Chapter: Osteology; Topic: Femur; Subtopic: Ossification Centers of Femur
Keyword Definitions:
Ossification center: A site where bone tissue forms within cartilage or fibrous tissue during skeletal development.
Secondary ossification center: It appears after birth in the epiphyses and helps in the growth of bone in length.
Epiphysis: The end part of a long bone that grows separately from the shaft during development.
Femur: The longest and strongest bone in the human body, extending from the hip to the knee.
Growth plate: The cartilaginous region between the epiphysis and metaphysis responsible for bone elongation.
Lead Question – 2015
Secondary ossification center for lower end of femur?
a) Present at birth
b) Appears at 6 months of age
c) Appears at 1 year of age
d) Appears at 5 years of age
Explanation: The secondary ossification center for the lower end of the femur is unique because it is present at birth. This ossification center is used in forensic and radiological assessment to determine fetal viability and neonatal maturity. The lower femoral epiphysis ossifies before birth, while the upper one appears after 3–6 months. Hence, the correct answer is a) Present at birth.
Guessed Questions for NEET PG:
1. The primary ossification center of the femur appears at –
a) 7th week of intrauterine life
b) 5th month of intrauterine life
c) At birth
d) 6 months after birth
Explanation: The primary ossification center for the femoral shaft appears around the 7th week of intrauterine life. It forms the diaphysis, contributing to the bone’s early development and strength. Hence, the correct answer is a) 7th week of intrauterine life.
2. The secondary ossification center for the head of femur appears at –
a) Birth
b) 1 year
c) 3 years
d) 5 years
Explanation: The secondary ossification center for the head of femur appears around the first year after birth. It later fuses with the shaft during adolescence (around 18–20 years). Hence, the correct answer is b) 1 year.
3. The fusion of the lower end of femur occurs at –
a) 14 years
b) 16 years
c) 18 years
d) 20 years
Explanation: The lower end of the femur fuses with the shaft around 18–20 years of age. This fusion marks the end of longitudinal bone growth. Hence, the correct answer is d) 20 years.
4. Which of the following bones shows a secondary ossification center at birth?
a) Lower end of femur
b) Upper end of tibia
c) Lower end of humerus
d) Clavicle
Explanation: The lower end of femur and upper end of tibia are two long bones showing secondary ossification centers at birth. Among the options, the femur is most characteristic. Hence, the correct answer is a) Lower end of femur.
5. Radiograph showing an ossification center at the lower end of femur indicates –
a) Stillbirth
b) Viable fetus
c) Premature fetus
d) None
Explanation: The presence of an ossification center at the lower femoral epiphysis indicates fetal maturity and viability (>36 weeks). It helps in medico-legal determination of live birth. Hence, the correct answer is b) Viable fetus.
6. Clinical Case: A newborn X-ray shows ossification at lower end of femur. What does it signify?
a) The baby is at least 36 weeks old
b) Premature birth
c) Skeletal dysplasia
d) Delayed ossification
Explanation: The lower femoral epiphysis ossification appears around 36 weeks of intrauterine life. Hence, its presence in a newborn confirms term maturity. The correct answer is a) The baby is at least 36 weeks old.
7. Clinical Case: In a child, a fracture through the metaphysis of the distal femur can damage –
a) Epiphyseal plate
b) Articular cartilage
c) Primary ossification center
d) Periosteum only
Explanation: The metaphysis lies adjacent to the growth plate. A fracture here may disrupt the epiphyseal plate, leading to growth disturbances. Hence, the correct answer is a) Epiphyseal plate.
8. Clinical Case: A term infant shows absence of ossification at distal femur. This suggests –
a) Preterm delivery
b) Post-term infant
c) Nutritional deficiency
d) Skeletal anomaly
Explanation: The absence of ossification in the distal femoral epiphysis at birth indicates that the infant is preterm (less than 36 weeks gestation). Thus, the correct answer is a) Preterm delivery.
9. Clinical Case: A 2-year-old child suffers from septic arthritis of the knee. Which part of femur is likely affected?
a) Lower end epiphysis
b) Shaft
c) Upper end epiphysis
d) Metaphysis
Explanation: Infection from the knee joint can spread to the lower end epiphysis of the femur due to its proximity. In young children, the metaphyseal vessels communicate with the epiphysis, allowing such spread. Hence, the correct answer is a) Lower end epiphysis.
