Chapter: Nervous System; Topic: Brachial Plexus Injuries; Subtopic: Erb’s Palsy – Nerve Root Lesions and Upper Limb Deformities
Keyword Definitions:
• Erb’s Palsy: A paralysis caused by injury to the upper trunk (C5–C6) of the brachial plexus, often during difficult childbirth or trauma.
• Brachial Plexus: A network of nerves formed by ventral rami of C5–T1 spinal nerves supplying the upper limb.
• Waiter’s Tip Posture: Typical deformity of Erb’s palsy involving arm adduction, internal rotation, and forearm pronation.
• Nerve Roots: Spinal nerve origins where sensory and motor fibers emerge from the spinal cord.
Lead Question - 2015
Upper limb deformity in Erb's palsy?
a) Adduction and lateral rotation of arm
b) Adduction and medial rotation of arm
c) Abduction and lateral rotation of arm
d) Abduction and medial rotation of arm
Explanation: The correct answer is (b) Adduction and medial rotation of arm. Erb’s palsy results from injury to the upper trunk (C5–C6) affecting suprascapular, musculocutaneous, and axillary nerves. The patient shows “waiter’s tip” posture—arm adducted and medially rotated, elbow extended, forearm pronated. It occurs due to loss of abduction, external rotation, and flexion caused by paralysis of deltoid, biceps, and supraspinatus muscles.
1) Which nerve roots are primarily affected in Erb’s palsy?
a) C3–C4
b) C5–C6
c) C7–C8
d) T1–T2
Explanation: The correct answer is (b) C5–C6. Erb’s palsy occurs due to injury at Erb’s point involving upper trunk (C5–C6). Muscles supplied by these roots—deltoid, biceps, brachialis, and supraspinatus—are paralyzed, resulting in arm adduction, internal rotation, and loss of elbow flexion. Sensory loss occurs over the lateral aspect of the arm.
2) (Clinical) A newborn presents with an internally rotated arm and inability to flex the elbow after a difficult delivery. The diagnosis is:
a) Klumpke’s palsy
b) Erb’s palsy
c) Radial nerve injury
d) Musculocutaneous nerve palsy
Explanation: The correct answer is (b) Erb’s palsy. During shoulder dystocia or breech delivery, traction on the neck can stretch or tear C5–C6 roots, leading to Erb’s palsy. The “waiter’s tip” deformity is pathognomonic, characterized by arm adduction, internal rotation, and pronated forearm. Early physiotherapy prevents contractures and improves recovery.
3) Which of the following muscles is NOT affected in Erb’s palsy?
a) Deltoid
b) Biceps
c) Brachioradialis
d) Trapezius
Explanation: The correct answer is (d) Trapezius. Trapezius is supplied by the spinal accessory nerve (cranial nerve XI) and remains intact in Erb’s palsy. In contrast, muscles innervated by C5–C6 roots—deltoid, biceps, brachialis, and supraspinatus—are affected, leading to loss of shoulder abduction and elbow flexion with characteristic “waiter’s tip” posture.
4) (Clinical) A 5-year-old boy presents with inability to abduct his shoulder and flex the elbow after a fall on the shoulder. The most likely lesion is:
a) Radial nerve injury
b) Erb’s palsy
c) Klumpke’s palsy
d) Ulnar nerve injury
Explanation: The correct answer is (b) Erb’s palsy. Traction or blow to the shoulder can stretch the upper trunk of the brachial plexus. Weakness in deltoid and biceps results in loss of abduction and elbow flexion. The limb hangs in internal rotation and pronation—classically seen as “waiter’s tip” deformity of Erb’s palsy.
5) Which of the following nerves is not derived from the C5–C6 roots?
a) Suprascapular nerve
b) Musculocutaneous nerve
c) Axillary nerve
d) Ulnar nerve
Explanation: The correct answer is (d) Ulnar nerve. The ulnar nerve originates from the C8–T1 roots, supplying the intrinsic hand muscles. C5–C6 roots give rise to nerves like suprascapular, musculocutaneous, and axillary, all of which are affected in Erb’s palsy, causing weakness in shoulder and elbow movements.
6) (Clinical) In Erb’s palsy, which movement of the upper limb is preserved?
a) Shoulder abduction
b) Elbow flexion
c) Wrist flexion
d) Shoulder external rotation
Explanation: The correct answer is (c) Wrist flexion. Wrist flexors are supplied by C7–C8 roots via the median and ulnar nerves, which are not affected in Erb’s palsy. Movements like shoulder abduction and elbow flexion are lost due to paralysis of deltoid and biceps, respectively, resulting in the classical deformity.
7) Sensory loss in Erb’s palsy typically involves which region?
a) Medial arm
b) Lateral arm
c) Posterior forearm
d) Medial forearm
Explanation: The correct answer is (b) Lateral arm. Sensory deficit occurs along the C5 dermatome, which covers the lateral upper arm region. This corresponds to areas supplied by the axillary and musculocutaneous nerves, both affected in upper trunk lesions of the brachial plexus seen in Erb’s palsy.
8) (Clinical) A patient with Erb’s palsy will have difficulty performing which activity?
a) Grasping small objects
b) Raising the arm to comb hair
c) Flexing fingers
d) Extending wrist
Explanation: The correct answer is (b) Raising the arm to comb hair. This action requires shoulder abduction and external rotation, functions of deltoid and supraspinatus (C5–C6). Their paralysis in Erb’s palsy prevents the patient from lifting the hand overhead, causing significant impairment in daily activities.
9) Which of the following best describes the posture of Erb’s palsy?
a) Claw hand
b) Ape thumb
c) Waiter’s tip
d) Wrist drop
Explanation: The correct answer is (c) Waiter’s tip. The “waiter’s tip” posture results from paralysis of C5–C6 muscles. The arm lies adducted and internally rotated, the elbow extended, and the forearm pronated, as if the person is waiting for a tip—classic sign of Erb’s palsy.
10) (Clinical) In an adult with Erb’s palsy, which treatment is most beneficial in early stages?
a) Immediate surgical repair
b) Immobilization of limb
c) Active and passive physiotherapy
d) Corticosteroid therapy
Explanation: The correct answer is (c) Active and passive physiotherapy. Early physiotherapy prevents muscle atrophy and joint contractures. Gentle range-of-motion exercises maintain flexibility while nerves recover. Surgical nerve grafting is reserved for severe cases with persistent deficits after 6–9 months of conservative management.
Chapter: Nervous System; Topic: Brachial Plexus Lesions; Subtopic: Erb’s Palsy – Nerve Roots and Clinical Manifestations
Keyword Definitions:
• Brachial Plexus: A network of spinal nerves from C5–T1 that supplies the upper limb.
• Erb’s Point: Junction of C5–C6 roots where upper trunk of the brachial plexus is formed.
• Erb’s Palsy: Paralysis caused by injury to the upper trunk (C5–C6) resulting in the “waiter’s tip” deformity.
• Waiter’s Tip Posture: The arm hangs adducted, internally rotated, with the forearm extended and pronated due to muscle paralysis.
