles and nerves.

• Pronator teres syndrome – Median nerve entrapment by pronator teres in superficial compartment.

Chapter: Anatomy / Upper Limb

Topic: Forearm Muscles

Subtopic: Superficial anterior compartment of forearm

Lead Question – 2013

Which of the following is not the muscle of superficial anterior compartment of forearm?

a) FDS

b) FPL

c) FCR

d) Palmaris longus

Explanation: The superficial anterior compartment includes pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and flexor digitorum superficialis. Flexor pollicis longus is a deep compartment muscle. Correct answer: (b) FPL. Clinical: FPL is important in thumb flexion and tested in anterior interosseous nerve palsy.

Guessed Questions for NEET PG

1) Which of the following is a superficial flexor of forearm?

a) Pronator teres

b) Flexor pollicis longus

c) Flexor digitorum profundus

d) Supinator

Explanation: Pronator teres belongs to superficial anterior compartment. FPL and FDP are deep flexors, supinator belongs to posterior compartment. Correct answer: Pronator teres. Clinical: Median nerve may be compressed between its two heads.

2) Which superficial anterior forearm muscle is most frequently absent in population?

a) FCR

b) FCU

c) Palmaris longus

d) Pronator teres

Explanation: Palmaris longus is absent in about 10–15% of individuals. Correct answer: Palmaris longus. Clinical: Its tendon is used in reconstructive tendon graft surgeries without functional deficit.

3) Which muscle is supplied by ulnar nerve among superficial flexors?

a) FCR

b) FCU

c) Palmaris longus

d) Pronator teres

Explanation: Flexor carpi ulnaris is the only superficial flexor supplied by the ulnar nerve. Others are supplied by median nerve. Correct answer: FCU. Clinical: Weak wrist flexion and ulnar deviation occur in lesions.

4) A patient unable to flex PIP joints of fingers likely has paralysis of?

a) FDP

b) FDS

c) FPL

d) FCU

Explanation: Flexor digitorum superficialis flexes proximal interphalangeal joints. Correct answer: FDS. Clinical: Median nerve lesions at elbow impair this function.

5) Which muscle originates from common flexor origin on medial epicondyle?

a) Palmaris longus

b) Pronator teres

c) FCR

d) All of the above

Explanation: All superficial flexors except FDS deep head arise from medial epicondyle via common flexor origin. Correct answer: All of the above. Clinical: Overuse may cause medial epicondylitis (golfer’s elbow).

6) Flexor pollicis longus is supplied by?

a) Median nerve (anterior interosseous branch)

b) Ulnar nerve

c) Radial nerve

d) Posterior interosseous nerve

Explanation: FPL is innervated by anterior interosseous branch of median nerve. Correct answer: Median nerve (AIN). Clinical: AIN palsy causes inability to make “OK” sign due to FPL weakness.

7) Which superficial flexor muscle is involved in carpal tunnel syndrome symptoms due to tendinopathy?

a) FDS

b) FCR

c) FCU

d) Pronator teres

Explanation: Flexor digitorum superficialis tendons pass through carpal tunnel and may contribute to compression. Correct answer: FDS. Clinical: CTS presents with numbness, tingling in lateral fingers.

8) Median nerve lies deep to which superficial muscle at wrist?

a) FCU

b) FCR

c) Palmaris longus

d) Pronator teres

Explanation: Palmaris longus tendon lies superficial to median nerve at wrist. Correct answer: Palmaris longus. Clinical: Median nerve blocks may be guided by this relation.

9) Which superficial forearm muscle flexes and abducts the wrist?

a) FCR

b) FCU

c) Palmaris longus

d) FDS

Explanation: Flexor carpi radialis flexes wrist and abducts it towards radial side. Correct answer: FCR. Clinical: FCR tendon is palpable in radial wrist and used for arterial cannulation landmark.

10) In anterior compartment syndrome, which superficial muscle is most vulnerable due to location?

a) Pronator teres

b) FCR

c) FCU

d) FDS

Explanation: Flexor digitorum superficialis, being central and bulky, is commonly affected in increased compartment pressure. Correct answer: FDS. Clinical: Early decompression prevents ischemic contracture (Volkmann’s).

Keyword Definitions

• Dual nerve supply – Muscle receiving motor innervation from two different nerves.

• Subscapularis – Supplied by upper and lower subscapular nerves.

• Pectoralis major – Supplied by medial and lateral pectoral nerves.

• Pronator teres – Supplied by median nerve only.

• Flexor digitorum profundus – Medial half by ulnar nerve, lateral half by anterior interosseous branch of median nerve.

• Brachial plexus – Network of nerves supplying upper limb, roots C5–T1.

• Median nerve – Formed by medial and lateral cords, supplies most forearm flexors.

• Ulnar nerve – Arises from medial cord, supplies intrinsic hand muscles and medial FDP.

• Subscapular nerves – Branches of posterior cord, innervate subscapularis.

• Clinical correlation – Knowledge of dual supply important in nerve lesions and recovery.

• Muscle palsy – Weakness pattern helps localize lesion to specific nerve or part of plexus.

Chapter: Anatomy / Upper Limb

Topic: Brachial Plexus and Muscle Innervation

Subtopic: Dual nerve supply of upper limb muscles

Lead Question – 2013

All of the following muscles have dual nerve supply except?

a) Subscapularis

b) Pectoralis major

c) Pronator teres

d) Flexor digitorum profundus

Explanation: Subscapularis has dual supply (upper and lower subscapular nerves). Pectoralis major has dual supply (medial and lateral pectoral nerves). FDP has dual supply (median and ulnar nerves). Pronator teres has single supply (median nerve). Correct answer: (c) Pronator teres. Clinical: Isolated median injury can paralyze pronator teres completely.

Guessed Questions for NEET PG

1) Which muscle among the following is supplied by both ulnar and median nerves?

a) Flexor pollicis longus

b) Flexor carpi radialis

c) Flexor digitorum profundus

d) Pronator quadratus

Explanation: Flexor digitorum profundus has dual supply – medial half by ulnar, lateral half by anterior interosseous (median). Correct answer: FDP. Clinical: Explains partial preservation in isolated lesions.

2) Subscapularis is supplied by?

a) Upper and lower subscapular nerves

b) Thoracodorsal nerve

c) Lateral pectoral nerve

d) Axillary nerve

Explanation: Subscapularis is innervated by both upper and lower subscapular nerves from posterior cord. Correct answer: Upper and lower subscapular nerves. Clinical: Injury leads to weak internal rotation.

3) Which muscle receives innervation from both medial and lateral pectoral nerves?

a) Pectoralis major

b) Pectoralis minor

c) Subclavius

d) Serratus anterior

Explanation: Pectoralis major is supplied by medial and lateral pectoral nerves. Correct answer: Pectoralis major. Clinical: Paralysis leads to weak adduction and internal rotation.

4) A patient with ulnar nerve lesion at wrist retains partial flexion of DIP of ring finger due to?

a) Median nerve supply

b) Radial nerve supply

c) Musculocutaneous nerve supply

d) Axillary nerve supply

Explanation: Lateral half of FDP (index and middle fingers) supplied by median, medial half (ring and little fingers) by ulnar. Correct answer: Median nerve supply. Clinical: Explains incomplete loss in ulnar palsy.

5) Which of the following has single nerve supply?

a) FDP

b) Pectoralis major

c) Pronator teres

d) Subscapularis

Explanation: Pronator teres is solely supplied by median nerve. Others have dual innervation. Correct answer: Pronator teres. Clinical: Useful in lesion localization.

6) Which nerve supplies medial half of flexor digitorum profundus?

a) Ulnar

b) Median

c) Radial

d) Musculocutaneous

Explanation: Medial half (ring and little fingers) of FDP is innervated by ulnar nerve. Correct answer: Ulnar nerve. Clinical: Explains weakness of DIP flexion in ulnar palsy.

7) Damage to lateral pectoral nerve causes weakness in?

a) Shoulder abduction

b) Arm adduction

c) Elbow flexion

d) Wrist extension

Explanation: Lateral pectoral nerve innervates pectoralis major, main action is adduction and internal rotation of arm. Correct answer: Arm adduction. Clinical: Loss of powerful adduction in lesion.

8) A patient with lesion of posterior cord affecting both upper and lower subscapular nerves shows weakness in?

a) Internal rotation

b) External rotation

c) Abduction

d) Supination

Explanation: Subscapularis performs internal rotation of humerus, supplied by both upper and lower subscapular nerves. Correct answer: Internal rotation. Clinical: Shoulder stability is also reduced.

9) Median nerve injury at elbow spares which of the following?

a) Pronator teres

b) Flexor digitorum profundus (medial half)

c) Flexor digitorum superficialis

d) Flexor pollicis longus

Explanation: Medial half of FDP is supplied by ulnar nerve, hence spared in median nerve injury at elbow. Correct answer: FDP (medial half). Clinical: Explains partial preservation of finger flexion.

10) Which of the following combinations represent dual innervation correctly?

a) FDP – Median & Ulnar

b) Pectoralis major – Medial & Lateral pectoral

c) Subscapularis – Upper & Lower subscapular

d) All of the above

Explanation: All mentioned muscles are examples of dual innervation. Correct answer: All of the above. Clinical: Important for understanding muscle function in partial nerve injuries.

Keyword Definitions

• Pectoral region – The area on the anterior chest wall related to pectoral muscles.

• Pectoralis major – Large superficial chest muscle aiding arm adduction and medial rotation.

• Pectoralis minor – Lies deep to pectoralis major, attaches coracoid process to ribs.

• Subclavius – Small muscle beneath clavicle, stabilizes clavicle.

• Infraspinatus – Rotator cuff muscle of scapula, not part of pectoral region.

• Axilla – Space beneath pectoral region transmitting vessels and nerves.

• Thoracoacromial artery – Main arterial supply of pectoral region.

• Medial and lateral pectoral nerves – Innervation of pectoralis muscles.

• Clinical correlation – Trauma or surgery of chest may injure pectoral nerves.

• Rotator cuff – Group of muscles stabilizing shoulder joint, includes infraspinatus.

• Breast surgery relevance – Pectoralis muscles form bed of breast and are key in mastectomy.