10. Clinical Case: In forensic examination, presence of distal femoral epiphyseal ossification center indicates –
a) Infant viability
b) Skeletal deformity
c) Postnatal infection
d) Nutritional rickets
Explanation: The distal femoral ossification center is a reliable indicator of fetal viability and term maturity. Its presence in autopsy or radiograph confirms that the fetus had reached full term before death. The correct answer is a) Infant viability.
Chapter: Anatomy of Lower Limb; Topic: Hip Joint; Subtopic: Ligaments of Hip Joint
Keyword Definitions:
Iliofemoral ligament: A strong Y-shaped ligament on the anterior surface of the hip joint that prevents hyperextension of the thigh.
Ischiofemoral ligament: A posterior ligament that limits internal rotation and adduction of the hip joint.
Pubofemoral ligament: A ligament that prevents excessive abduction and extension of the hip joint.
Hip joint: A ball-and-socket synovial joint formed between the acetabulum of the pelvis and the head of the femur.
Hyperextension: Movement beyond the normal range of extension at a joint, often prevented by strong ligaments.
Lead Question – 2015
Which of the following prevents hyperextension of thigh?
a) Ischiofemoral ligament
b) Iliofemoral ligament
c) Patellofemoral ligament
d) Puboischial ligament
Explanation: The iliofemoral ligament, also called the Y-shaped ligament of Bigelow, is the strongest ligament of the hip joint. It prevents hyperextension of the thigh during standing by maintaining upright posture without muscular effort. It runs from the anterior inferior iliac spine to the intertrochanteric line of the femur. Hence, the correct answer is b) Iliofemoral ligament.
Guessed Questions for NEET PG:
1. Which ligament of the hip joint is the strongest?
a) Ischiofemoral ligament
b) Iliofemoral ligament
c) Pubofemoral ligament
d) Transverse acetabular ligament
Explanation: The iliofemoral ligament is the strongest ligament in the human body. It resists hyperextension and stabilizes the hip during standing and walking. Its strength allows humans to maintain erect posture efficiently. Hence, the correct answer is b) Iliofemoral ligament.
2. Which ligament limits abduction and extension of the hip joint?
a) Ischiofemoral
b) Iliofemoral
c) Pubofemoral
d) Ligamentum teres
Explanation: The pubofemoral ligament lies anteroinferiorly, extending from the pubic bone to the femur, and restricts abduction and excessive extension. It reinforces the joint capsule anteriorly. Hence, the correct answer is c) Pubofemoral.
3. The ischiofemoral ligament limits which movement of the hip joint?
a) Extension
b) Adduction
c) Internal rotation
d) Flexion
Explanation: The ischiofemoral ligament spirals posteriorly from the ischium to the femur and primarily limits internal rotation and adduction. It also helps stabilize the femoral head within the acetabulum. Hence, the correct answer is c) Internal rotation.
4. Which ligament forms the Y-shaped structure at the anterior hip joint?
a) Ischiofemoral
b) Iliofemoral
c) Pubofemoral
d) Round ligament
Explanation: The iliofemoral ligament is Y-shaped and lies anteriorly. It connects the anterior inferior iliac spine with the intertrochanteric line, dividing into two limbs that resemble the letter ‘Y’. Hence, the correct answer is b) Iliofemoral ligament.
5. Clinical Case: A patient with weak iliofemoral ligament will most likely have difficulty in –
a) Standing upright
b) Flexing thigh
c) Rotating thigh
d) Abducting hip
Explanation: The iliofemoral ligament maintains erect posture by preventing hyperextension. Weakness or injury can cause difficulty in standing upright and require muscular effort for stability. Hence, the correct answer is a) Standing upright.
6. Clinical Case: During hip dislocation surgery, which ligament must be preserved to prevent hyperextension?
a) Iliofemoral
b) Ischiofemoral
c) Pubofemoral
d) Ligamentum teres
Explanation: The iliofemoral ligament prevents hyperextension; preserving it during surgery ensures hip stability in upright posture. Damage may cause postural instability or excessive extension. Hence, the correct answer is a) Iliofemoral.
7. Clinical Case: Injury to which ligament may cause excessive abduction and external rotation of hip?
a) Pubofemoral
b) Iliofemoral
c) Ischiofemoral
d) Transverse acetabular
Explanation: The pubofemoral ligament limits abduction; its injury causes uncontrolled abduction and external rotation. Hence, the correct answer is a) Pubofemoral ligament.