Lead Question - 2015
Nerve roots involved in Erb's palsy:
a) C5, C6
b) C6, C7
c) C7, C8, T1
d) C5, C6, C7, C8, T1
Explanation: The correct answer is (a) C5, C6. Erb’s palsy results from injury to the upper trunk of the brachial plexus formed by the C5 and C6 nerve roots. This affects muscles like deltoid, biceps, brachialis, and supraspinatus. The characteristic deformity is “waiter’s tip” posture, with the arm adducted, internally rotated, elbow extended, and forearm pronated. Common causes include shoulder dystocia during childbirth or trauma.
1) Which part of the brachial plexus is affected in Erb’s palsy?
a) Upper trunk
b) Middle trunk
c) Lower trunk
d) Posterior cord
Explanation: The correct answer is (a) Upper trunk. Erb’s palsy involves the upper trunk (C5–C6 roots) of the brachial plexus. This lesion causes paralysis of shoulder abductors and elbow flexors leading to the “waiter’s tip” deformity. Middle and lower trunks involve different nerve root levels and cause different clinical presentations such as Klumpke’s palsy.
2) (Clinical) A newborn with shoulder dystocia presents with inability to flex the elbow and arm adduction. The most likely diagnosis is:
a) Klumpke’s palsy
b) Erb’s palsy
c) Radial nerve injury
d) Median nerve injury
Explanation: The correct answer is (b) Erb’s palsy. In difficult labor, traction on the infant’s neck stretches the C5–C6 roots. This results in paralysis of the deltoid, biceps, and supraspinatus muscles. The arm remains adducted, internally rotated, and the elbow extended. Early physiotherapy helps in preventing contractures and promoting recovery.
3) Which of the following muscles is paralyzed in Erb’s palsy?
a) Deltoid
b) Trapezius
c) Latissimus dorsi
d) Pectoralis minor
Explanation: The correct answer is (a) Deltoid. The deltoid, supplied by the axillary nerve (C5–C6), is affected in Erb’s palsy. Its paralysis results in loss of shoulder abduction. Trapezius is supplied by the spinal accessory nerve and remains unaffected. Other affected muscles include supraspinatus, biceps brachii, and brachialis.
4) (Clinical) A 25-year-old biker sustains trauma to the neck and shoulder. He presents with an adducted, internally rotated arm and extended elbow. Diagnosis is:
a) Klumpke’s palsy
b) Erb’s palsy
c) Radial nerve palsy
d) Axillary nerve lesion
Explanation: The correct answer is (b) Erb’s palsy. Traction injury to the upper trunk of the brachial plexus (C5–C6) leads to Erb’s palsy. The posture described is classical—“waiter’s tip.” The patient cannot abduct the shoulder or flex the elbow. Motor and sensory loss correspond to the C5–C6 dermatomes.
5) The “waiter’s tip” posture in Erb’s palsy is due to paralysis of which muscles?
a) Deltoid, Biceps, Brachialis, Supraspinatus
b) Triceps, Anconeus, Extensor carpi radialis
c) Flexor carpi ulnaris, Palmaris longus
d) Pectoralis minor, Subscapularis
Explanation: The correct answer is (a) Deltoid, Biceps, Brachialis, Supraspinatus. These muscles are supplied by C5–C6 roots, which are injured in Erb’s palsy. Their paralysis causes arm adduction, internal rotation, and extended elbow, resulting in the “waiter’s tip” deformity.
6) (Clinical) Which nerve is responsible for loss of shoulder abduction in Erb’s palsy?
a) Axillary nerve
b) Radial nerve
c) Median nerve
d) Ulnar nerve
Explanation: The correct answer is (a) Axillary nerve. The axillary nerve arises from the posterior cord (C5–C6) and supplies the deltoid and teres minor muscles. Damage to the C5–C6 roots causes deltoid paralysis, leading to loss of shoulder abduction in Erb’s palsy.
7) In Erb’s palsy, which movement remains intact?
a) Shoulder abduction
b) Elbow flexion
c) Wrist flexion
d) Forearm supination
Explanation: The correct answer is (c) Wrist flexion. Wrist flexors are supplied by C7–C8 via the median and ulnar nerves and are unaffected in Erb’s palsy. Shoulder abduction and elbow flexion are lost due to C5–C6 root injury, leading to a limp, pronated arm.
8) (Clinical) A child presents with inability to lift the arm overhead and flex the elbow following a fall. The most probable nerve roots affected are:
a) C3–C4
b) C5–C6
c) C7–C8
d) T1–T2
Explanation: The correct answer is (b) C5–C6. Erb’s palsy results from C5–C6 injury. These roots supply the axillary, musculocutaneous, and suprascapular nerves responsible for shoulder abduction and elbow flexion. Hence, trauma near the neck or shoulder region often causes this characteristic motor deficit.
9) Sensory loss in Erb’s palsy is observed over which area?
a) Medial forearm
b) Lateral arm
c) Posterior forearm
d) Palm
Explanation: The correct answer is (b) Lateral arm. The C5 dermatome covers the lateral upper arm supplied by the axillary and musculocutaneous nerves. Therefore, injury to C5–C6 roots results in sensory deficit over this area in Erb’s palsy, along with characteristic motor weakness.
10) (Clinical) Which of the following is an important part of Erb’s palsy rehabilitation?
a) Early physiotherapy and passive movements
b) Complete immobilization
c) Surgical nerve repair immediately
d) Use of corticosteroids
Explanation: The correct answer is (a) Early physiotherapy and passive movements. Early physiotherapy helps prevent contractures and maintain muscle tone. Gentle exercises improve the range of motion during recovery. Surgery is reserved for severe or non-recovering cases after 6–9 months of conservative treatment.
Chapter: Upper Limb Anatomy; Topic: Brachial Plexus; Subtopic: Thoracodorsal Nerve
Keyword Definitions:
• Thoracodorsal nerve: Nerve arising from the posterior cord of the brachial plexus that supplies the latissimus dorsi muscle.
• Brachial plexus: A network of nerves formed by the anterior rami of C5–T1 spinal nerves, responsible for innervating the upper limb.
• Latissimus dorsi: A broad back muscle involved in extension, adduction, and medial rotation of the arm.
Lead Question - 2015
Root value of thoracodorsal nerve?
a) C5, C6, C7
b) C8, T1
c) C6, C7, C8
d) T1, T2
Explanation:
The thoracodorsal nerve arises from the posterior cord of the brachial plexus with root values of C6, C7, and C8. It supplies the latissimus dorsi muscle, which helps in arm adduction, extension, and medial rotation. Injury to this nerve can cause weakness in pulling movements and climbing. Hence, the correct answer is c) C6, C7, C8.
1) Which nerve supplies the latissimus dorsi muscle?
a) Axillary nerve
b) Thoracodorsal nerve
c) Suprascapular nerve
d) Long thoracic nerve
Explanation:
The thoracodorsal nerve (middle subscapular nerve) supplies the latissimus dorsi muscle. This muscle extends, adducts, and medially rotates the arm. The nerve originates from the posterior cord of the brachial plexus (C6–C8). Damage affects activities like climbing or swimming that require strong shoulder adduction and extension. Answer: b) Thoracodorsal nerve.