Chapter: Anatomy / Upper Limb

Topic: Pectoral Region and Axilla

Subtopic: Muscles of pectoral region

Lead Question – 2013

Which of the following muscle is not in the pectoral region?

a) Pectoralis major

b) Infraspinatus

c) Pectoralis minor

d) Subclavius

Explanation: The pectoral region consists of pectoralis major, pectoralis minor, and subclavius. Infraspinatus is located on posterior aspect of scapula, part of rotator cuff, not pectoral region. Correct answer: (b) Infraspinatus. Clinical: Important to distinguish anterior chest muscles from posterior scapular muscles.

Guessed Questions for NEET PG

1) Which nerve supplies pectoralis major?

a) Thoracodorsal nerve

b) Medial and lateral pectoral nerves

c) Axillary nerve

d) Suprascapular nerve

Explanation: Pectoralis major is supplied by both medial and lateral pectoral nerves. Correct answer: Medial and lateral pectoral nerves. Clinical: Nerve injury may weaken adduction and medial rotation of arm.

2) Which structure lies deep to pectoralis minor?

a) Brachial plexus cords

b) Cephalic vein

c) Basilic vein

d) Ulnar nerve

Explanation: Pectoralis minor is a landmark for cords of brachial plexus and axillary vessels. Correct answer: Brachial plexus cords. Clinical: Used as a guide in axillary dissections.

3) Subclavius muscle function is?

a) Elevates scapula

b) Depresses clavicle

c) Flexes humerus

d) Extends arm

Explanation: Subclavius depresses and stabilizes the clavicle during shoulder movements. Correct answer: Depresses clavicle. Clinical: Provides protection to subclavian vessels during clavicular fracture.

4) Which artery mainly supplies pectoralis major?

a) Subclavian artery

b) Thoracoacromial artery

c) Radial artery

d) Subscapular artery

Explanation: The thoracoacromial artery, a branch of axillary artery, supplies pectoralis major. Correct answer: Thoracoacromial artery. Clinical: Important during reconstructive flap surgeries.

5) A breast carcinoma infiltrating deep fascia can involve which muscle first?

a) Serratus anterior

b) Pectoralis major

c) Infraspinatus

d) Latissimus dorsi

Explanation: Pectoralis major forms the bed of breast, hence infiltrated in advanced carcinoma. Correct answer: Pectoralis major. Clinical: Explains fixation of breast mass to chest wall.

6) Which muscle is part of rotator cuff but not pectoral region?

a) Subscapularis

b) Infraspinatus

c) Supraspinatus

d) Teres minor

Explanation: Infraspinatus is part of rotator cuff, not pectoral region. Correct answer: Infraspinatus. Clinical: Weakness causes loss of external rotation at shoulder.

7) Injury to medial pectoral nerve causes weakness of?

a) Deltoid

b) Pectoralis minor

c) Latissimus dorsi

d) Teres major

Explanation: Medial pectoral nerve supplies pectoralis minor and part of pectoralis major. Correct answer: Pectoralis minor. Clinical: May weaken scapular protraction.

8) Which lymph nodes lie deep to pectoralis minor?

a) Apical

b) Central

c) Lateral

d) Subscapular

Explanation: Apical group of axillary lymph nodes lie deep to pectoralis minor. Correct answer: Apical. Clinical: Important in breast cancer spread and axillary clearance surgeries.

9) A patient with winging of scapula likely has injury to?

a) Medial pectoral nerve

b) Long thoracic nerve

c) Axillary nerve

d) Suprascapular nerve

Explanation: Winging of scapula occurs due to serratus anterior paralysis from long thoracic nerve injury. Correct answer: Long thoracic nerve. Clinical: Seen in radical mastectomy complications.

10) Which of the following is not a muscle of anterior axillary fold?

a) Pectoralis major

b) Pectoralis minor

c) Subclavius

d) Latissimus dorsi

Explanation: Anterior axillary fold is formed by lower border of pectoralis major. Latissimus dorsi forms posterior fold. Correct answer: Latissimus dorsi. Clinical: Used in surgical identification of axillary folds.

Keyword Definitions

• Bursa – Fluid-filled sac reducing friction between tendon and bone.

• Synovial sheath – Tubular bursa surrounding a tendon for smooth gliding.

• Radial bursa – Synovial sheath enclosing flexor pollicis longus tendon.

• Ulnar bursa – Common flexor sheath for FDP and FDS tendons.

• Flexor pollicis longus (FPL) – Muscle flexing thumb distal phalanx.

• Flexor digitorum profundus (FDP) – Muscle flexing distal phalanges of fingers.

• Flexor digitorum superficialis (FDS) – Muscle flexing middle phalanges.

• Flexor carpi radialis (FCR) – Wrist flexor inserting into 2nd metacarpal.

• Thenar space – Potential space in palm communicating with radial bursa.

• Midpalmar space – Potential space in palm communicating with ulnar bursa.

• Clinical relevance – Infections of synovial sheaths may spread rapidly to palm and forearm.

Chapter: Anatomy / Upper Limb

Topic: Hand and Forearm Structures

Subtopic: Synovial Sheaths and Bursae of Hand

Lead Question – 2013

Radial bursa is the synovial sheath covering the tendon of ?

a) FDS

b) FDP

c) FPL

d) FCR

Explanation: The radial bursa is the synovial sheath of flexor pollicis longus (FPL) tendon. It extends from wrist into the thumb. Correct answer: FPL. Clinical: infection here (tenosynovitis) may spread into the forearm and cause “horseshoe abscess” by communicating with the ulnar bursa.

Guessed Questions for NEET PG

1) Ulnar bursa covers tendons of:

a) FPL

b) FDP and FDS

c) FCR

d) EPL

Explanation: Ulnar bursa is the common flexor sheath enclosing tendons of FDP and FDS to fingers. Correct answer: FDP and FDS. Clinical: infections here can spread into midpalmar space, causing swelling and impaired finger movements.

2) Horseshoe abscess occurs due to communication between:

a) Radial and ulnar bursa

b) Ulnar bursa and carpal tunnel

c) Radial bursa and midpalmar space

d) Thenar and hypothenar spaces

Explanation: Radial bursa of thumb communicates with ulnar bursa of little finger, producing a characteristic “horseshoe-shaped abscess.” Correct answer: Radial and ulnar bursa. Clinical: requires early drainage to prevent spread to forearm.

3) Infection of thumb flexor tendon sheath may spread into:

a) Thenar space

b) Midpalmar space

c) Parona’s space

d) Dorsum of hand

Explanation: FPL tendon sheath infection spreads through radial bursa into Parona’s space (forearm). Correct answer: Parona’s space. Clinical: severe swelling of forearm seen in advanced tenosynovitis.

4) Which tendon passes separately in its own sheath within carpal tunnel?

a) FPL

b) FDP

c) FDS

d) Palmaris longus

Explanation: FPL passes in its own synovial sheath (radial bursa) through the carpal tunnel. Correct answer: FPL. Clinical: inflammation here may cause isolated thumb pain in carpal tunnel syndrome.

5) Parona’s space is located:

a) Between palmar aponeurosis and flexor tendons

b) Between pronator quadratus and flexor tendons

c) In dorsal hand

d) In thenar eminence

Explanation: Parona’s space is between pronator quadratus and flexor tendons in distal forearm. Correct answer: Between pronator quadratus and flexor tendons. Clinical: serves as pathway for spread of infection from radial or ulnar bursa.

6) Which of the following muscles inserts into the distal phalanx of thumb?

a) FPL

b) FDS

c) FDP

d) EPL

Explanation: Flexor pollicis longus (FPL) inserts into the base of distal phalanx of thumb, flexing IP joint. Correct answer: FPL. Clinical: important in pinch grip strength, loss indicates anterior interosseous nerve palsy.

7) Ulnar bursa commonly extends up to which finger?

a) Index

b) Middle

c) Ring

d) Little

Explanation: The ulnar bursa extends into the little finger flexor sheath. Correct answer: Little finger. Clinical: explains why infections of little finger flexor sheath can spread to common flexor sheath and palm.

8) Which structure is enclosed within both radial bursa and carpal tunnel?

a) FCR

b) FPL

c) EPL

d) Lumbricals

Explanation: FPL tendon passes through carpal tunnel inside its radial bursa sheath. Correct answer: FPL. Clinical: tenosynovitis here may mimic carpal tunnel syndrome with isolated thumb symptoms.

9) A 25-year-old presents with swelling of thumb and little finger tendon sheaths with forearm spread. Most likely condition?

a) Thenar abscess

b) Midpalmar abscess

c) Horseshoe abscess

d) Carpal tunnel syndrome

Explanation: Simultaneous infection of radial and ulnar bursae produces characteristic horseshoe abscess. Correct answer: Horseshoe abscess. Clinical: requires surgical drainage through palmar incisions.

10) Which flexor tendon does not pass through the carpal tunnel?

a) FCR

b) FDP

c) FDS

d) FPL

Explanation: Flexor carpi radialis (FCR) passes in its own canal, not inside carpal tunnel. Correct answer: FCR. Clinical: helps distinguish isolated FCR tenosynovitis from carpal tunnel pathologies.

Keyword Definitions

• Cardiac muscle – Specialized involuntary muscle forming the myocardium; responsible for heart contractions.

• Myocardium – Thick middle layer of heart wall made of cardiac muscle; contracts to pump blood.

• Intercalated discs – Specialized junctions connecting cardiac muscle cells; contain desmosomes and gap junctions.

• Gap junctions – Channels allowing electrical coupling between cardiac myocytes for synchronized contraction.

• Nucleus – Cardiac muscle cells typically have one centrally located nucleus; occasionally two.

• Striations – Alternating light and dark bands in cardiac muscle due to organized sarcomeres.

• Sheet arrangement – Cardiac muscle fibers arranged in branching sheets for efficient contraction.

• Spindle-shaped – Characteristic of smooth muscle, not cardiac muscle.

• Clinical relevance – Dysfunction of cardiac muscle leads to arrhythmias, heart failure, or cardiomyopathies.

• Histology – Cardiac muscle cells are short, branched, striated, with intercalated discs and central nuclei.

Chapter: Histology / Muscular System

Topic: Cardiac Muscle

Subtopic: Structure, Histology, and Clinical Relevance

Lead Question – 2013

True about cardiac muscle is?

a) Spindle shaped

b) Large central nucleus

c) No gap junctions

d) Arranged in sheets

Explanation: Cardiac muscle fibers are arranged in branching sheets, enabling coordinated contractions. Correct answer: Arranged in sheets. They are striated, short, branched, with one central nucleus and intercalated discs containing gap junctions. Spindle-shaped is smooth muscle. Clinically, the sheet arrangement ensures synchronized myocardial contraction and efficient blood pumping.