8. Clinical Case: A ballet dancer presents with hip instability and hyperextension. Which ligament is likely weak?
a) Pubofemoral
b) Iliofemoral
c) Ischiofemoral
d) Acetabular labrum
Explanation: Repeated overextension during ballet may overstretch the iliofemoral ligament, leading to hypermobility and anterior hip instability. Hence, the correct answer is b) Iliofemoral.
9. Clinical Case: A posterior dislocation of hip joint is prevented mainly by which ligament?
a) Iliofemoral
b) Ischiofemoral
c) Pubofemoral
d) Acetabular labrum
Explanation: The ischiofemoral ligament strengthens the posterior part of the capsule and helps prevent posterior dislocation. Hence, the correct answer is b) Ischiofemoral.
10. Clinical Case: A fracture of the acetabulum damaging the pubofemoral ligament will affect –
a) Limitation of abduction
b) Hip extension
c) Adduction
d) External rotation
Explanation: The pubofemoral ligament prevents excessive abduction and extension. Its rupture increases the range of abduction, compromising stability. Hence, the correct answer is a) Limitation of abduction.
Chapter: Thorax; Topic: Mediastinum; Subtopic: Boundaries of Mediastinum
Keyword Definitions:
Mediastinum: The central compartment of the thoracic cavity containing the heart, great vessels, trachea, and esophagus.
Superior Mediastinum: Upper portion of the mediastinum extending from thoracic inlet to the level of T4 vertebra.
Thoracic Inlet: The opening at the top of the thoracic cavity bounded by the first rib, manubrium, and first thoracic vertebra.
Transverse Thoracic Plane: An imaginary plane from the sternal angle to the intervertebral disc between T4 and T5 separating the superior and inferior mediastinum.
Lead Question – 2015
Lower limit of superior mediastinum is at which level –
a) T1
b) T4
c) T8
d) T10
Answer: b) T4
Explanation: The lower limit of the superior mediastinum corresponds to a transverse plane passing through the sternal angle to the intervertebral disc between the T4 and T5 vertebrae. This plane separates the superior and inferior mediastinum. The superior mediastinum contains major vessels like the arch of aorta, brachiocephalic veins, thymus, trachea, and esophagus.
1) Which structure is found at the level of the sternal angle?
a) Arch of aorta
b) Right atrium
c) Apex of heart
d) Pulmonary veins
Answer: a) Arch of aorta
Explanation: The sternal angle marks the level where the arch of the aorta begins and ends, and where the trachea bifurcates into bronchi. This anatomical landmark lies at the T4–T5 level, serving as an important reference point in thoracic anatomy and clinical procedures like mediastinal assessment and chest radiographs.
2) The trachea bifurcates at which vertebral level?
a) T2
b) T4–T5
c) T6
d) T8
Answer: b) T4–T5
Explanation: The tracheal bifurcation, forming the right and left main bronchi, occurs at the level of the sternal angle, corresponding to the intervertebral disc between T4 and T5. This site is clinically significant for bronchoscopy and airway management. The carina is located here and is sensitive to mechanical stimulation.
3) Which of the following structures is located in the superior mediastinum?
a) Heart
b) Thymus
c) Descending aorta
d) Pulmonary trunk
Answer: b) Thymus
Explanation: The superior mediastinum houses the thymus (especially in children), great veins, arch of aorta and its branches, trachea, esophagus, and thoracic duct. The heart and pulmonary trunk are located in the middle mediastinum. The thymus plays a role in T-cell development during early life.
4) Which vein drains into the superior vena cava within the superior mediastinum?
a) Azygos vein
b) Pulmonary vein
c) Inferior vena cava
d) Coronary sinus
Answer: a) Azygos vein
Explanation: The azygos vein ascends in the posterior thoracic wall and arches over the right lung root to drain into the superior vena cava within the superior mediastinum. This venous system forms an important collateral pathway between the superior and inferior vena cava in case of obstruction.
5) Which structure marks the superior boundary of the mediastinum?
a) Thoracic inlet
b) Sternal angle
c) Diaphragm
d) Clavicle
Answer: a) Thoracic inlet
Explanation: The thoracic inlet, bounded by the first thoracic vertebra, first rib, and manubrium, forms the upper boundary of the mediastinum. It serves as a passage for structures such as the trachea, esophagus, carotid arteries, and jugular veins entering or leaving the thoracic cavity.