2) The thoracodorsal nerve is a branch of:
a) Medial cord
b) Posterior cord
c) Lateral cord
d) Upper trunk
Explanation:
The thoracodorsal nerve arises from the posterior cord of the brachial plexus, along with the upper and lower subscapular nerves. It carries fibers from C6–C8 roots and supplies the latissimus dorsi. The posterior cord primarily gives nerves that innervate the posterior compartment of the upper limb. Answer: b) Posterior cord.
3) Which muscle action is lost if the thoracodorsal nerve is injured?
a) Abduction of arm
b) Extension and adduction of arm
c) Flexion of forearm
d) Supination of forearm
Explanation:
The latissimus dorsi, innervated by the thoracodorsal nerve, performs arm extension, adduction, and medial rotation. Injury to this nerve leads to weakness in these movements, especially during climbing or rowing. Abduction and supination are unaffected as they involve other muscles. The correct answer is b) Extension and adduction of arm.
4) A patient has weakness in pulling the body upward while climbing. Which nerve is likely injured?
a) Axillary nerve
b) Thoracodorsal nerve
c) Musculocutaneous nerve
d) Radial nerve
Explanation:
The thoracodorsal nerve supplies the latissimus dorsi, crucial for pulling actions like climbing or swimming. Injury causes difficulty in raising the body upward by the arms. The axillary nerve affects deltoid; musculocutaneous affects forearm flexors; radial affects wrist extensors. Hence, the answer is b) Thoracodorsal nerve.
5) The thoracodorsal nerve accompanies which artery?
a) Subscapular artery
b) Circumflex scapular artery
c) Posterior circumflex humeral artery
d) Thoracoacromial artery
Explanation:
The thoracodorsal nerve accompanies the thoracodorsal artery, a branch of the subscapular artery. Both supply the latissimus dorsi muscle. They travel together along the lateral border of the scapula towards the posterior axillary wall. This anatomical association is important during axillary dissections. Correct answer: a) Subscapular artery.
6) Clinical Case: A 35-year-old man undergoes axillary lymph node dissection for carcinoma breast. He later develops weakness in adduction of the arm. Which nerve is most likely injured?
a) Axillary nerve
b) Thoracodorsal nerve
c) Long thoracic nerve
d) Median nerve
Explanation:
During axillary dissection, the thoracodorsal nerve may be injured because it runs close to lymph nodes and vessels. This causes weakness in adduction and extension of the arm due to paralysis of the latissimus dorsi. The long thoracic nerve causes winged scapula. Correct answer: b) Thoracodorsal nerve.
7) In brachial plexus anatomy, thoracodorsal nerve lies between:
a) Upper and lower subscapular nerves
b) Medial and lateral pectoral nerves
c) Suprascapular and axillary nerves
d) Radial and musculocutaneous nerves
Explanation:
The thoracodorsal nerve lies between the upper and lower subscapular nerves, arising from the posterior cord. These three nerves innervate posterior axillary wall muscles—subscapularis and latissimus dorsi. Their anatomical proximity is vital in axillary surgery to avoid injury. Correct answer: a) Upper and lower subscapular nerves.
8) Clinical Case: A surgeon performing mastectomy notes a nerve running with subscapular vessels to the latissimus dorsi. Preserving this nerve is crucial because:
a) It controls shoulder abduction
b) It supplies latissimus dorsi
c) It supplies serratus anterior
d) It controls biceps brachii
Explanation:
The nerve described is the thoracodorsal nerve, which accompanies the subscapular vessels to supply the latissimus dorsi. Preservation is essential to maintain arm adduction and extension during shoulder movement, vital for postoperative limb function. Hence, the answer is b) It supplies latissimus dorsi.
9) Injury to the thoracodorsal nerve leads to weakness in:
a) Abduction and lateral rotation
b) Extension and medial rotation
c) Flexion and supination
d) Pronation and adduction
Explanation:
The latissimus dorsi muscle, innervated by the thoracodorsal nerve, is primarily responsible for arm extension, adduction, and medial rotation. Damage results in weakness of these movements, especially while performing activities requiring strong shoulder depression and pulling. The correct answer is b) Extension and medial rotation.
10) Which root value combination is incorrect for the thoracodorsal nerve?
a) C6
b) C7
c) C8
d) T1
Explanation:
The thoracodorsal nerve arises from the posterior cord of the brachial plexus, with root values from C6, C7, and C8. It has no contribution from T1. The incorrect option is d) T1. Understanding root values is vital for correlating nerve injuries with muscle weakness patterns.
Chapter: Upper Limb Anatomy; Topic: Shoulder Muscles; Subtopic: Teres Minor and Its Nerve Supply
Keyword Definitions:
• Teres minor: A small rotator cuff muscle located on the posterior aspect of the scapula that assists in lateral rotation of the arm.
• Axillary nerve: A branch of the posterior cord of the brachial plexus (C5–C6) that supplies the deltoid and teres minor muscles.
• Rotator cuff: A group of four muscles (supraspinatus, infraspinatus, teres minor, subscapularis) that stabilize the shoulder joint.
Lead Question - 2015
Teres minor is supplied by:
a) Suprascapular nerve
b) Infrascapular nerve
c) Thoracodorsal nerve
d) Axillary nerve
Explanation:
The teres minor muscle is supplied by the axillary nerve (C5, C6) from the posterior cord of the brachial plexus. This muscle assists in the lateral rotation of the arm and stabilizes the humeral head in the glenoid cavity. Injury to the axillary nerve can weaken abduction and lateral rotation. Hence, the correct answer is d) Axillary nerve.
1) The teres minor muscle is part of which muscle group?
a) Rotator cuff muscles
b) Pectoral muscles
c) Axial muscles
d) Scapular stabilizers
Explanation:
The teres minor belongs to the rotator cuff group along with supraspinatus, infraspinatus, and subscapularis. These muscles surround the shoulder joint, providing stability and allowing precise rotational movements. The teres minor specifically aids in lateral rotation and prevents humeral head dislocation. Correct answer: a) Rotator cuff muscles.
2) Which nerve supplies both deltoid and teres minor muscles?
a) Radial nerve
b) Axillary nerve
c) Musculocutaneous nerve
d) Suprascapular nerve
Explanation:
The axillary nerve innervates both the deltoid and teres minor muscles. It originates from the posterior cord of the brachial plexus (C5, C6). The nerve also gives rise to the superior lateral cutaneous nerve of the arm, providing sensation to the deltoid region. Answer: b) Axillary nerve.
3) Which of the following actions is performed by the teres minor?
a) Medial rotation
b) Lateral rotation
c) Flexion of the arm
d) Abduction of the arm
Explanation:
The teres minor functions mainly in lateral rotation of the arm at the shoulder joint. It acts synergistically with the infraspinatus muscle to stabilize the humeral head during movement. This helps in controlled shoulder motion and joint protection. The correct answer is b) Lateral rotation.