Guessed Questions for NEET PG

1) Cardiac muscle fibers are:

a) Striated

b) Non-striated

c) Voluntary

d) Spindle-shaped

Explanation: Cardiac muscle is striated due to sarcomere organization. Correct answer: Striated. Clinical: Striations are essential for contraction; histological changes indicate cardiomyopathies.

2) Intercalated discs contain:

a) Desmosomes and gap junctions

b) Tight junctions only

c) Hemidesmosomes only

d) None

Explanation: Intercalated discs connect cardiac myocytes via desmosomes for mechanical strength and gap junctions for electrical coupling. Correct answer: Desmosomes and gap junctions. Clinical: defects cause arrhythmias.

3) Nucleus in cardiac myocytes is typically:

a) Single and central

b) Multiple and peripheral

c) Absent

d) Peripheral only

Explanation: Cardiac myocytes usually have a single centrally located nucleus. Correct answer: Single and central. Clinical: nuclear abnormalities may indicate hypertrophy or cardiomyopathy.

4) Cardiac muscle is controlled by:

a) Autonomic nervous system

b) Somatic nervous system

c) Hormones only

d) Voluntary control

Explanation: Cardiac muscle contracts involuntarily under autonomic nervous system regulation. Correct answer: Autonomic nervous system. Clinical: autonomic dysfunction affects heart rate and rhythm.

5) Branching of cardiac fibers allows:

a) Efficient force distribution

b) Limited contraction

c) No contraction

d) Smooth movement only

Explanation: Branching ensures synchronized contraction and effective pumping. Correct answer: Efficient force distribution. Clinical: branching abnormalities reduce cardiac efficiency.

6) Gap junctions allow:

a) Electrical coupling

b) Structural support only

c) Nutrient diffusion only

d) No function

Explanation: Gap junctions permit ion flow between cardiac cells for coordinated contraction. Correct answer: Electrical coupling. Clinical: defective gap junctions cause arrhythmias.

7) Spindle-shaped cells are characteristic of:

a) Smooth muscle

b) Cardiac muscle

c) Skeletal muscle

d) Connective tissue

Explanation: Spindle-shaped cells belong to smooth muscle. Correct answer: Smooth muscle. Cardiac cells are branched. Clinical: smooth muscle pathology affects vessel tone.

8) Clinical significance of cardiac muscle sheets:

a) Coordinated contraction of myocardium

b) Voluntary movements

c) Endocrine secretion

d) Filtration

Explanation: Sheet arrangement allows synchronized myocardial contraction. Correct answer: Coordinated contraction of myocardium. Clinical: disruption leads to inefficient pumping and heart failure.

9) Cardiac muscle striations are due to:

a) Sarcomeres

b) Fibrocartilage

c) Elastic fibers

d) Gap junctions

Explanation: Striations arise from organized sarcomeres with actin and myosin filaments. Correct answer: Sarcomeres. Clinical: sarcomere disruption occurs in cardiomyopathy.

10) Cardiac muscle differs from skeletal muscle in:

a) Branching and intercalated discs

b) Voluntary control

c) Peripheral nuclei

d) Non-striated appearance

Explanation: Cardiac muscle is branched, striated, and has intercalated discs, unlike skeletal muscle which is unbranched, striated, and multinucleated. Correct answer: Branching and intercalated discs. Clinical: these features enable synchronized contractions and resistance to mechanical stress.

Chapter: Muscle Physiology

Topic: Muscle Contraction

Subtopic: Tetanic Contraction and Ionic Basis

Keyword Definitions

• Tetanic contraction: Sustained maximal muscle tension produced by rapid repetitive stimulation.

• Calcium (Ca2+): Intracellular ion that enables cross-bridge cycling by binding to regulatory proteins.

• Summation: Successive twitches adding to increase tension when stimuli arrive before full relaxation.

• Sarcoplasmic reticulum: Organelle storing Ca2+ in muscle fibres and releasing it on stimulation.

• Excitation–contraction coupling: Sequence linking membrane depolarization to Ca2+ release and contraction.

Lead Question - 2012

Tetanic contraction is due to accumulation of ?

a) Na+

b) Ca2+

c) K+

d) Cl-

Explanation:

Tetanic contraction results when repeated stimuli cause intracellular calcium to accumulate because release from the sarcoplasmic reticulum outpaces reuptake; sustained Ca2+ keeps cross-bridges cycling and prevents relaxation. This leads to fused tetanus. Correct answer: Ca2+ (option b). Clinically relevant in high-frequency stimulation and some toxins.

Guessed Questions for NEET PG

1. Which process increases during unfused tetanus compared with single twitch?

a) Ca2+ reuptake

b) Summation of tension

c) Complete relaxation

d) Decreased cross-bridge cycling

Explanation:

Unfused tetanus arises when stimuli occur before full relaxation, so individual twitches summate producing increased mean tension. This summation occurs because residual Ca2+ persists between stimuli, increasing cross-bridge availability; it differs from fused tetanus where relaxation is absent. Correct answer: Summation of tension.

2. A toxin that blocks Ca2+ release would cause?

a) Enhanced tetanus

b) Flaccid paralysis

c) Spastic paralysis

d) Increased muscle tone

Explanation:

Blocking Ca2+ release from the sarcoplasmic reticulum prevents actin-myosin interaction, producing inability to generate force and flaccid paralysis. Without Ca2+, tetanic contraction cannot occur. Clinically, agents that prevent Ca2+ release produce muscle weakness rather than spasm. Correct answer: Flaccid paralysis.

3. Which ionic change primarily terminates contraction between twitches?

a) Increased intracellular Na+

b) Decrease in intracellular Ca2+ via reuptake

c) Increase in intracellular K+

d) Chloride influx

Explanation:

Contraction ends when Ca2+ is actively pumped back into the sarcoplasmic reticulum, lowering cytosolic Ca2+ and allowing regulatory proteins to inhibit cross-bridge formation, enabling relaxation. Efficient reuptake is essential to prevent summation. Correct answer: Decrease in intracellular Ca2+ via reuptake.

4. Which clinical condition produces sustained involuntary tetanic contractions?

a) Hypocalcemia increasing neuronal excitability

b) Hyperkalemia causing flaccidity

c) Botulism blocking ACh release

d) Myasthenia gravis reducing receptor sensitivity

Explanation:

Hypocalcemia lowers threshold for neuronal firing, potentially increasing neurotransmitter release and producing muscle hyperexcitability and tetany. These involuntary sustained contractions differ from tetanic contraction produced experimentally by high-frequency stimulation. Correct answer: Hypocalcemia increasing neuronal excitability.

5. During high-frequency stimulation fused tetanus occurs because?

a) SR reuptake accelerates

b) Cytosolic Ca2+ remains elevated between stimuli

c) Sarcomeres shorten beyond overlap optimum

d) ATP becomes unavailable instantly

Explanation:

Fused tetanus results when stimuli arrive so rapidly that cytosolic Ca2+ remains high continuously, preventing relaxation. Sustained cross-bridge cycling produces maximal, smooth contraction until fatigue or stimulus stops. Correct answer: Cytosolic Ca2+ remains elevated between stimuli.

6. Which mechanism contributes to muscle fatigue during prolonged tetanic contraction?

a) Unlimited ATP supply

b) Accumulation of inorganic phosphate and H+ impairing Ca2+ release and cross-bridges

c) Increased Ca2+ sensitivity of troponin

d) Enhanced SR Ca2+ content

Explanation:

Fatigue during sustained tetanus involves metabolic changes including inorganic phosphate and proton accumulation, which reduce calcium release and cross-bridge function, and impair ATPase activity, leading to declining force despite continued stimulation. Correct answer: Accumulation of inorganic phosphate and H+.

7. Which drug would reduce tetanic contraction by decreasing available Ca2+?

a) Ryanodine receptor agonist opening SR Ca2+ release

b) Dantrolene reducing SR Ca2+ release

c) ACh esterase inhibitor increasing ACh

d) Ca2+ ionophore increasing cytosolic Ca2+

Explanation:

Dantrolene inhibits calcium release from the sarcoplasmic reticulum, reducing intracellular Ca2+ and preventing sustained contractions, clinically used to treat malignant hyperthermia by suppressing excessive muscle contraction. Correct answer: Dantrolene reducing SR Ca2+ release.

8. In skeletal muscle physiology, accumulation of which ion extracellularly tends to reduce excitability rather than cause tetanus?

a) Extracellular K+ accumulation causing depolarization and inactivation of Na+ channels

b) Extracellular Ca2+ accumulation increasing contraction

c) Extracellular Na+ accumulation causing tetanus

d) Extracellular Cl- causing summation

Explanation:

Prolonged activity can raise extracellular K+, depolarizing the membrane and inactivating Na+ channels, reducing excitability and causing weakness, not tetanic contraction; tetanus arises from intracellular Ca2+ accumulation and high-frequency stimulation. Correct answer: Extracellular K+ accumulation causing depolarization and inactivation.

9. Which structural element directly binds Ca2+ to initiate contraction in skeletal muscle?

a) Troponin C on thin filaments

b) Myosin light chain kinase

c) Titin

d) Nebulin

Explanation:

In skeletal muscle, Ca2+ binds to troponin C in the thin filament regulatory complex causing conformational changes that allow myosin–actin interaction and force production; increased Ca2+ concentration from SR release initiates contraction and tetanus under repetitive stimuli. Correct answer: Troponin C.

10. Which experimental manipulation would most directly create fused tetanus in an isolated muscle preparation?

a) Low-frequency single pulses

b) High-frequency electrical stimulation preventing relaxation between pulses

c) Cooling the muscle to stop enzymatic activity

d) Blocking ACh receptors at the neuromuscular junction

Explanation:

Fused tetanus is produced experimentally by applying high-frequency stimuli such that Ca2+ accumulation prevents relaxation between pulses, resulting in sustained maximal tension, an established method to study contractile properties in isolated muscle. Correct answer: High-frequency electrical stimulation.

Chapter: Muscle Physiology

Topic: Length–Tension Relationship

Subtopic: Muscle Fibre Mechanics

Keyword Definitions:

• Optimum length – Muscle fibre length at which maximum tension is generated.

• Equilibrium length – Resting length without external load.

• Initial length – Starting length before contraction begins.

• Sarcomere – Basic contractile unit of a muscle fibre.