6) (Clinical) A patient with a widened superior mediastinum on chest X-ray most likely has –
a) Aortic aneurysm
b) Pneumonia
c) Pneumothorax
d) Pleural effusion
Answer: a) Aortic aneurysm
Explanation: A widened superior mediastinum on chest radiograph typically indicates an aortic aneurysm or mediastinal mass. The superior mediastinum contains the aortic arch and great vessels, so aneurysmal dilatation can expand its contour. Clinical correlation and CT imaging help confirm the diagnosis and assess for rupture risk.
7) (Clinical) A stab wound at the sternal angle might damage which structure?
a) Arch of aorta
b) Left ventricle
c) Superior vena cava
d) Inferior vena cava
Answer: a) Arch of aorta
Explanation: The sternal angle marks the level where the ascending aorta becomes the arch of aorta. A penetrating injury at this level can damage the aortic arch or its branches, leading to massive hemorrhage. It’s an important reference in emergency thoracic trauma assessment.
8) (Clinical) Compression of the superior mediastinum can cause –
a) Dysphagia
b) Dyspnea
c) Venous congestion
d) All of the above
Answer: d) All of the above
Explanation: Superior mediastinal compression due to tumors or aneurysms may compress the trachea, esophagus, and veins, leading to dyspnea, dysphagia, and venous congestion (SVC syndrome). Symptoms depend on the extent of compression. Early diagnosis with CT/MRI is crucial for effective management and surgical planning.
9) The thoracic duct opens into which venous junction?
a) Right subclavian and right internal jugular
b) Left subclavian and left internal jugular
c) Brachiocephalic vein
d) Superior vena cava
Answer: b) Left subclavian and left internal jugular
Explanation: The thoracic duct drains lymph from the entire body except the right upper quadrant and empties into the venous system at the junction of the left subclavian and left internal jugular veins within the superior mediastinum. Damage here can cause chylothorax.
10) (Clinical) A tumor compressing the left recurrent laryngeal nerve in the superior mediastinum will cause –
a) Dysphagia
b) Hoarseness of voice
c) Facial paralysis
d) Stridor
Answer: b) Hoarseness of voice
Explanation: The left recurrent laryngeal nerve loops around the arch of the aorta in the superior mediastinum. Aortic aneurysm or mediastinal mass can compress this nerve, causing paralysis of vocal cords leading to hoarseness. Clinical evaluation includes laryngoscopy and imaging to locate the site of compression.
Chapter: Thorax; Topic: Venous System of Thorax; Subtopic: Azygos Venous System
Keyword Definitions:
Azygos Vein: A major vein running along the right side of the vertebral column that drains blood from the thoracic wall and upper lumbar region into the superior vena cava.
Superior Vena Cava (SVC): A large vein that carries deoxygenated blood from the upper body to the right atrium of the heart.
Hemiazygos Vein: A vein on the left side of the vertebral column that drains into the azygos vein.
Posterior Intercostal Veins: Veins draining the intercostal spaces; most drain into the azygos or hemiazygos veins.
Lead Question – 2015
Azygous vein drains into:
a) Right subcostal vein
b) Superior vena cava
c) Brachiocephalic vein
d) Right ascending lumbar vein
Answer: b) Superior vena cava
Explanation: The azygos vein ascends along the right side of the vertebral column, arching over the root of the right lung to drain into the superior vena cava before it enters the right atrium. It collects blood from the posterior thoracic wall, bronchial veins, and some abdominal veins, forming a collateral pathway between the superior and inferior vena cava.
1) The azygos vein is formed by the union of which veins?
a) Right subcostal and right ascending lumbar veins
b) Left subcostal and left ascending lumbar veins
c) Posterior intercostal and hemiazygos veins
d) Internal thoracic and phrenic veins
Answer: a) Right subcostal and right ascending lumbar veins
Explanation: The azygos vein begins at the level of T12 by the union of the right subcostal and right ascending lumbar veins. It enters the thorax through the aortic hiatus, ascends along the vertebral column, and drains into the superior vena cava, serving as a collateral venous route between the SVC and IVC.
2) The hemiazygos vein drains into the azygos vein at approximately which thoracic level?
a) T5
b) T8
c) T9
d) T12
Answer: c) T9
Explanation: The hemiazygos vein ascends on the left side of the vertebral column and crosses over to the right at the level of T8–T9 to join the azygos vein. This connection allows venous return from the lower left intercostal veins and serves as an important pathway for venous blood from the left posterior thoracic wall.