4) Clinical Case: A patient presents with difficulty in abducting the arm beyond 15° and weakness in lateral rotation. Which nerve is injured?
a) Axillary nerve
b) Radial nerve
c) Suprascapular nerve
d) Long thoracic nerve
Explanation:
Loss of abduction beyond 15° (deltoid) and weakness in lateral rotation (teres minor) suggest an axillary nerve injury. This nerve supplies both muscles and is vulnerable during shoulder dislocation or surgical neck fracture of the humerus. Correct answer: a) Axillary nerve.
5) The axillary nerve passes through which anatomical space?
a) Triangular interval
b) Quadrangular space
c) Triangular space
d) Subscapular space
Explanation:
The axillary nerve travels through the quadrangular space along with the posterior circumflex humeral artery. The boundaries are teres minor (superior), teres major (inferior), long head of triceps (medial), and surgical neck of humerus (lateral). Injury here may cause deltoid paralysis. Answer: b) Quadrangular space.
6) Clinical Case: During shoulder surgery, a small branch near the posterior circumflex humeral artery is injured. The patient later develops weakness in lateral rotation. Which muscle is affected?
a) Subscapularis
b) Teres major
c) Teres minor
d) Infraspinatus
Explanation:
The teres minor receives its branch from the axillary nerve in the quadrangular space near the posterior circumflex humeral artery. Injury to this branch results in weakness in lateral rotation. Teres major is supplied by the lower subscapular nerve. Correct answer: c) Teres minor.
7) Which muscle is NOT part of the rotator cuff?
a) Teres minor
b) Supraspinatus
c) Infraspinatus
d) Teres major
Explanation:
The rotator cuff includes supraspinatus, infraspinatus, teres minor, and subscapularis. The teres major is not part of the cuff; it adducts and medially rotates the arm and is supplied by the lower subscapular nerve. Hence, the correct answer is d) Teres major.
8) Clinical Case: A patient with posterior shoulder dislocation develops weakness in abduction and lateral rotation. Which nerve is involved?
a) Radial nerve
b) Axillary nerve
c) Suprascapular nerve
d) Musculocutaneous nerve
Explanation:
The axillary nerve is injured in posterior shoulder dislocation due to its close relation to the humeral neck. It causes paralysis of the deltoid and teres minor, leading to loss of abduction and lateral rotation. Correct answer: b) Axillary nerve.
9) Which artery accompanies the axillary nerve in the quadrangular space?
a) Subscapular artery
b) Posterior circumflex humeral artery
c) Anterior circumflex humeral artery
d) Thoracodorsal artery
Explanation:
The posterior circumflex humeral artery accompanies the axillary nerve through the quadrangular space. This vessel arises from the third part of the axillary artery and supplies the deltoid and teres minor. Injury may cause hemorrhage and nerve damage. Correct answer: b) Posterior circumflex humeral artery.
10) Damage to the axillary nerve affects which sensory area?
a) Lateral arm
b) Medial forearm
c) Posterior forearm
d) Medial arm
Explanation:
The axillary nerve gives rise to the superior lateral cutaneous nerve of the arm, supplying the skin over the deltoid (regimental badge area). Damage causes numbness or paresthesia here. This finding helps in clinical diagnosis of axillary nerve injury. Correct answer: a) Lateral arm.
Chapter: Upper Limb Anatomy; Topic: Scapular Muscles; Subtopic: Levator Scapulae Muscle
Keyword Definitions:
Levator Scapulae: A muscle originating from the transverse processes of C1–C4 vertebrae that elevates the scapula.
Scapula: A flat triangular bone connecting the humerus with the clavicle, forming the shoulder blade.
Insertion: The point where a muscle attaches to a bone, usually the movable part during contraction.
Medial Border: The edge of the scapula nearest the vertebral column.
Lead Question – 2015
Insertion of levator scapulae is ?
a) Lateral border of scapula
b) Supralateral part of scapula
c) Superior part of medial scapula border
d) Inferior angle of scapula
Explanation: Levator scapulae inserts into the superior part of the medial border of the scapula, between the superior angle and the root of the spine of scapula. It acts to elevate the scapula and assist in downward rotation. The muscle is innervated by the dorsal scapular nerve (C5) and cervical nerves (C3, C4).
1. Which nerve supplies the levator scapulae muscle?
a) Long thoracic nerve
b) Dorsal scapular nerve
c) Axillary nerve
d) Spinal accessory nerve
Explanation: Levator scapulae is primarily supplied by the dorsal scapular nerve (C5) and cervical nerves (C3, C4). This innervation enables elevation and rotation of the scapula during shoulder movements. Injury to this nerve weakens scapular elevation, but trapezius partially compensates due to its similar action.
2. Which of the following muscles attaches to the superior angle of the scapula?
a) Rhomboid major
b) Rhomboid minor
c) Levator scapulae
d) Serratus anterior
Explanation: Levator scapulae inserts at the superior angle and upper medial border of the scapula, elevating it and assisting in rotation. Rhomboids attach to the medial border below this point. Serratus anterior inserts along the anterior surface of the medial border.
3. Clinical sign of dorsal scapular nerve injury includes:
a) Winged scapula
b) Drooping of shoulder
c) Difficulty elevating scapula
d) Flattened deltoid
Explanation: Dorsal scapular nerve injury leads to weakness in levator scapulae and rhomboids, resulting in difficulty elevating and retracting the scapula. However, winged scapula occurs due to long thoracic nerve injury affecting serratus anterior, distinguishing it from this condition.
4. Levator scapulae arises from which vertebrae?
a) C1–C4 transverse processes
b) C5–C7 spinous processes
c) C2–C6 spinous processes
d) C1–C3 anterior tubercles
Explanation: The levator scapulae originates from the transverse processes of the first four cervical vertebrae (C1–C4). Its fibers descend to insert into the medial border of the scapula, elevating the bone and rotating it downward during shoulder movements.
5. In a patient with levator scapulae paralysis, which movement is most affected?
a) Shoulder abduction
b) Scapular elevation
c) Shoulder flexion
d) Arm medial rotation
Explanation: Levator scapulae is responsible for elevation and downward rotation of the scapula. Paralysis leads to difficulty in lifting the shoulder and reduced scapular stability. Other shoulder movements, like abduction and flexion, remain largely unaffected due to intact deltoid and trapezius action.
6. Which muscle acts synergistically with levator scapulae during scapular elevation?
a) Trapezius
b) Serratus anterior
c) Pectoralis minor
d) Latissimus dorsi
Explanation: The upper fibers of the trapezius muscle assist the levator scapulae in elevating the scapula. Both muscles coordinate for shrugging or lifting the shoulders. Serratus anterior acts oppositely by protracting and rotating the scapula upward.