• Active tension – Force produced by cross-bridge cycling.

• Passive tension – Force developed when muscle is stretched beyond resting length.

Lead Question - 2012

When the tension in a muscle fibre is maximum, its length is called as ?

a) Equilibrium length

b) Optimum length

c) Initial length

d) None

Explanation:

Maximum muscle tension occurs at the optimum length, where actin–myosin overlap allows maximal cross-bridge formation. Too much shortening or stretching reduces tension. Hence, the correct answer is Optimum length.

Guessed Questions for NEET PG

1. At optimum length, sarcomere overlap is?

a) Complete overlap

b) Partial overlap allowing maximal cross-bridges

c) No overlap

d) Overlap beyond actin filaments

Explanation:

At optimum length, actin and myosin filaments overlap ideally, allowing maximum cross-bridge formation without hindrance. This ensures maximal tension development. Correct answer: Partial overlap allowing maximal cross-bridges.

2. Clinical: A patient with muscle spasm shows reduced force at very short length. Why?

a) Decreased calcium release

b) Overlap of actin filaments

c) Increased ATP consumption

d) Sarcomere hyperextension

Explanation:

At very short sarcomere lengths, actin filaments overlap excessively, blocking cross-bridge binding and reducing force generation. Correct answer: Overlap of actin filaments.

3. Passive tension in muscle arises mainly from?

a) Myosin heads

b) Actin filaments

c) Titin protein

d) Sarcoplasmic reticulum

Explanation:

When a muscle is stretched beyond resting length, passive tension develops due to titin and connective tissue elasticity. Correct answer: Titin protein.

4. Clinical: During physiotherapy, stretching muscles beyond resting length increases?

a) Active tension

b) Passive tension

c) Both active and passive equally

d) No change

Explanation:

Excessive stretching does not increase active tension but raises passive tension through elastic elements like titin. Correct answer: Passive tension.

5. Initial length of cardiac muscle fibres determines?

a) Contractility

b) Preload and stroke volume

c) Afterload

d) Heart rate

Explanation:

In the heart, initial muscle length (preload) sets sarcomere stretch, influencing stroke volume via the Frank–Starling mechanism. Correct answer: Preload and stroke volume.

6. In skeletal muscle, maximum active tension is observed at?

a) 1.6 µm sarcomere length

b) 2.0–2.2 µm sarcomere length

c) 3.5 µm sarcomere length

d) 1.0 µm sarcomere length

Explanation:

Studies show skeletal muscle develops maximal active tension when sarcomere length is 2.0–2.2 µm. Correct answer: 2.0–2.2 µm sarcomere length.

7. Clinical: Reduced cardiac contractility in dilated cardiomyopathy occurs because?

a) Sarcomeres overstretched

b) Increased overlap

c) ATP deficiency

d) Titin rupture

Explanation:

In dilated cardiomyopathy, sarcomeres are excessively stretched, reducing actin–myosin overlap and contractile efficiency. Correct answer: Sarcomeres overstretched.

8. What happens to active tension when muscle is stretched beyond optimum length?

a) Increases further

b) Decreases

c) Remains same

d) Shifts to passive

Explanation:

Beyond optimum length, overlap reduces, leading to fewer cross-bridges and decreased active tension, while passive tension increases. Correct answer: Decreases.

9. In isometric contraction at optimum length?

a) Tension is maximum

b) Length shortens maximally

c) Passive tension decreases

d) ATP consumption is minimal

Explanation:

During isometric contraction, muscle length is fixed but tension peaks at optimum sarcomere length. Correct answer: Tension is maximum.

10. Clinical: After immobilization, muscles lose optimum length efficiency due to?

a) Reduced sarcomere number

b) Increased titin length

c) Hyperplasia of fibres

d) Myelin degeneration

Explanation:

Immobilization leads to sarcomere loss, altering optimum length and reducing force output. Correct answer: Reduced sarcomere number.

Chapter: Physiology

Topic: Muscle Physiology

Subtopic: Smooth vs Skeletal Muscle

Keyword Definitions:

• Smooth muscle – Involuntary muscle controlled by autonomic nervous system and hormones.

• Skeletal muscle – Voluntary muscle controlled by somatic nervous system.

• Calcium ions – Required for contraction in both smooth and skeletal muscle, though mechanism differs.

• Troponin – Regulatory protein present in skeletal but absent in smooth muscle.

• Myosin – Thick filament protein essential for contraction in all muscles.

Lead Question - 2012

Smooth muscle physiology different from skeletal muscle

a) K⁺ requires for contraction

b) Ca²⁺ required for contraction

c) Troponin is absent

d) Myosin is required for contraction

Explanation:

Smooth muscle differs from skeletal muscle mainly due to the absence of troponin. Instead, smooth muscle contraction is regulated by calmodulin–myosin light chain kinase pathway. Calcium still plays a key role, but the regulatory protein troponin is absent. Correct answer: Troponin is absent.

Guessed Questions for NEET PG

1. Smooth muscle contraction is regulated by?

a) Troponin

b) Calmodulin

c) Tropomyosin

d) Titin

Explanation:

Unlike skeletal muscle, smooth muscle lacks troponin. Instead, contraction is controlled by calcium–calmodulin complex which activates myosin light chain kinase. Correct answer: Calmodulin.

2. Which protein is absent in smooth muscle fibers?

a) Actin

b) Troponin

c) Myosin

d) Tropomyosin

Explanation:

Actin, myosin, and tropomyosin are present in smooth muscle. Troponin, however, is absent, which differentiates it from skeletal muscle. Correct answer: Troponin.

3. Calcium in smooth muscle binds to?

a) Troponin C

b) Calmodulin

c) Tropomyosin

d) Actinin

Explanation:

In skeletal muscle, calcium binds troponin C, but in smooth muscle it binds to calmodulin, initiating contraction via MLCK. Correct answer: Calmodulin.

4. Patient with asthma receives bronchodilator. Relaxation of airway smooth muscle occurs by?

a) Increased cAMP

b) Increased IP₃

c) Increased calcium

d) Decreased cAMP

Explanation:

β₂ agonists increase cAMP, which inhibits MLCK, leading to relaxation of smooth muscle in bronchi. Correct answer: Increased cAMP.

5. Dense bodies in smooth muscle are functionally similar to?

a) T-tubules

b) Z-lines

c) Sarcoplasmic reticulum

d) Myosin heads

Explanation:

Dense bodies in smooth muscle anchor thin filaments, serving a role similar to Z-lines in skeletal muscle. Correct answer: Z-lines.

6. Which of the following best describes latch phenomenon in smooth muscle?

a) Sustained contraction with high ATP

b) Sustained contraction with low ATP

c) Rapid relaxation

d) Skeletal-type tetany

Explanation:

Latch phenomenon allows smooth muscle to maintain tension for long periods with minimal ATP use. Correct answer: Sustained contraction with low ATP.

7. In smooth muscle, myosin light chain kinase (MLCK) is activated by?

a) Troponin C

b) Calcium–calmodulin

c) Tropomyosin

d) ATP alone

Explanation:

Calcium binds calmodulin which activates MLCK, phosphorylating myosin light chains to initiate contraction. Correct answer: Calcium–calmodulin.

8. Clinical: A hypertensive patient takes a calcium channel blocker. Effect on vascular smooth muscle?

a) Increased contraction

b) Decreased contraction

c) Increased MLCK activity

d) Increased calcium influx

Explanation:

Calcium channel blockers reduce calcium influx into smooth muscle, lowering contraction and relaxing vessels. Correct answer: Decreased contraction.

9. Skeletal and smooth muscle differ because skeletal muscle contraction is?

a) Involuntary and calmodulin-mediated

b) Voluntary and troponin-mediated

c) Involuntary and troponin-mediated

d) Voluntary and calmodulin-mediated

Explanation:

Skeletal muscle is voluntary and regulated by troponin–tropomyosin complex, unlike smooth muscle. Correct answer: Voluntary and troponin-mediated.

10. Which structural arrangement is absent in smooth muscle compared to skeletal?

a) Sarcomere

b) Myosin

c) Actin

d) Intermediate filaments

Explanation:

Smooth muscle lacks sarcomere arrangement, hence appears non-striated. Myosin, actin, and intermediate filaments are present. Correct answer: Sarcomere.

Chapter: Lower Limb Anatomy
Topic: Hip Joint & Thigh Muscles
Subtopic: Hip Flexors — Actions and Clinical Relevance

Keyword Definitions

• Psoas major — Primary hip flexor arising from lumbar vertebrae; strong hip flexion and trunk flexion contribution.

• Iliacus — Joins psoas major to form iliopsoas, major hip flexor inserting on lesser trochanter.

• Iliopsoas — Combined tendon of psoas major and iliacus; principal flexor of hip.

• Biceps femoris — Hamstring muscle; knee flexor and hip extensor (long head) — not primary hip flexor.

• Gluteus maximus — Principal hip extensor and external rotator; active in rising from sitting.

• Tensor fasciae latae (TFL) — Assists hip flexion, abduction, and medial rotation; acts via IT band.

• Hip flexion — Movement decreasing angle between thigh and trunk; important for walking, climbing stairs.

• Femoral nerve — Supplies iliacus and provides motor to quadriceps; psoas major supplied by lumbar plexus.

• Hip pathology — Iliopsoas bursitis or tendonitis causes anterior hip pain aggravated by flexion.

• Clinical test — Straight leg raise and resisted hip flexion assess iliopsoas function.

Lead Question - 2012

Muscle causing flexion of hip ?

• a) Biceps femoris

• b) Psoas major

• c) Gluteus maximus

• d) TFL

Explanation: The psoas major, together with iliacus (forming iliopsoas), is the principal hip flexor producing powerful flexion at the hip and contributing to trunk flexion. Biceps femoris and gluteus maximus are extensors; TFL assists flexion but is not the primary flexor. Answer: b) Psoas major.

1. Primary nerve supply to psoas major is from:

• a) Femoral nerve

• b) Lumbar plexus (L1–L3)

• c) Sciatic nerve

• d) Superior gluteal nerve

Explanation: Psoas major receives direct branches from the anterior rami of lumbar spinal nerves (L1–L3) constituting part of the lumbar plexus. Femoral nerve supplies iliacus; sciatic and superior gluteal do not innervate psoas. Clinically lumbar radiculopathy affects hip flexion. Answer: b) Lumbar plexus (L1–L3).