3) The accessory hemiazygos vein typically drains the –
a) Upper left intercostal veins
b) Lower left intercostal veins
c) Right intercostal veins
d) Mediastinal veins
Answer: a) Upper left intercostal veins
Explanation: The accessory hemiazygos vein drains the 4th to 8th left posterior intercostal veins and descends to join the azygos vein around the T7–T8 level. It provides venous drainage of the upper left thoracic wall and interconnects with both the hemiazygos and superior intercostal veins.
4) (Clinical) The azygos vein provides a collateral circulation between which two major veins?
a) Superior vena cava and inferior vena cava
b) Internal jugular and subclavian
c) Pulmonary veins and coronary sinus
d) Portal vein and hepatic veins
Answer: a) Superior vena cava and inferior vena cava
Explanation: The azygos vein system acts as an important collateral channel connecting the superior and inferior vena cava. In cases of obstruction of either vena cava, this venous network maintains venous return to the heart. This feature is particularly valuable in pathologies like SVC obstruction and cirrhosis-related portal hypertension.
5) The right superior intercostal vein drains into –
a) Azygos vein
b) Superior vena cava
c) Brachiocephalic vein
d) Internal thoracic vein
Answer: c) Brachiocephalic vein
Explanation: The right superior intercostal vein drains the 2nd to 4th posterior intercostal spaces and opens directly into the right brachiocephalic vein. It connects the azygos system with the upper thoracic venous drainage and is clinically significant during central venous catheterization and mediastinal pathology evaluations.
6) (Clinical) In a patient with superior vena cava obstruction, blood from the thorax is redirected through –
a) Azygos system
b) Pulmonary veins
c) Internal jugular veins
d) Coronary sinus
Answer: a) Azygos system
Explanation: In SVC obstruction, venous blood from the upper body is redirected via the azygos, hemiazygos, and accessory hemiazygos veins into the inferior vena cava, providing an alternate route to the heart. Dilated chest wall veins may be visible clinically, a hallmark of chronic SVC obstruction syndromes.
7) (Clinical) A penetrating injury to the right posterior thoracic wall near T5 may damage which vein?
a) Azygos vein
b) Hemiazygos vein
c) Accessory hemiazygos vein
d) Internal thoracic vein
Answer: a) Azygos vein
Explanation: The azygos vein lies to the right of the vertebral bodies and is vulnerable to injury in posterior thoracic trauma, especially between T4–T6 levels. Rupture can cause massive hemothorax. Recognition and surgical management are crucial, as unrecognized injury can result in severe mediastinal hemorrhage and shock.
8) Which intercostal veins drain directly into the azygos vein?
a) 5th–11th right posterior intercostal veins
b) 1st–4th right posterior intercostal veins
c) 2nd–6th left posterior intercostal veins
d) All intercostal veins
Answer: a) 5th–11th right posterior intercostal veins
Explanation: The azygos vein directly receives venous drainage from the 5th to 11th right posterior intercostal veins, bronchial veins, and esophageal veins. This direct drainage contributes significantly to the thoracic venous return and is key in maintaining thoracic wall circulation even when the SVC is compromised.
9) (Clinical) Enlargement of the azygos vein on imaging may indicate –
a) SVC obstruction
b) Pulmonary embolism
c) Aortic dissection
d) Pneumothorax
Answer: a) SVC obstruction
Explanation: Radiographic enlargement of the azygos vein suggests increased venous return via collateral circulation, typically due to superior vena cava obstruction. It appears as a paratracheal shadow on chest X-ray or enhanced structure on CT. Recognition aids in diagnosing thoracic venous obstructions and right heart dysfunction.
10) (Clinical) During central venous catheterization through the right internal jugular vein, which vein could inadvertently be entered leading to mediastinal injury?
a) Azygos vein
b) Hemiazygos vein
c) Superior intercostal vein
d) Internal thoracic vein
Answer: a) Azygos vein
Explanation: The azygos vein opens into the posterior aspect of the superior vena cava, and misdirection of a central venous catheter can inadvertently enter it, causing mediastinal perforation or hemothorax. Fluoroscopic or ultrasound guidance is recommended to prevent such complications during catheter placement.