7. Which artery accompanies the dorsal scapular nerve near the levator scapulae?
a) Subscapular artery
b) Dorsal scapular artery
c) Thoracodorsal artery
d) Transverse cervical artery
Explanation: The dorsal scapular artery runs alongside the dorsal scapular nerve, supplying the levator scapulae, rhomboids, and part of the trapezius. It provides vascular support to muscles stabilizing the scapula, ensuring their function during shoulder and neck movements.
8. A patient has pain along the upper neck and shoulder due to levator scapulae spasm. Which posture worsens pain?
a) Neck flexion
b) Shoulder elevation
c) Prolonged head rotation
d) Arm abduction
Explanation: Prolonged head rotation or looking down while sitting strains levator scapulae, leading to myofascial pain. This is common in people working long hours at computers. Stretching and posture correction relieve symptoms. Shoulder elevation briefly relaxes the muscle but chronic tension aggravates it.
9. Levator scapulae assists which other muscle in downward rotation of the scapula?
a) Pectoralis major
b) Rhomboid minor
c) Latissimus dorsi
d) Trapezius lower fibers
Explanation: Levator scapulae works with rhomboids to rotate the scapula downward. Both pull the medial border upward and inward. This movement is vital for returning the elevated scapula to rest after shoulder abduction. Dysfunction causes imbalance in scapular rotation and posture.
10. During neck dissection surgery, injury to the dorsal scapular nerve may affect:
a) Trapezius and sternocleidomastoid
b) Rhomboids and levator scapulae
c) Deltoid and teres minor
d) Serratus anterior and pectoralis minor
Explanation: Dorsal scapular nerve injury during neck dissection weakens levator scapulae and rhomboids, leading to scapular droop and impaired retraction. Trapezius remains intact as it is supplied by the spinal accessory nerve, differentiating the pattern of muscle weakness clinically.
11. Levator scapulae stabilizes the scapula during which movement?
a) Climbing
b) Throwing
c) Lifting heavy weight
d) Writing
Explanation: During climbing or lifting, levator scapulae stabilizes and elevates the scapula, preventing downward displacement. It maintains scapular position, allowing efficient upper limb force transmission. Dysfunction reduces lifting power and neck stability, emphasizing its postural importance in upper limb mechanics.
Chapter: Anatomy of the Breast; Topic: Mammary Gland; Subtopic: Lobes and Duct System
Keyword Definitions:
Breast: A modified sweat gland located in the pectoral region that functions in milk secretion in females.
Lobes: Distinct glandular units of the breast, each draining through a separate lactiferous duct.
Lactiferous Ducts: Tubes that carry milk from the lobes to the nipple.
Areola: Pigmented area surrounding the nipple containing sebaceous glands.
Lead Question – 2015
Number of lobes in breast
a) 5
b) 10
c) 15
d) 30
Explanation: The breast typically has 15 to 20 lobes, each made up of numerous lobules that contain alveoli for milk secretion. Each lobe opens through a separate lactiferous duct onto the nipple. The number may vary slightly between individuals but functionally averages around 15–20. Answer: (c) 15.
1. The functional unit of the breast is:
a) Lobe
b) Lobule
c) Alveolus
d) Lactiferous duct
Explanation: The alveolus is the functional unit of the breast, responsible for milk synthesis and secretion under the influence of prolactin. Each lobule contains multiple alveoli that drain into intralobular ducts, which then form larger ducts converging toward the nipple. Answer: (c) Alveolus.
2. The breast lies over which muscle?
a) Serratus anterior
b) Pectoralis major
c) Latissimus dorsi
d) External oblique
Explanation: The breast rests on the deep fascia covering the pectoralis major muscle and partly on the serratus anterior. A layer of loose connective tissue called the retromammary space allows movement of the breast over the pectoral fascia. Answer: (b) Pectoralis major.
3. Which hormone primarily stimulates milk secretion?
a) Estrogen
b) Progesterone
c) Prolactin
d) Oxytocin
Explanation: Prolactin, secreted by the anterior pituitary gland, promotes milk secretion from alveolar epithelial cells. Estrogen and progesterone prepare the gland for lactation but inhibit secretion until after delivery when their levels drop. Answer: (c) Prolactin.
4. Which structure drains milk from each breast lobe to the nipple?
a) Alveolar duct
b) Intralobular duct
c) Lactiferous duct
d) Areolar gland
Explanation: Each breast lobe is drained by a lactiferous duct, which widens into a lactiferous sinus beneath the areola before opening at the nipple. This duct system ensures milk delivery during lactation. Answer: (c) Lactiferous duct.
5. Which ligament supports the breast structure?
a) Cooper’s ligament
b) Suspensory ligament of ovary
c) Round ligament
d) Pectoral ligament
Explanation: Cooper’s ligaments (suspensory ligaments) are fibrous connective tissue bands that anchor the breast to the pectoral fascia and skin, maintaining shape. Their contraction during carcinoma causes skin dimpling. Answer: (a) Cooper’s ligament.
6. Clinical: A woman presents with nipple retraction. Which structure is likely involved?
a) Lactiferous ducts
b) Cooper’s ligaments
c) Retromammary space
d) Areolar glands
Explanation: Retraction of the nipple often results from fibrosis or malignancy involving the lactiferous ducts. The fibrosis pulls the ducts inward, causing visible retraction. It is a significant sign of breast carcinoma. Answer: (a) Lactiferous ducts.
7. Lymph from the lateral quadrant of the breast mainly drains into:
a) Parasternal nodes
b) Axillary nodes
c) Infraclavicular nodes
d) Supraclavicular nodes
Explanation: Approximately 75% of breast lymph drains into axillary lymph nodes, especially the anterior (pectoral) group. The medial quadrants drain into parasternal nodes. Understanding lymphatic drainage is crucial in assessing metastasis. Answer: (b) Axillary nodes.
8. During radical mastectomy, which nerve should be preserved to avoid scapular winging?
a) Long thoracic nerve
b) Thoracodorsal nerve
c) Intercostobrachial nerve
d) Suprascapular nerve
Explanation: The long thoracic nerve supplies the serratus anterior. Injury leads to scapular winging due to paralysis of the muscle, preventing the scapula from adhering to the thoracic wall. Answer: (a) Long thoracic nerve.
9. Clinical: A lactating mother presents with a painful lump and fever. Likely diagnosis is:
a) Fibroadenoma
b) Mastitis
c) Carcinoma
d) Lipoma
Explanation: Mastitis is an inflammatory condition of the breast, often due to Staphylococcus aureus infection during lactation. It causes localized pain, redness, and fever. Proper hygiene and drainage are vital for management. Answer: (b) Mastitis.
10. Which quadrant of the breast is most prone to carcinoma?
a) Upper outer
b) Lower outer
c) Upper inner
d) Lower inner
Explanation: The upper outer quadrant of the breast is the most frequent site of carcinoma because it contains the highest proportion of glandular tissue and lymphatic drainage toward the axilla, facilitating metastasis. Answer: (a) Upper outer.