2. Iliopsoas tendonitis typically causes pain at:

• a) Posterior thigh

• b) Anterior groin/hip

• c) Lateral knee

• d) Medial ankle

Explanation: Iliopsoas tendonitis presents with anterior groin or hip pain aggravated by hip flexion, resisted straight leg raise, and climbing stairs. It may mimic intra-articular hip pathology; ultrasound or MRI helps confirm tendon inflammation. Answer: b) Anterior groin/hip.

3. Which muscle is a synergist to psoas major in hip flexion?

• a) Gluteus maximus

• b) Rectus femoris

• c) Adductor magnus

• d) Piriformis

Explanation: Rectus femoris (part of quadriceps) crosses the hip and assists in hip flexion, acting as a synergist to iliopsoas during activities requiring powerful hip flexion like kicking. Gluteus maximus is an extensor. Answer: b) Rectus femoris.

4. A patient cannot flex hip against resistance but can on gravity-eliminated plane. This suggests:

• a) Complete nerve transection

• b) Pain inhibition or partial weakness

• c) Intact motor function

• d) Labral tear

Explanation: Inability to perform resisted hip flexion with preserved movement on gravity-eliminated testing suggests pain inhibition or partial weakness (Grade 3/5), not complete denervation. Further neuro exam and imaging are warranted. Answer: b) Pain inhibition or partial weakness.

5. InTrendelenburg gait is due to weakness of:

• a) Hip flexors (psoas)

• b) Hip abductors (gluteus medius/minimus)

• c) Knee extensors (quadriceps)

• d) Ankle dorsiflexors

Explanation: Trendelenburg gait arises from weak hip abductors (gluteus medius/minimus) causing pelvic drop on contralateral side during stance. Psoas weakness causes hip flexion issues but not Trendelenburg. Examination differentiates abductor from flexor pathology. Answer: b) Hip abductors (gluteus medius/minimus).

6. Which motion is produced when iliopsoas acts bilaterally on fixed femur?

• a) Trunk extension

• b) Trunk flexion (sit-up)

• c) Lateral rotation of femur

• d) Hip abduction

Explanation: With femur fixed, bilateral contraction of iliopsoas flexes the trunk at the hip (raises the torso), assisting in sit-up movements. It also stabilizes lumbar spine during posture. Dysfunction impairs rising from supine. Answer: b) Trunk flexion (sit-up).

7. Which muscle primarily extends the hip and opposes psoas major?

• a) Iliacus

• b) Gluteus maximus

• c) Sartorius

• d) Pectineus

Explanation: Gluteus maximus is the main hip extensor providing power for rising, climbing, and sprinting, functionally opposing the flexion produced by iliopsoas. Injury to gluteus maximus alters gait and seated-to-standing mechanics. Answer: b) Gluteus maximus.

8. Tight psoas major may cause which postural change?

• a) Increased lumbar lordosis

• b) Flattened lumbar curve

• c) Thoracic kyphosis reduction

• d) Knee hyperextension

Explanation: A tight psoas pulls lumbar spine into increased lordosis and anterior pelvic tilt, contributing to low back pain and altered gait mechanics. Stretching and posture correction are part of management. Answer: a) Increased lumbar lordosis.

9. Hip flexion power is most compromised by lesion of which structure?

• a) Femoral nerve root (L2–L4)

• b) Sciatic nerve

• c) Obturator nerve

• d) Superior gluteal nerve

Explanation: The femoral nerve innervates iliacus and rectus femoris; lesion reduces hip flexion strength. Psoas major is from lumbar plexus; combined lesions of L2–L4 significantly impair hip flexion. Sciatic/obturator/gluteal affect other functions. Answer: a) Femoral nerve root (L2–L4).

10. Clinical test for iliopsoas strength: patient performs?

• a) Hip abduction against resistance

• b) Resisted hip flexion in sitting or supine

• c) Heel raise

• d) Knee flexion

Explanation: Resisted hip flexion (patient attempts to lift thigh against resistance) assesses iliopsoas/rectus femoris. Positive pain or weakness suggests tendonitis, nerve lesion, or muscular tear and guides further imaging or EMG. Answer: b) Resisted hip flexion in sitting or supine.

Chapter: Head & Neck Anatomy
Topic: Facial Muscles

Subtopic: Risorius — anatomy, function, and clinical relevance

Keyword Definitions

• Risorius — thin superficial facial muscle that retracts the angle of the mouth producing a smile or grimace.

• Facial expression muscles — group of muscles innervated by the facial nerve (CN VII) that move the skin of the face.

• Mastication muscles — muscles of chewing (masseter, temporalis, pterygoids) innervated by V3, not risorius.

• Buccinator — deep cheek muscle that compresses the cheek and assists in mastication; distinct from risorius.

• Facial nerve (CN VII) — motor nerve supplying muscles of facial expression including risorius; vulnerable in parotid surgery.

• Parotid gland/plexus — risorius lies superficially near parotid region; surgical injury may affect branches of CN VII causing asymmetry.

• Botulinum toxin — used cosmetically/therapeutically on facial muscles; improper injection into risorius can alter smile.

• Deglutition — swallowing; risorius is not a primary deglutition muscle.

• Orbicularis oris — sphincter muscle of the mouth working with risorius for lip movement.

• Clinical sign — loss of risorius function causes inability to retract mouth corner, mild asymmetrical smile.

Lead Question - 2012

Risorius is a muscle of ?

• a) Mastication

• b) Deglutition

• c) Facial expression

• d) Eye movement

Explanation: Risorius is a superficial muscle of facial expression that retracts the angle of the mouth laterally, contributing to smiling or grimacing. It is innervated by branches of the facial nerve (CN VII) and not involved in mastication, swallowing, or eye movement. Answer: c) Facial expression.

1. Which nerve supplies the risorius muscle?

• a) Mandibular division of trigeminal (V3)

• b) Facial nerve (CN VII)

• c) Hypoglossal nerve (XII)

• d) Glossopharyngeal nerve (IX)

Explanation: The risorius receives motor innervation from the facial nerve (CN VII) via its buccal or zygomatic branches. Damage to these branches (eg. parotid surgery) produces weakness of mouth corner retraction and a flattened or asymmetrical smile. Answer: b) Facial nerve (CN VII).

2. Primary action of risorius is to:

• a) Elevate mandible

• b) Protrude tongue

• c) Retract angle of mouth laterally

• d) Close eyelids

Explanation: Risorius retracts the angle of the mouth laterally, creating a grin or stretched smile. It acts with levator and depressor muscles to modulate facial expression. It does not elevate the mandible, move the tongue, or close eyelids. Answer: c) Retract angle of mouth laterally.

3. Injury to the facial nerve branch supplying risorius produces which clinical sign?

• a) Difficulty in chewing

• b) Loss of forehead wrinkling

• c) Asymmetrical smile with inability to retract mouth corner

• d) Diplopia

Explanation: Paralysis of the branch to risorius causes inability to retract the mouth corner on the affected side, producing an asymmetrical smile. Chewing is mainly V3, forehead wrinkling involves temporal branch, and diplopia relates to ocular muscles. Answer: c) Asymmetrical smile with inability to retract mouth corner.

4. During parotid surgery, which precaution least helps preserve risorius function?

• a) Identify and protect facial nerve branches

• b) Minimize traction on superficial fascia

• c) Avoid deep incisions through masseter

• d) Only operate via transoral approach crossing buccinator

Explanation: Preserving facial nerve branches and superficial fascia protects risorius. A transoral approach through buccinator (d) risks injuring branches and the duct, making it least protective. Avoiding deep masseter incisions is sensible. Answer: d) Only operate via transoral approach crossing buccinator.

5. Which muscle lies deep to risorius and assists cheek flattening during mastication?

• a) Buccinator

• b) Masseter

• c) Platysma

• d) Levator labii superioris

Explanation: Buccinator lies deep to risorius and compresses the cheek to keep food between teeth, aiding mastication. Masseter is a primary masticator on lateral face. Risorius superficially retracts mouth corner and does not assist primary chewing. Answer: a) Buccinator.

6. Cosmetic injection of botulinum toxin into risorius is used to treat:

• a) Jaw claudication

• b) Gummy smile due to hyperactive smiling muscles

• c) Orbital cellulitis

• d) Vocal cord paralysis

Explanation: Botulinum toxin into risorius and adjacent smile muscles can reduce hyperactive lateral mouth retraction contributing to a gummy or asymmetrical smile. Careful dosing prevents excessive weakness and smile distortion. It is not used for orbital cellulitis or vocal cord issues. Answer: b) Gummy smile due to hyperactive smiling muscles.

7. Anatomical variation: risorius commonly inserts into:

• a) Skin at angle of mouth

• b) Mandibular ramus

• c) Zygomatic arch

• d) Hyoid bone

Explanation: Risorius inserts into the skin at the angle of mouth (modiolus area), pulling it laterally. It does not attach to bony structures like the mandible, zygoma, or hyoid. Variations in origin exist but insertion is cutaneous. Answer: a) Skin at angle of mouth.

8. Which clinical test assesses risorius function specifically?

• a) Puff cheeks against closed lips

• b) Ask patient to show teeth and retract mouth corners laterally

• c) Test tongue protrusion

• d) Assess shoulder shrug

Explanation: Asking the patient to smile broadly and retract mouth corners tests risorius among other smile muscles; inability to retract the affected corner suggests weakness. Puffing cheeks tests buccinator and orbicularis, tongue relates to XII, shoulder shrug to accessory nerve. Answer: b) Ask patient to show teeth and retract mouth corners laterally.

9. In facial nerve palsy localized to the buccal branches, which action is most compromised?

• a) Eye closure

• b) Nasolabial fold flattening and mouth corner retraction

• c) Head rotation

• d) Tongue movement

Explanation: Buccal branches supply muscles of the midface including risorius, buccinator, and orbicularis oris; palsy flattens nasolabial fold and impairs mouth corner retraction and labial competence. Eye closure is temporal/zygomatic, head rotation accessory. Answer: b) Nasolabial fold flattening and mouth corner retraction.

10. Which statement about risorius is FALSE?

• a) It is a muscle of facial expression

• b) It aids chewing by elevating mandible

• c) It is innervated by CN VII

• d) It inserts into skin at mouth angle

Explanation: Risorius does not aid mastication or elevate the mandible; that is the role of masseter and temporalis. Risorius retracts mouth angle, is innervated by facial nerve, and inserts into the skin at the angle of the mouth. Answer: b) It aids chewing by elevating mandible (FALSE).