Chapter: Thorax; Topic: Arterial System of Thorax; Subtopic: Arch of Aorta and Its Branches
Keyword Definitions:
Arch of Aorta: A curved continuation of the ascending aorta that gives rise to major arteries supplying the head, neck, and upper limbs.
Descending Thoracic Aorta: The part of the aorta that continues from the arch and runs down through the thorax, giving off intercostal arteries.
Brachiocephalic Trunk: The first branch of the aortic arch supplying the right arm and right side of the head and neck.
Left Common Carotid Artery: The second branch of the aortic arch that supplies the left side of the head and neck.
Left Subclavian Artery: The third branch of the aortic arch supplying the left upper limb.
Lead Question – 2015
Arch of aorta begins and ends at which level:
a) T2
b) T3
c) T4
d) T5
Answer: c) T4
Explanation: The arch of the aorta begins posterior to the right second sternocostal joint, continues upward, backward, and to the left, and ends at the level of the lower border of the T4 vertebra. It connects the ascending aorta to the descending thoracic aorta and gives rise to three major branches—brachiocephalic, left common carotid, and left subclavian arteries. The arch lies in the superior mediastinum and passes over the root of the left lung. Understanding this level is important for thoracic surgery and aortic pathology identification.
1) The arch of the aorta gives rise to how many major branches?
a) Two
b) Three
c) Four
d) One
Answer: b) Three
Explanation: The arch of the aorta gives rise to three branches: the brachiocephalic trunk, left common carotid artery, and left subclavian artery. These supply the head, neck, and upper limbs. Anatomical variations may occur, such as a common origin of the brachiocephalic and left common carotid arteries, known as a “bovine arch.”
2) The arch of aorta lies in which mediastinum?
a) Superior mediastinum
b) Middle mediastinum
c) Posterior mediastinum
d) Anterior mediastinum
Answer: a) Superior mediastinum
Explanation: The arch of the aorta is located in the superior mediastinum, extending from the ascending aorta to the descending aorta. It lies above the transverse thoracic plane at the level of the sternal angle (T4–T5). Knowledge of this location is crucial in imaging and cardiac surgery to avoid iatrogenic injury during procedures.
3) The ligamentum arteriosum connects the arch of the aorta to –
a) Pulmonary trunk
b) Left pulmonary artery
c) Right pulmonary artery
d) Superior vena cava
Answer: b) Left pulmonary artery
Explanation: The ligamentum arteriosum is a fibrous remnant of the fetal ductus arteriosus connecting the arch of the aorta to the left pulmonary artery. It serves as a landmark for the left recurrent laryngeal nerve, which hooks beneath it. Its proximity is clinically significant during thoracic surgeries and traumatic aortic injuries.
4) (Clinical) Compression of the left recurrent laryngeal nerve by the aortic arch can cause –
a) Hoarseness of voice
b) Cough
c) Difficulty swallowing
d) None
Answer: a) Hoarseness of voice
Explanation: The left recurrent laryngeal nerve loops under the arch of the aorta near the ligamentum arteriosum. Aneurysm or dilation of the aortic arch can compress this nerve, leading to paralysis of the left vocal cord and hoarseness. This condition is clinically known as Ortner’s syndrome or cardiovocal syndrome.
5) The plane of Louis (sternal angle) corresponds to which vertebral level?
a) T2–T3
b) T3–T4
c) T4–T5
d) T5–T6
Answer: c) T4–T5
Explanation: The sternal angle or plane of Louis corresponds to the junction of the manubrium and body of the sternum, at the level of T4–T5 vertebrae. It marks several anatomical landmarks, including the beginning and end of the aortic arch, bifurcation of the trachea, and upper border of the pericardium.
6) (Clinical) Aneurysm of the aortic arch commonly compresses which structure first?
a) Left recurrent laryngeal nerve
b) Esophagus
c) Trachea
d) Thoracic duct
Answer: a) Left recurrent laryngeal nerve
Explanation: Due to its close anatomical relationship, the left recurrent laryngeal nerve is often the first structure compressed by an aortic arch aneurysm, leading to hoarseness. Progressive enlargement may also compress the trachea and esophagus, causing respiratory distress or dysphagia. Early detection via imaging prevents complications.