11. Clinical: In carcinoma of the breast, peau d’orange appearance occurs due to:
a) Blocked sebaceous glands
b) Lymphatic obstruction
c) Fat necrosis
d) Cooper’s ligament hypertrophy
Explanation: Peau d’orange (orange peel) appearance in breast carcinoma is due to lymphatic obstruction causing edema of the skin. The tethering of skin by Cooper’s ligaments exaggerates the dimpling effect, giving the surface an orange-like texture. Answer: (b) Lymphatic obstruction.
Chapter: Upper Limb Anatomy;Topic: Muscles of the Arm; Subtopic: Origin and Insertion of Muscles around Scapula
Keyword Definitions:
Infraglenoid Tubercle: A small prominence located below the glenoid cavity of the scapula, serving as the point of origin for the long head of the triceps brachii muscle.
Triceps Brachii: A large muscle at the back of the upper arm with three heads (long, lateral, and medial) responsible for forearm extension at the elbow.
Biceps Brachii: A two-headed muscle on the anterior aspect of the arm involved in flexion and supination of the forearm.
Scapula: The flat triangular bone of the shoulder that provides attachment sites for multiple muscles.
Lead Question – 2015
Which of the following arises from infraglenoid tubercle –
a) Long head of biceps
b) Long head of triceps
c) Short head of biceps
d) Coracobrachialis
Explanation: The long head of the triceps brachii originates from the infraglenoid tubercle of the scapula. It descends between the teres minor and teres major, joining other heads to form a common tendon inserting into the olecranon process of the ulna. It extends the elbow and aids shoulder extension. Answer: (b) Long head of triceps.
1. The long head of biceps arises from:
a) Supraglenoid tubercle
b) Infraglenoid tubercle
c) Coracoid process
d) Glenoid cavity
Explanation: The long head of the biceps brachii originates from the supraglenoid tubercle of the scapula. Its tendon passes through the shoulder joint cavity and the intertubercular groove of the humerus, stabilized by the transverse humeral ligament. Answer: (a) Supraglenoid tubercle.
2. The short head of the biceps brachii arises from:
a) Coracoid process
b) Acromion
c) Clavicle
d) Scapular spine
Explanation: The short head of the biceps brachii originates from the tip of the coracoid process along with the coracobrachialis. It joins the long head to insert into the radial tuberosity, enabling flexion of the elbow and supination of the forearm. Answer: (a) Coracoid process.
3. Which muscle of the arm is supplied by the radial nerve?
a) Triceps brachii
b) Biceps brachii
c) Coracobrachialis
d) Brachialis
Explanation: The radial nerve supplies the triceps brachii, anconeus, and posterior compartment muscles of the arm and forearm. It facilitates elbow extension and wrist movement. Damage results in wrist drop due to paralysis of extensors. Answer: (a) Triceps brachii.
4. Clinical: A patient with posterior cord injury presents with inability to extend the elbow. Which nerve is affected?
a) Musculocutaneous nerve
b) Radial nerve
c) Axillary nerve
d) Median nerve
Explanation: The radial nerve, derived from the posterior cord of the brachial plexus, innervates the triceps brachii. Injury leads to loss of elbow extension and wrist drop. Sensory loss occurs over the posterior arm and forearm. Answer: (b) Radial nerve.
5. Which of the following muscles extends the forearm at the elbow joint?
a) Biceps brachii
b) Brachialis
c) Triceps brachii
d) Coracobrachialis
Explanation: The triceps brachii, particularly its long and lateral heads, are the primary extensors of the elbow joint. The medial head provides sustained contraction during extension. The triceps also aids shoulder extension. Answer: (c) Triceps brachii.
6. Clinical: A person receives a penetrating injury near the spiral groove. Which movement is most affected?
a) Shoulder flexion
b) Elbow extension
c) Wrist extension
d) Elbow flexion
Explanation: Radial nerve injury in the spiral groove spares the long head of triceps but paralyzes extensors of the wrist and fingers, resulting in wrist drop. Shoulder and elbow functions are relatively preserved. Answer: (c) Wrist extension.
7. Which head of the triceps is the deepest?
a) Long head
b) Lateral head
c) Medial head
d) None of the above
Explanation: The medial head of the triceps is the deepest and lies beneath the other two heads. It originates from the posterior surface of the humerus below the radial groove and provides stability during prolonged contraction. Answer: (c) Medial head.
8. Which artery supplies the triceps brachii?
a) Brachial artery
b) Deep brachial artery
c) Axillary artery
d) Subclavian artery
Explanation: The deep brachial artery (profunda brachii), a branch of the brachial artery, supplies the triceps brachii. It accompanies the radial nerve in the spiral groove and provides collateral circulation around the elbow. Answer: (b) Deep brachial artery.
9. Clinical: A patient is unable to adduct and extend the shoulder after injury to the axilla. Which muscle is likely involved?
a) Teres minor
b) Triceps long head
c) Biceps short head
d) Supraspinatus
Explanation: The long head of the triceps brachii assists in shoulder adduction and extension. Damage to the infraglenoid region or radial nerve impairs these movements. Answer: (b) Triceps long head.
10. The triceps tendon inserts into which bony landmark?
a) Olecranon process
b) Coronoid process
c) Radial tuberosity
d) Ulnar tuberosity
Explanation: All three heads of the triceps brachii converge to insert on the olecranon process of the ulna. This insertion allows efficient extension at the elbow joint during pushing or throwing actions. Answer: (a) Olecranon process.
Chapter: Upper Limb Anatomy; Topic: Muscles of Scapula; Subtopic: Attachments on Medial Border of Scapula
Keyword Definitions:
• Scapula: Flat triangular bone forming the posterior part of the shoulder girdle.
• Medial Border: The edge of the scapula closest to the vertebral column, serving as an attachment for several muscles.
• Serratus Anterior: Muscle aiding in protraction of the scapula.
• Levator Scapulae: Elevates the scapula.
• Rhomboid Major: Retracts and stabilizes the scapula.
• Teres Major: A muscle attached to the inferior angle and lateral border of the scapula, not the medial border.
Lead Question – 2015
Not attached on medial border of scapula?
a) Serratus anterior
b) Levator scapulae
c) Rhomboideus major
d) Teres major
Explanation: The Teres major muscle arises from the dorsal surface of the inferior angle and the lower part of the lateral border of the scapula, not the medial border. The medial border gives attachment to the levator scapulae, rhomboid major, rhomboid minor, and serratus anterior. Hence, the correct answer is d) Teres major.
Guessed Questions:
1. Which muscle inserts into the medial border of the scapula?
a) Teres major
b) Rhomboid minor
c) Latissimus dorsi
d) Deltoid
Explanation: The Rhomboid minor inserts into the medial border of the scapula at the level of the spine. It retracts the scapula and stabilizes it. The other muscles attach to different parts of the humerus or scapula. Hence, the correct answer is b) Rhomboid minor.
2. Which nerve supplies the serratus anterior muscle?
a) Dorsal scapular nerve
b) Long thoracic nerve
c) Axillary nerve
d) Suprascapular nerve
Explanation: The Long thoracic nerve supplies the serratus anterior muscle, enabling scapular protraction and upward rotation. Damage to this nerve leads to a winged scapula. The other nerves supply different muscles of the shoulder girdle. Hence, the correct answer is b) Long thoracic nerve.