Chapter: Pharynx
Topic: Pharyngeal Muscles
Subtopic: Passavant's Ridge

Keyword Definitions:

• Passavant's Ridge: A mucosal ridge on the posterior pharyngeal wall during swallowing.

• Superior Constrictor: Muscle forming posterior pharyngeal wall, contributes to ridge formation.

• Palatopharyngeus: Elevates pharynx and contributes fibers to ridge.

• Palatoglossus: Muscle connecting tongue to palate, not involved in ridge.

• Inferior Constrictor: Pharyngeal constrictor muscle, not part of ridge formation.

• Soft Palate: Muscular fold that closes nasopharynx during swallowing.

Lead Question – 2012

Passavant ridge ?

• a) Superior constrictor and palatopharyngeus

• b) Inferior constrictor and palatopharyngeus

• c) Superior constrictor and palatoglossus

• d) Inferior constrictor and palatoglossus

Explanation: Passavant’s ridge is a mucosal prominence formed by contraction of the superior constrictor and palatopharyngeus during swallowing. It helps close the nasopharyngeal isthmus against the soft palate, preventing nasal regurgitation. Correct answer: a) Superior constrictor and palatopharyngeus.

Question 2. A patient presents with nasal regurgitation of liquids. Dysfunction of which structure is most likely?

• a) Palatoglossus

• b) Passavant’s ridge

• c) Cricopharyngeus

• d) Stylopharyngeus

Explanation: Failure of Passavant’s ridge to form properly prevents closure of nasopharynx, causing nasal regurgitation. This occurs with superior constrictor or palatopharyngeus weakness. Correct answer: b) Passavant’s ridge.

Question 3. Which muscle is primarily responsible for preventing food from entering the nasopharynx?

• a) Tensor veli palatini

• b) Levator veli palatini

• c) Palatopharyngeus

• d) Stylopharyngeus

Explanation: Levator veli palatini elevates the soft palate, sealing the nasopharynx against Passavant’s ridge. This prevents regurgitation during swallowing. Correct answer: b) Levator veli palatini.

Question 4. A lesion of glossopharyngeal nerve will most likely cause?

• a) Absent gag reflex

• b) Nasal regurgitation

• c) Hoarseness

• d) Shoulder droop

Explanation: Glossopharyngeal nerve supplies sensory input for gag reflex. Its lesion abolishes gag reflex while motor defects are due to vagus/accessory nerve. Correct answer: a) Absent gag reflex.

Question 5. Inadequate closure of the nasopharynx during swallowing is due to paralysis of?

• a) Palatopharyngeus

• b) Stylopharyngeus

• c) Masseter

• d) Cricopharyngeus

Explanation: Palatopharyngeus elevates pharynx and forms Passavant’s ridge. Its dysfunction leads to failure of nasopharyngeal closure. Correct answer: a) Palatopharyngeus.

Question 6. A child with cleft palate develops hypernasal speech. The main cause is?

• a) Weak palatal closure

• b) Weak tongue movement

• c) Laryngeal stenosis

• d) Weak jaw closure

Explanation: Hypernasality results from failure of palatal muscles and Passavant’s ridge to close the nasopharyngeal opening during speech. Correct answer: a) Weak palatal closure.

Question 7. Which nerve mediates motor supply to palatal muscles except tensor veli palatini?

• a) Glossopharyngeal

• b) Vagus via cranial accessory

• c) Trigeminal mandibular

• d) Hypoglossal

Explanation: All palatal muscles except tensor veli palatini are supplied by vagus through cranial part of accessory nerve. Correct answer: b) Vagus via cranial accessory.

Question 8. Which muscle is supplied by mandibular nerve among palatal muscles?

• a) Levator veli palatini

• b) Tensor veli palatini

• c) Palatopharyngeus

• d) Palatoglossus

Explanation: Tensor veli palatini is the only palatal muscle supplied by mandibular division of trigeminal nerve. Correct answer: b) Tensor veli palatini.

Question 9. A 40-year-old develops difficulty swallowing with nasal escape of food. Which nerve is most likely affected?

• a) Vagus

• b) Hypoglossal

• c) Facial

• d) Glossopharyngeal

Explanation: Vagus nerve supplies motor fibers to palatal muscles (via cranial accessory). Its lesion causes palatal paralysis and nasal regurgitation. Correct answer: a) Vagus.

Question 10. Which muscle contributes to Passavant’s ridge along with superior constrictor?

• a) Palatopharyngeus

• b) Palatoglossus

• c) Stylopharyngeus

• d) Tensor veli palatini

Explanation: Passavant’s ridge is formed by palatopharyngeus fibers joining superior constrictor contraction. Correct answer: a) Palatopharyngeus.

Question 11. A surgeon notes poor closure of nasopharynx after adenoidectomy. Which structure is compromised?

• a) Passavant’s ridge

• b) Cricopharyngeus

• c) Stylopharyngeus

• d) Tensor veli tympani

Explanation: If Passavant’s ridge or its contributing muscles are injured, nasopharyngeal closure fails, leading to regurgitation or hypernasal speech. Correct answer: a) Passavant’s ridge.

Triangle of Auscultation: A small triangular area on the back where the thoracic wall is thin, allowing clear lung auscultation.

Trapezius: Large superficial muscle of the back responsible for moving the scapula and supporting arm movements.

Latissimus Dorsi: Broad, flat muscle covering lower back; involved in arm adduction, extension, and internal rotation.

Rhomboid Major: Muscle connecting spine to scapula, retracting and stabilizing the scapula.

Scapula: Shoulder blade bone, forms part of the shoulder girdle; not a muscular boundary.

Chapter: Anatomy

Topic: Back Muscles

Subtopic: Triangle of Auscultation

Lead Question 2012: All form boundaries of triangle of auscultation except:

a) Trapezius

b) Latissmusdorsi

c) Scapula

d) Rhomboid major

Answer: c) Scapula

Explanation: The triangle of auscultation is bordered by the **trapezius** medially, **rhomboid major** laterally, and **latissimus dorsi** inferiorly. The scapula is a bone overlying the area, not a muscular boundary. Clinically, this triangle is important because placing a stethoscope here allows better auscultation of lung sounds due to reduced muscular thickness.

1. Which muscle forms the medial border of the triangle of auscultation?

a) Rhomboid major

b) Trapezius

c) Latissimus dorsi

d) Serratus anterior

Answer: b) Trapezius

Explanation: The medial border of the triangle of auscultation is formed by the **trapezius**. This muscle extends from the occipital bone to the lower thoracic vertebrae, covering part of the back. Its lateral border is formed by rhomboid major, and inferiorly by latissimus dorsi.

2. The inferior boundary of the triangle of auscultation is formed by:

a) Latissimus dorsi

b) Trapezius

c) Rhomboid minor

d) Erector spinae

Answer: a) Latissimus dorsi

Explanation: The **latissimus dorsi** forms the inferior boundary of the triangle. It is a broad, flat muscle involved in arm adduction, extension, and medial rotation. Its position makes the area thin and suitable for auscultating lung sounds clinically.

3. Lateral border of the triangle of auscultation is formed by:

a) Trapezius

b) Rhomboid major

c) Serratus posterior superior

d) Levator scapulae

Answer: b) Rhomboid major

Explanation: The **rhomboid major** forms the lateral border of the triangle of auscultation. It retracts and stabilizes the scapula, and its thin overlay in this area allows better lung auscultation. Trapezius is medial, latissimus dorsi is inferior.

4. Clinically, why is the triangle of auscultation important?

a) Muscle injection site

b) Better lung auscultation

c) Site for nerve block

d) Bone palpation

Answer: b) Better lung auscultation

Explanation: The triangle of auscultation is a clinically significant area because muscular thickness is minimal, allowing stethoscopes to detect lung sounds clearly. Physicians often ask patients to fold arms over chest to enlarge the triangle for auscultation.

5. Which posture enlarges the triangle of auscultation for examination?

a) Arms at sides

b) Hands behind head

c) Hands folded across chest

d) Forward bending

Answer: c) Hands folded across chest

Explanation: Folding the arms across the chest rotates the scapula laterally, widening the triangle of auscultation. This allows easier placement of the stethoscope for clear lung sound assessment. Forward bending or arms behind head do not effectively enlarge the area.

6. Which nerve is closely related to the triangle of auscultation?

a) Long thoracic nerve

b) Thoracodorsal nerve

c) Spinal accessory nerve

d) Axillary nerve

Answer: a) Long thoracic nerve

Explanation: The **long thoracic nerve** runs along the lateral chest wall near the triangle, innervating serratus anterior. Injury can cause winged scapula. Awareness of nearby nerves is important during clinical procedures in the area.

7. Which imaging modality can show muscles forming the triangle of auscultation?

a) X-ray

b) MRI

c) Ultrasound

d) CT scan

Answer: b) MRI

Explanation: MRI can clearly visualize soft tissues including trapezius, rhomboid major, and latissimus dorsi, demonstrating the triangle of auscultation. Ultrasound can also be used, but X-ray shows only bones. CT scan is less commonly used for muscle visualization.

8. Which condition can make auscultation through this triangle more difficult?

a) Muscle hypertrophy

b) Muscle atrophy

c) Thin body habitus

d) Forward flexion

Answer: a) Muscle hypertrophy

Explanation: Hypertrophy of trapezius, rhomboid, or latissimus dorsi increases muscle thickness, making lung auscultation more difficult. Thin body habitus enhances auscultation. Clinical positioning can compensate partially, but hypertrophy reduces the acoustic window.

9. Which muscle is superficial and must be displaced to access the triangle?

a) Trapezius

b) Rhomboid minor

c) Levator scapulae

d) Serratus anterior

Answer: a) Trapezius

Explanation: The trapezius is superficial and overlies part of the triangle. During clinical examination, scapular rotation moves the trapezius laterally, allowing access to the triangle of auscultation. Deep muscles like rhomboid minor remain under trapezius.

10. Which movement of the scapula enlarges the triangle laterally?

a) Elevation

b) Retraction

c) Protraction

d) Depression

Answer: c) Protraction

Explanation: Lateral protraction of the scapula moves it away from the vertebral column, widening the triangle of auscultation. This facilitates auscultation. Retraction or elevation reduces the area, making examination more difficult.

Keyword Definitions:

• Pelvic Stability: Ability to maintain pelvis alignment during walking or standing to prevent tilting.