7) The brachiocephalic trunk divides into –
a) Right subclavian and right common carotid arteries
b) Left subclavian and left common carotid arteries
c) Right and left carotid arteries
d) Vertebral and internal thoracic arteries
Answer: a) Right subclavian and right common carotid arteries
Explanation: The brachiocephalic trunk is the first branch of the aortic arch and divides behind the right sternoclavicular joint into the right subclavian and right common carotid arteries. It supplies the right upper limb and right side of the head and neck. It has no counterpart on the left side.
8) (Clinical) A newborn with failure of ductus arteriosus closure may develop –
a) Continuous machinery murmur
b) Silent murmur
c) Systolic murmur
d) Early diastolic murmur
Answer: a) Continuous machinery murmur
Explanation: Patent ductus arteriosus (PDA), a failure of closure of the fetal ductus arteriosus, causes a continuous “machinery” murmur due to shunting of blood from the aorta to the pulmonary artery. It can lead to pulmonary hypertension and heart failure if not treated surgically or pharmacologically with indomethacin.
9) Which structure lies anterior to the arch of the aorta?
a) Left brachiocephalic vein
b) Esophagus
c) Trachea
d) Thoracic duct
Answer: a) Left brachiocephalic vein
Explanation: The left brachiocephalic vein crosses anterior to the arch of the aorta as it travels obliquely to join the right brachiocephalic vein forming the superior vena cava. Understanding this relation is crucial during central venous access and mediastinal surgeries to prevent vascular injury.
10) (Clinical) A patient with dysphagia and dyspnea due to an aortic arch aneurysm has compression of which structure posteriorly?
a) Esophagus
b) Left pulmonary artery
c) Trachea
d) Thoracic duct
Answer: a) Esophagus
Explanation: The arch of the aorta lies anterior to the esophagus and trachea. In cases of aneurysm or dilation, it compresses the esophagus posteriorly, leading to difficulty in swallowing (dysphagia). Simultaneous tracheal compression can cause dyspnea. This clinical presentation is known as “dysphagia aortica.”
Chapter: Thorax; Topic: Arterial System of Thorax; Subtopic: Arch of Aorta and its Branches
Keyword Definitions:
Arch of Aorta: The curved portion of the aorta between the ascending and descending parts.
Brachiocephalic Artery: First major branch of the aortic arch that divides into the right subclavian and right common carotid arteries.
Common Carotid Artery: Supplies blood to the head and neck; right originates from the brachiocephalic trunk, left directly from the arch.
Subclavian Artery: Supplies the upper limb, neck, and brain.
Lead Question – 2015
Which among the following is NOT a branch of Arch of Aorta?
a) Brachiocephalic
b) Right common carotid
c) Left common carotid
d) Left Subclavian
Answer: b) Right common carotid
Explanation: The arch of aorta gives rise to three branches — the brachiocephalic trunk, the left common carotid, and the left subclavian arteries. The right common carotid artery arises from the brachiocephalic trunk, not directly from the arch. Therefore, option (b) is correct. These arteries supply the head, neck, and upper limbs.
Guessed Questions for NEET PG
1. The arch of aorta begins and ends at which vertebral level?
a) T2
b) T3
c) T4
d) T5
Answer: c) T4
Explanation: The arch of aorta begins at the level of the second right sternocostal joint, corresponding to T4 vertebra. It arches upward, backward, and to the left before descending at the T4 level. This anatomical relationship helps distinguish the boundaries of the superior mediastinum.
2. Which of the following arteries supplies the right upper limb?
a) Left subclavian artery
b) Right subclavian artery
c) Brachiocephalic artery
d) Right common carotid artery
Answer: b) Right subclavian artery
Explanation: The right subclavian artery supplies the right upper limb. It originates from the brachiocephalic trunk, a branch of the aortic arch. In contrast, the left subclavian arises directly from the arch, supplying the left upper limb. Both subclavian arteries continue as axillary arteries beyond the first rib.
3. Which branch of the aortic arch supplies blood to the left side of the head and neck?
a) Brachiocephalic trunk
b) Left common carotid artery
c) Left subclavian artery
d) Thyrocervical trunk
Answer: b) Left common carotid artery
Explanation: The left common carotid artery arises directly from the arch of aorta and supplies oxygenated blood to the left side of the head and neck. It later divides into external and internal carotid arteries to supply facial and intracranial structures respectively.