3. Paralysis of which muscle causes winging of the scapula?
a) Rhomboid major
b) Levator scapulae
c) Serratus anterior
d) Teres major
Explanation: Winging of the scapula occurs due to paralysis of the serratus anterior muscle from long thoracic nerve injury. The scapula protrudes posteriorly when pushing against resistance. This condition commonly occurs after axillary surgery or trauma. Hence, the correct answer is c) Serratus anterior.
4. Which muscle elevates the scapula?
a) Levator scapulae
b) Serratus anterior
c) Pectoralis minor
d) Teres minor
Explanation: The Levator scapulae elevates the medial border of the scapula and assists in downward rotation. It is innervated by the dorsal scapular nerve. The other muscles perform protraction or depression functions. Hence, the correct answer is a) Levator scapulae.
5. The dorsal scapular nerve supplies all except?
a) Rhomboid minor
b) Levator scapulae
c) Rhomboid major
d) Serratus anterior
Explanation: The Serratus anterior is supplied by the long thoracic nerve, not the dorsal scapular nerve. The dorsal scapular nerve innervates the rhomboid major, rhomboid minor, and levator scapulae muscles. Hence, the correct answer is d) Serratus anterior.
6. A patient with a fractured inferior angle of the scapula may have difficulty in?
a) Arm elevation
b) Scapular protraction
c) Scapular depression
d) Arm abduction beyond 90°
Explanation: The Teres major originates from the inferior angle of the scapula, and its function includes medial rotation and adduction of the arm. Fracture at this site limits these actions. Therefore, arm adduction and medial rotation are primarily affected. Hence, the correct answer is a) Arm elevation.
7. The scapular notch transmits which structure?
a) Suprascapular artery
b) Suprascapular nerve
c) Axillary nerve
d) Circumflex scapular artery
Explanation: The Suprascapular nerve passes through the scapular notch beneath the superior transverse scapular ligament. The artery passes above the ligament. This region is clinically significant due to entrapment neuropathies. Hence, the correct answer is b) Suprascapular nerve.
8. Which muscle helps in downward rotation of the scapula?
a) Serratus anterior
b) Pectoralis minor
c) Trapezius (upper fibers)
d) Deltoid
Explanation: The Pectoralis minor assists in the downward rotation of the scapula by pulling the coracoid process inferiorly and medially. It also aids in scapular depression during forced inspiration. Hence, the correct answer is b) Pectoralis minor.
9. A patient presents with difficulty retracting the scapula. Which muscle is likely affected?
a) Rhomboid major
b) Levator scapulae
c) Serratus anterior
d) Pectoralis minor
Explanation: The Rhomboid major muscle retracts and stabilizes the scapula. Damage to its nerve supply (dorsal scapular nerve) leads to weakened retraction. Hence, the correct answer is a) Rhomboid major.
10. The inferior angle of the scapula is an important landmark for identifying which level?
a) T4 vertebra
b) T7 vertebra
c) T10 vertebra
d) T12 vertebra
Explanation: The Inferior angle of the scapula lies opposite the T7 vertebral spine when the arm is by the side. It serves as an important surface landmark during clinical examinations and imaging. Hence, the correct answer is b) T7 vertebra.
Chapter: Neuroanatomy; Topic: Spinal Nerve Roots; Subtopic: Cervical Nerve Root Lesions
Keyword Definitions:
• Herniated Intervertebral Disc: Protrusion of nucleus pulposus through the annulus fibrosus, compressing adjacent nerve roots.
• Cervical Nerve Roots: Nerves arising from the cervical spinal cord that control upper limb muscles.
• C5 Nerve Root: Supplies deltoid and biceps brachii muscles responsible for shoulder abduction and elbow flexion.
• Elbow Flexion: Bending the elbow joint mainly by biceps brachii and brachialis.
• Disc Herniation Symptoms: Include pain, numbness, and weakness in corresponding myotomal distribution.
Lead Question – 2015
A patient has a herniated intervertebral disc impinging on the right C5 nerve roots. Which of the following movements would most likely be affected?
a) Extension of the fingers
b) Extension of the shoulder
c) Flexion of the elbow
d) Flexion of the wrist
Explanation: The C5 nerve root primarily innervates the deltoid and biceps brachii muscles, which control shoulder abduction and elbow flexion. Herniation compressing C5 results in weakness of elbow flexion and shoulder movement, along with diminished biceps reflex. The correct answer is c) Flexion of the elbow as it represents the key function affected by C5 root involvement.
Guessed Questions:
1. Which spinal nerve root is primarily responsible for wrist extension?
a) C5
b) C6
c) C7
d) C8
Explanation: The C6 nerve root innervates muscles such as the extensor carpi radialis longus and brevis that extend the wrist. C7 mainly controls finger extension, while C8 influences finger flexion. Compression of the C6 root causes weakness in wrist extension and loss of biceps reflex. Hence, the correct answer is b) C6.
2. Which reflex is affected by C5 nerve root compression?
a) Triceps reflex
b) Biceps reflex
c) Brachioradialis reflex
d) Knee jerk reflex
Explanation: The biceps reflex is mediated by the C5 and C6 spinal roots, primarily C5. Compression of C5 impairs this reflex and weakens elbow flexion. The triceps reflex (C7–C8) and brachioradialis reflex (C6) remain intact. Hence, the correct answer is b) Biceps reflex.
3. A patient with C6 radiculopathy may have weakness in which movement?
a) Finger abduction
b) Wrist extension
c) Shoulder adduction
d) Elbow extension
Explanation: The C6 nerve root controls wrist extension via the extensor carpi radialis and contributes to elbow flexion. Compression causes weakness in wrist extension, sensory loss in the thumb, and diminished brachioradialis reflex. Hence, the correct answer is b) Wrist extension.
4. C7 nerve root lesion results in difficulty performing which action?
a) Elbow flexion
b) Elbow extension
c) Shoulder abduction
d) Wrist flexion
Explanation: The C7 root supplies the triceps brachii, responsible for elbow extension. Compression causes weakness in extending the elbow and fingers, and loss of triceps reflex. Sensory loss occurs in the middle finger region. Hence, the correct answer is b) Elbow extension.
5. Which intervertebral disc herniation most likely affects the C5 nerve root?
a) C3–C4 disc
b) C4–C5 disc
c) C5–C6 disc
d) C6–C7 disc
Explanation: In the cervical spine, the nerve root exiting above the herniated disc is usually affected. Thus, herniation at the C4–C5 disc compresses the C5 nerve root, leading to pain and weakness in the shoulder and elbow flexion. Hence, the correct answer is b) C4–C5 disc.
6. A patient presents with loss of biceps reflex and shoulder abduction. Which nerve root is most likely involved?
a) C5
b) C6
c) C7
d) C8
Explanation: The C5 root controls shoulder abduction (deltoid) and elbow flexion (biceps). Injury results in weakness in both movements and absent biceps reflex. C6–C8 control lower arm functions. Hence, the correct answer is a) C5.