• Gluteus Medius & Minimus: Hip abductor muscles crucial for stabilizing pelvis during gait.

• Trendelenburg Gait: Abnormal gait caused by weakness of gluteus medius/minimus.

• Hip Abduction: Movement of the leg away from the midline, important in walking stability.

• Gait Cycle: The sequence of motions during walking, divided into stance and swing phases.

• Quadriceps: Group of thigh muscles involved in knee extension and stabilization during walking.

• Adductors: Muscles bringing the thigh towards the body's midline.

• Pelvic Tilt: Movement of the pelvis in the sagittal or frontal plane affecting gait mechanics.

Chapter: Locomotion and Movement
Topic: Gait and Muscle Actions
Sub-topic: Pelvic Stability During Walking

Lead Question (2012):

42. In walking, gravity tends to tilt pelvis and trunk to the unsupported side, major factor in preventing this unwanted movement is?

a) Adductor muscles

b) Quadriceps

c) Gluteus maximus

d) Gluteus medius and minimus

Explanation: The gluteus medius and minimus are primary hip abductors that stabilize the pelvis during the stance phase of gait. When one leg is lifted, these muscles on the opposite side contract to prevent pelvic drop. Weakness results in Trendelenburg gait. Adductors, quadriceps, and gluteus maximus have other roles in walking but do not provide primary pelvic stability in this context. Correct Answer: d) Gluteus medius and minimus

1. A patient presents with a waddling gait and difficulty maintaining pelvic level while walking. Which muscle weakness is most likely responsible?
a) Gluteus medius
b) Rectus femoris
c) Sartorius
d) Iliopsoas

Explanation: Waddling gait and pelvic drop point to gluteus medius weakness. This muscle functions as a pelvic stabilizer during the stance phase. Rectus femoris is mainly for knee extension and hip flexion, sartorius assists in flexion/abduction, and iliopsoas is the primary hip flexor. Correct Answer: a) Gluteus medius

2. Trendelenburg test is used to assess the integrity of which nerve?
a) Femoral nerve
b) Obturator nerve
c) Superior gluteal nerve
d) Inferior gluteal nerve

Explanation: The superior gluteal nerve innervates the gluteus medius and minimus. Damage causes positive Trendelenburg sign due to pelvic drop on the contralateral side during single-leg stance. The femoral nerve supplies anterior thigh muscles, obturator nerve supplies adductors, and inferior gluteal nerve supplies gluteus maximus. Correct Answer: c) Superior gluteal nerve

3. During walking, in which phase do the gluteus medius and minimus contract most strongly?
a) Swing phase
b) Stance phase
c) Toe-off phase
d) Double support phase

Explanation: Hip abductors like gluteus medius and minimus are most active during the stance phase when the opposite leg is in the swing phase. This activity prevents pelvic drop toward the unsupported side. In the swing phase, these muscles are less active. Correct Answer: b) Stance phase

4. A clinical student notes that a patient’s pelvis drops to the left during right leg stance. This indicates weakness in:
a) Left gluteus medius
b) Right gluteus medius
c) Right gluteus maximus
d) Left gluteus maximus

Explanation: Pelvic drop occurs on the side opposite to the weak muscle. If pelvis drops to the left, the right gluteus medius is weak. This is because the right hip abductors should hold the pelvis level when the right leg bears weight. Correct Answer: b) Right gluteus medius

5. Which of the following muscles assists the gluteus medius in pelvic stabilization?
a) Tensor fasciae latae
b) Biceps femoris
c) Semitendinosus
d) Gastrocnemius

Explanation: The tensor fasciae latae assists the gluteus medius in hip abduction and pelvic stabilization during gait. Biceps femoris and semitendinosus are hamstring muscles, while gastrocnemius is a calf muscle. Correct Answer: a) Tensor fasciae latae

6. In a patient with a superior gluteal nerve injury, which gait abnormality is most expected?
a) Steppage gait
b) Antalgic gait
c) Trendelenburg gait
d) Ataxic gait

Explanation: Superior gluteal nerve injury weakens the gluteus medius and minimus, leading to Trendelenburg gait — characterized by pelvic drop on the unsupported side during walking. Steppage gait is seen in foot drop, antalgic gait in pain, and ataxic gait in cerebellar disorders. Correct Answer: c) Trendelenburg gait

7. Which muscle is primarily responsible for preventing excessive pelvic tilt in the coronal plane during single-leg stance?
a) Piriformis
b) Gluteus maximus
c) Gluteus medius
d) Iliacus

Explanation: The gluteus medius is the primary stabilizer preventing excessive pelvic tilt in the coronal plane during single-leg stance. Piriformis assists in lateral rotation, gluteus maximus in hip extension, and iliacus in hip flexion. Correct Answer: c) Gluteus medius

8. A 45-year-old patient has difficulty climbing stairs after hip surgery. Which muscle weakness is most likely if pelvic stability is also compromised?
a) Quadriceps femoris
b) Gluteus medius
c) Adductor magnus
d) Sartorius

Explanation: Gluteus medius weakness affects both stair climbing and pelvic stability. Quadriceps mainly extend the knee, adductor magnus brings the leg toward midline, and sartorius flexes the hip and knee but does not stabilize pelvis effectively. Correct Answer: b) Gluteus medius

9. Which muscle group counteracts gravity’s tendency to tilt the pelvis during the gait cycle?
a) Hip abductors
b) Hip adductors
c) Knee extensors
d) Ankle plantarflexors

Explanation: Hip abductors (mainly gluteus medius and minimus) counteract gravity’s pull, keeping pelvis level during stance phase. Adductors, knee extensors, and ankle plantarflexors serve other roles in gait mechanics. Correct Answer: a) Hip abductors

10. A physiotherapist is retraining a stroke patient’s gait. To strengthen pelvic stability, which exercise is most appropriate?
a) Side-lying hip abduction
b) Leg press
c) Calf raises
d) Hamstring curls

Explanation: Side-lying hip abduction specifically targets the gluteus medius and minimus, enhancing pelvic stability during walking. Leg press works mainly quadriceps, calf raises target gastrocnemius/soleus, and hamstring curls strengthen posterior thigh muscles. Correct Answer: a) Side-lying hip abduction

Keywords & Definitions:

• Popliteus muscle: A small muscle located at the back of the knee joint, playing a role in unlocking the knee from a fully extended position.

• Knee joint: A hinge-type synovial joint connecting the femur, tibia, and patella, allowing flexion and extension.

• Intracapsular origin: A muscle origin point located within the fibrous capsule of a joint.

• Tibial nerve: A branch of the sciatic nerve supplying motor and sensory innervation to parts of the leg and foot.

• Knee locking: A mechanism that stabilizes the knee in extension by medial rotation of the femur on the tibia.

• Flexor muscles of knee: Muscles that bend the knee joint, reducing the angle between the thigh and leg.

• Posterior cruciate ligament: A ligament inside the knee joint that prevents posterior displacement of the tibia.

• Meniscus: C-shaped fibrocartilage structures that provide cushioning and stability in the knee joint.

• Lateral rotation of femur: Outward movement of the femur around its longitudinal axis, important in knee biomechanics.

• Bursitis: Inflammation of the bursa, a small fluid-filled sac reducing friction between tissues.

Chapter: Locomotor System – Lower Limb Anatomy
Topic: Muscles of the Leg
Sub-topic: Popliteus Muscle Anatomy and Function

Lead Question – NEET PG 2012:

True about popliteus are all except?

a) Flexor of knee

b) Intracapsular origin

c) Supplied by tibial nerve

d) Causes locking of knee

Explanation:

The popliteus muscle is a flexor of the knee, originates intracapsularly from the lateral femoral condyle, and is supplied by the tibial nerve. However, it causes unlocking of the knee by laterally rotating the femur on the tibia during initiation of flexion. The locking function is opposite to its role. Correct answer: d) Causes locking of knee.

Guess Question 1:
Which nerve injury can lead to weakness in unlocking the knee?
a) Common peroneal nerve
b) Tibial nerve
c) Femoral nerve
d) Obturator nerve

Explanation: The tibial nerve innervates the popliteus muscle, crucial for unlocking the knee. Injury to this nerve impairs flexion initiation from a fully extended position, causing difficulty in walking downstairs or on slopes. Correct answer: b) Tibial nerve.

Guess Question 2:
The popliteus muscle primarily acts by:
a) Medially rotating the tibia
b) Laterally rotating the femur
c) Abducting the tibia
d) Extending the knee

Explanation: The popliteus muscle unlocks the knee by laterally rotating the femur on the tibia when the foot is fixed, or medially rotating the tibia when the foot is free. This breaks the 'screw-home' mechanism of knee locking. Correct answer: b) Laterally rotating the femur.

Guess Question 3:
Which structure is located anterior to the popliteus muscle?
a) Lateral meniscus
b) Posterior cruciate ligament
c) Medial meniscus
d) Patellar ligament

Explanation: The posterior cruciate ligament lies anterior to the popliteus muscle within the knee joint capsule. This anatomical relationship is important during knee surgeries to avoid injury. Correct answer: b) Posterior cruciate ligament.

Guess Question 4:
Popliteus muscle origin is:
a) Medial femoral condyle
b) Lateral femoral condyle
c) Tibial plateau
d) Fibular head

Explanation: The popliteus originates from the lateral femoral condyle and adjacent lateral meniscus. Its tendon passes inferomedially through the capsule to insert on the posterior tibia. Correct answer: b) Lateral femoral condyle.

Guess Question 5:
Which artery supplies the popliteus muscle?
a) Femoral artery
b) Popliteal artery
c) Anterior tibial artery
d) Posterior tibial artery

Explanation: The popliteal artery, a continuation of the femoral artery, gives muscular branches to the popliteus. Adequate blood supply is essential for muscle function and healing post-injury. Correct answer: b) Popliteal artery.

Guess Question 6 (Clinical):
A patient with a posterior knee stab wound presents with difficulty in initiating knee flexion. Which muscle is likely injured?
a) Gastrocnemius
b) Popliteus
c) Semitendinosus
d) Biceps femoris

Explanation: The popliteus initiates flexion from full extension by unlocking the knee. Injury here causes functional impairment despite intact hamstrings. Correct answer: b) Popliteus.

Guess Question 7:
Which of the following is NOT an action of the popliteus muscle?
a) Unlocking the knee
b) Assisting knee flexion
c) Lateral rotation of femur
d) Knee extension

Explanation: The popliteus assists in flexion and unlocking the knee but does not extend the knee. Extension is achieved mainly by the quadriceps femoris. Correct answer: d) Knee extension.

Guess Question 8 (Clinical):
Damage to which ligament may impair popliteus function due to its attachment?
a) Anterior cruciate ligament
b) Posterior cruciate ligament
c) Lateral meniscus
d) Patellar ligament

Explanation: The popliteus has a fibrous attachment to the lateral meniscus. Damage here may affect both structures, leading to locking symptoms. Correct answer: c) Lateral meniscus.

Guess Question 9:
In a weight-bearing knee, the popliteus unlocks the joint by:
a) Medial rotation of femur
b) Lateral rotation of femur
c) Lateral rotation of tibia
d) Hyperextension

Explanation: In a fixed-foot condition, the popliteus laterally rotates the femur to unlock the knee. This movement is reversed when the tibia is free. Correct answer: b) Lateral rotation of femur.

Guess Question 10 (Clinical):
A patient recovering from knee arthroscopy has pain and weakness during the first 10° of flexion. Which muscle is primarily responsible for this movement?
a) Gastrocnemius
b) Hamstrings
c) Popliteus
d) Quadriceps femoris

Explanation: The popliteus is critical for initiating knee flexion from a locked position. Weakness here manifests as difficulty in starting flexion. Correct answer: c) Popliteus.

Chapter: Locomotion and Movement | Topic: Gait Cycle | Subtopic: Heel Touch Phase & Calf Compartment Pressure

Keywords:

• Heel Touch Phase - Initial phase of gait cycle when the heel makes contact with the ground.

• Calf Compartment - Posterior compartment of the leg containing gastrocnemius, soleus, and other muscles, enclosed by fascia.

• Resting Pressure - The baseline pressure within a closed anatomical compartment at rest.

• Compartment Pressure - Pressure within an enclosed myofascial compartment, influenced by muscle activity and blood flow.

• Gait Cycle - Sequence of movements during walking, from heel strike to the next heel strike of the same foot.

• Muscle Pump - The action of muscles in aiding venous return to the heart.

Q1 (Lead - NEET PG 2012): During heel touch phase of walking, pressure in calf compartment is?

a) More than resting pressure

b) Less than resting pressure

c) No change in pressure

d) First rises and then falls

Explanation: The heel touch phase activates the gastrocnemius and soleus muscles to control foot placement and initiate push-off preparation. This contraction compresses the posterior compartment, briefly elevating intracompartmental pressure above resting level. The pressure rise aids venous return. Thus, the correct answer is a) More than resting pressure. Clinically, this principle explains why dynamic muscle use prevents venous stasis.

Q2: Which phase of the gait cycle involves maximum activity of the tibialis anterior muscle?

a) Heel strike

b) Toe-off

c) Mid-stance

d) Swing phase

Explanation: The tibialis anterior is most active during heel strike and swing phase, preventing foot slap and aiding dorsiflexion clearance. However, EMG studies show peak activation at a) Heel strike to control plantar flexion. Dysfunction may cause foot drop, requiring orthotic support.

Q3: In compartment syndrome, which parameter is most important for deciding fasciotomy?

a) Duration of symptoms

b) Pressure exceeding 30 mmHg

c) Presence of pain on passive stretch

d) Sensory loss

Explanation: While clinical signs are critical, the gold standard decision criterion is b) Pressure exceeding 30 mmHg or within 30 mmHg of diastolic BP. Persistent ischemia beyond 6 hours risks irreversible muscle and nerve damage.

Q4: Which muscle group forms the superficial layer of the posterior calf compartment?

a) Soleus and gastrocnemius

b) Tibialis posterior

c) Flexor hallucis longus

d) Peroneus longus

Explanation: The superficial posterior calf compartment includes gastrocnemius, soleus, and plantaris. The correct answer is a) Soleus and gastrocnemius. These muscles share the Achilles tendon and function mainly in plantar flexion.

Q5: A 45-year-old runner develops pain and swelling in the calf after prolonged exercise. Which is the most likely cause?

a) Acute arterial occlusion

b) Chronic exertional compartment syndrome

c) Deep vein thrombosis

d) Muscle strain

Explanation: Chronic exertional compartment syndrome (CECS) causes reversible intracompartmental pressure rise during activity, leading to pain and swelling. The hallmark is resolution with rest. Thus, b) Chronic exertional compartment syndrome fits the presentation better than DVT or strain.

Q6: The pressure in calf compartment is lowest during which gait phase?

a) Heel strike

b) Toe-off

c) Swing

d) Mid-stance

Explanation: During swing phase, calf muscles relax, reducing intracompartmental pressure below resting levels. This recovery allows reperfusion of muscles. Correct answer: c) Swing.

Q7: The primary artery supplying the posterior calf compartment is?

a) Anterior tibial artery

b) Fibular artery

c) Posterior tibial artery

d) Popliteal artery

Explanation: The posterior tibial artery supplies most of the posterior compartment, branching into medial and lateral plantar arteries in the foot. Hence, answer: c) Posterior tibial artery.

Q8: Which condition results from unrelieved acute compartment syndrome?

a) Volkmann's ischemic contracture

b) Sudeck’s atrophy

c) Osgood-Schlatter disease

d) Shin splints

Explanation: Prolonged compartment syndrome leads to ischemic necrosis and fibrosis of muscles, resulting in permanent flexion deformity known as Volkmann's ischemic contracture. Timely fasciotomy prevents this outcome.

Q9: Which nerve is most at risk in posterior calf compartment syndrome?

a) Tibial nerve

b) Superficial peroneal nerve

c) Deep peroneal nerve

d) Sural nerve

Explanation: The tibial nerve passes through the posterior compartment with posterior tibial vessels, making it most susceptible to compression in elevated pressures. Hence, a) Tibial nerve is correct.

Q10: A patient with calf pain has resting compartment pressure of 12 mmHg and post-exercise pressure of 40 mmHg. Diagnosis?

a) Acute compartment syndrome

b) Chronic exertional compartment syndrome

c) DVT

d) Muscle tear

Explanation: Resting pressure <15 mmHg is normal, but post-exercise >30-35 mmHg confirms CECS. The pattern here matches b) Chronic exertional compartment syndrome.

Q11: Which maneuver increases venous return from the calf during walking?

a) Plantar flexion

b) Dorsiflexion

c) Both plantar and dorsiflexion

d) None

Explanation: The calf muscle pump works during both plantar flexion (push-off) and dorsiflexion (relaxation), propelling blood towards the heart and preventing stasis. Correct: c) Both plantar and dorsiflexion.

Chapter: Anatomy

Topic: Upper Limb

Subtopic: Muscles of Shoulder and Arm

Keyword Definitions:

• Intertubercular sulcus: Groove between the greater and lesser tubercles of the humerus, lodging the tendon of the long head of biceps brachii.

• Latissimus dorsi: Large back muscle inserting into the floor of intertubercular sulcus, responsible for adduction, extension, and medial rotation of the arm.

• Teres major: Muscle of scapular region inserting into medial lip of intertubercular sulcus.

• Pectoralis major: Large anterior chest muscle inserting into lateral lip of intertubercular sulcus.

• Deltoid: Shoulder muscle inserting into deltoid tuberosity of humerus.

• Medial rotation: Movement turning the anterior surface of limb towards the midline.

• Adduction: Movement of limb towards the midline.

• Extension (shoulder): Movement of arm backwards in sagittal plane.

• Axillary nerve: Nerve supplying deltoid and teres minor muscles.

• Thoracodorsal nerve: Nerve supplying latissimus dorsi.

Lead Question - 2012:

Which muscle is inserted into the floor of the intertubercular sulcus of the humerus?

a) Latissimus dorsi

b) Teres major

c) Pectoralis major

d) Deltoid

The correct answer is a) Latissimus dorsi. This large muscle arises from the lower thoracic vertebrae, lumbar fascia, iliac crest, and lower ribs. It passes superiorly and laterally to insert into the floor of the intertubercular sulcus of the humerus. Its insertion site allows it to act as a powerful adductor, extensor, and medial rotator of the arm.

1. The medial lip of the intertubercular sulcus gives insertion to:
a) Teres major
b) Latissimus dorsi
c) Pectoralis major
d) Subscapularis

Answer: Teres major. This muscle assists in medial rotation and adduction of the humerus. Its medial lip insertion is an important anatomical relationship in shoulder surgery.

2. The lateral lip of the intertubercular sulcus is the insertion site for:
a) Latissimus dorsi
b) Pectoralis major
c) Teres major
d) Deltoid

Answer: Pectoralis major. This muscle flexes, adducts, and medially rotates the humerus. Its lateral lip insertion is important in differentiating from latissimus and teres major attachments.

3. Clinical: Injury to the thoracodorsal nerve will impair:
a) Lateral rotation of arm
b) Abduction of arm
c) Adduction and extension of arm
d) Flexion of forearm

Answer: Adduction and extension of arm. The thoracodorsal nerve innervates latissimus dorsi, essential for swimming and climbing movements.

4. Which muscle originates from the iliac crest and inserts into humerus?
a) Latissimus dorsi
b) Teres major
c) Deltoid
d) Pectoralis minor

Answer: Latissimus dorsi. Its broad origin includes the iliac crest, lumbar fascia, and lower thoracic spinous processes.

5. The intertubercular sulcus lodges the tendon of:
a) Long head of triceps
b) Short head of biceps
c) Long head of biceps
d) Brachialis

Answer: Long head of biceps. This tendon passes within the sulcus, stabilized by the transverse humeral ligament.

6. Clinical: During axillary lymph node dissection, damage to which nerve can cause difficulty climbing?
a) Thoracodorsal nerve
b) Axillary nerve
c) Long thoracic nerve
d) Radial nerve

Answer: Thoracodorsal nerve. It lies near axillary lymph nodes and damage impairs latissimus dorsi function.

7. Which movement will be most affected if latissimus dorsi is paralyzed?
a) Shoulder flexion
b) Shoulder extension
c) Elbow extension
d) Wrist flexion

Answer: Shoulder extension. Latissimus dorsi extends the humerus, essential in rowing and pulling actions.

8. The nerve supply of teres major is:
a) Axillary nerve
b) Lower subscapular nerve
c) Thoracodorsal nerve
d) Radial nerve

Answer: Lower subscapular nerve. This innervates teres major, contributing to adduction and medial rotation.