7. Pain radiating over the lateral shoulder and upper arm suggests involvement of which nerve root?
a) C4
b) C5
c) C6
d) C7
Explanation: The C5 dermatome covers the lateral shoulder and upper arm. Herniation at C4–C5 compressing the C5 root causes pain, tingling, and weakness in this region. The pattern helps differentiate it from lower cervical lesions. Hence, the correct answer is b) C5.
8. A 40-year-old patient has difficulty abducting the shoulder and diminished biceps reflex. Which disc level is affected?
a) C3–C4
b) C4–C5
c) C5–C6
d) C6–C7
Explanation: The C4–C5 disc herniation compresses the C5 root, impairing deltoid and biceps function. Symptoms include shoulder abduction weakness and reduced biceps reflex. Hence, the correct answer is b) C4–C5.
9. Which muscle would show weakness in C5 root compression?
a) Deltoid
b) Triceps
c) Extensor digitorum
d) Flexor carpi ulnaris
Explanation: The Deltoid muscle, innervated by the axillary nerve (C5–C6), is primarily affected in C5 compression. The patient cannot abduct the arm efficiently. Hence, the correct answer is a) Deltoid.
10. A patient with cervical disc prolapse presents with weakness in shoulder abduction and elbow flexion, sensory loss over lateral arm, and absent biceps reflex. Which root is compressed?
a) C4
b) C5
c) C6
d) C7
Explanation: This clinical presentation is classical of C5 root compression. It affects the deltoid and biceps muscles, leading to weakness of shoulder abduction and elbow flexion, sensory loss over the lateral arm, and absent biceps reflex. Hence, the correct answer is b) C5.
Chapter: Upper Limb Anatomy; Topic: Cubital Fossa; Subtopic: Boundaries of Cubital Fossa
Keyword Definitions:
• Cubital Fossa: Triangular depression on the anterior aspect of the elbow, containing key structures like the brachial artery, median nerve, and tendon of biceps brachii.
• Medial Boundary: The inner edge of the cubital fossa, formed by muscles and connective tissue.
• Pronator Teres: A muscle of the anterior forearm that forms the medial boundary of the cubital fossa.
• Brachioradialis: Lateral border muscle of cubital fossa.
• Supinator: Muscle on the posterior-lateral aspect of forearm, not a boundary of cubital fossa.
Lead Question – 2015
Medial boundary of Cubital fossa ?
a) Brachioradialis
b) Pronator teres
c) Supinator
d) None
Explanation: The cubital fossa is bounded medially by the pronator teres muscle, laterally by the brachioradialis, and superiorly by an imaginary line connecting the epicondyles. The fossa contains the biceps tendon, brachial artery, and median nerve. Supinator does not form any boundary. Therefore, the correct answer is b) Pronator teres. Understanding the boundaries is crucial for venipuncture, arterial puncture, and surgical approaches in the antecubital region.
Guessed Questions:
1. Lateral boundary of cubital fossa is formed by?
a) Pronator teres
b) Brachioradialis
c) Supinator
d) Flexor carpi radialis
Explanation: The brachioradialis forms the lateral boundary of the cubital fossa, while the pronator teres forms the medial boundary. Superiorly, an imaginary line connects epicondyles. Knowledge of these boundaries is essential for identifying vascular and neural structures in the fossa. Hence, the correct answer is b) Brachioradialis.
2. Floor of the cubital fossa is formed by?
a) Brachialis and supinator muscles
b) Pronator teres
c) Brachioradialis
d) Biceps brachii
Explanation: The floor of the cubital fossa is formed by the brachialis medially and supinator laterally. These muscles support the overlying vascular and neural structures, important in surgical approaches. Hence, the correct answer is a) Brachialis and supinator muscles.
3. Roof of the cubital fossa consists of?
a) Bicipital aponeurosis and fascia
b) Pronator teres
c) Brachialis
d) Supinator
Explanation: The roof of the cubital fossa is formed by the bicipital aponeurosis and deep fascia, protecting underlying structures like brachial artery and median nerve. Pronator teres and brachialis form boundaries or floor. Hence, the correct answer is a) Bicipital aponeurosis and fascia.
4. Which structure passes through the cubital fossa medially?
a) Biceps tendon
b) Median nerve
c) Radial artery
d) Ulnar nerve
Explanation: The median nerve passes through the cubital fossa medially to the brachial artery. The biceps tendon lies centrally, radial artery laterally. Ulnar nerve passes posterior to the medial epicondyle, not in the fossa. Hence, the correct answer is b) Median nerve.
5. Most lateral structure in cubital fossa?
a) Biceps tendon
b) Radial nerve
c) Brachial artery
d) Median nerve
Explanation: The radial nerve lies lateral in relation to the cubital fossa structures, lying beneath brachioradialis. Biceps tendon is central, brachial artery and median nerve are medial to it. Hence, the correct answer is b) Radial nerve.
6. Which vein is commonly punctured in the cubital fossa?
a) Cephalic vein
b) Basilic vein
c) Median cubital vein
d) Radial vein
Explanation: The median cubital vein connects cephalic and basilic veins, lying superficially across the cubital fossa, making it ideal for venipuncture. Knowledge of boundaries prevents accidental arterial puncture. Hence, the correct answer is c) Median cubital vein.
7. Which structure forms the apex of cubital fossa?
a) Biceps tendon
b) Junction of brachioradialis and pronator teres
c) Medial epicondyle
d) Lateral epicondyle
Explanation: The apex of the cubital fossa is formed where the brachioradialis and pronator teres meet, converging inferiorly. This marks the transition to the forearm. Hence, the correct answer is b) Junction of brachioradialis and pronator teres.
8. Which artery is present in the cubital fossa?
a) Brachial artery
b) Radial artery
c) Ulnar artery
d) Axillary artery
Explanation: The brachial artery passes centrally through the cubital fossa, dividing into radial and ulnar arteries at the level of the neck of the radius. It lies medial to the biceps tendon and lateral to the median nerve. Hence, the correct answer is a) Brachial artery.
9. Clinical importance of cubital fossa includes all EXCEPT?
a) Venipuncture
b) Arterial blood sampling
c) Nerve blocks
d) Hip joint injection
Explanation: The cubital fossa is clinically important for venipuncture, arterial blood sampling, and nerve blocks due to superficial vessels and nerves. Hip joint injection is unrelated. Hence, the correct answer is d) Hip joint injection.
10. Compression of median nerve in cubital fossa results in?
a) Weak elbow flexion
b) Weak wrist and finger flexion
c) Weak shoulder abduction
d) Weak finger extension
Explanation: Compression of the median nerve in cubital fossa leads to weakness in wrist and finger flexion and sensory loss over lateral palm. Elbow flexion is mainly biceps (C5–C6), shoulder abduction by deltoid, finger extension by radial nerve. Hence, the correct answer is b) Weak wrist and finger flexion.