4. The right common carotid artery is a branch of which artery?
a) Arch of aorta
b) Left subclavian artery
c) Brachiocephalic trunk
d) Right subclavian artery
Answer: c) Brachiocephalic trunk
Explanation: The right common carotid artery arises from the brachiocephalic trunk, which is the first and largest branch of the arch of aorta. The trunk divides into the right common carotid and right subclavian arteries, supplying the head, neck, and right upper limb respectively.
5. Which of the following arteries does NOT originate from the arch of aorta?
a) Left subclavian
b) Left common carotid
c) Brachiocephalic trunk
d) Right subclavian
Answer: d) Right subclavian
Explanation: The right subclavian artery arises from the brachiocephalic trunk, while the left subclavian artery originates directly from the aortic arch. Hence, the right subclavian is not a direct branch of the arch of aorta.
6. (Clinical) A patient with aortic arch aneurysm compressing the left recurrent laryngeal nerve may present with:
a) Hoarseness of voice
b) Loss of tongue movement
c) Facial droop
d) Difficulty in swallowing
Answer: a) Hoarseness of voice
Explanation: The left recurrent laryngeal nerve loops around the arch of aorta near the ligamentum arteriosum. An aortic aneurysm can compress this nerve, causing vocal cord paralysis and hoarseness of voice. This is an important clinical feature of thoracic aortic pathology.
7. (Clinical) A traumatic rupture just distal to the left subclavian artery typically affects which part of the aorta?
a) Ascending aorta
b) Arch of aorta
c) Descending thoracic aorta
d) Abdominal aorta
Answer: c) Descending thoracic aorta
Explanation: Traumatic aortic rupture commonly occurs just distal to the origin of the left subclavian artery at the isthmus. This site is fixed and prone to shear stress during rapid deceleration injuries. The lesion may lead to massive internal bleeding and death if untreated.
8. (Clinical) A patient with left upper limb ischemia and dizziness on left arm use may have which vascular anomaly?
a) Subclavian steal syndrome
b) Coarctation of aorta
c) Aortic dissection
d) Pulmonary stenosis
Answer: a) Subclavian steal syndrome
Explanation: Subclavian steal syndrome occurs when proximal stenosis of the subclavian artery causes retrograde blood flow from the vertebral artery, leading to cerebral hypoperfusion and upper limb ischemia. It is commonly associated with the left subclavian artery near its origin from the arch.
9. (Clinical) A patient develops dyspnea due to compression of the trachea by a dilated aortic arch. Which structure lies anterior to the arch?
a) Trachea
b) Left lung root
c) Left brachiocephalic vein
d) Esophagus
Answer: c) Left brachiocephalic vein
Explanation: The left brachiocephalic vein crosses anterior to the arch of aorta, whereas the trachea and esophagus lie posterior. In aortic aneurysms, the trachea and esophagus are commonly compressed, leading to symptoms like dyspnea and dysphagia.
10. (Clinical) Post-stenotic dilatation near the ligamentum arteriosum indicates pathology in which part of the aorta?
a) Ascending aorta
b) Arch of aorta
c) Isthmus of aorta
d) Abdominal aorta
Answer: c) Isthmus of aorta
Explanation: The aortic isthmus is the segment between the origin of the left subclavian artery and the ligamentum arteriosum. It is a common site for coarctation or post-stenotic dilation due to hemodynamic stress. Recognition of this site is vital in congenital and acquired cardiovascular conditions.
Chapter: Thorax; Topic: Arterial System of Thorax; Subtopic: Variations of Arch of Aorta and its Branches
Keyword Definitions:
Arch of Aorta: The curved continuation of the ascending aorta connecting to the descending thoracic aorta, giving rise to major arteries supplying head, neck, and upper limbs.
Brachiocephalic Trunk: The first branch of the aortic arch that divides into the right subclavian and right common carotid arteries.
Left Vertebral Artery: A branch of the left subclavian artery, sometimes arising directly from the arch of aorta as a variation.
Subclavian Artery: A major artery supplying the upper limb, neck, and brain. Variation in its origin may cause vascular compression syndromes.
Lead Question – 2015
Which of the following represents the commonest variation in the arteries arising from the arch of aorta?
a) Absence of brachiocephalic trunk
b) Left vertebral artery arising from the arch
c) Presence of retroesophageal subclavian artery
d) Left common carotid artery arising from brachiocephalic trunk
Answer: b) Left vertebral artery arising from the arch
Explanation: The most frequent variation of the arch of aorta is the origin of the left vertebral artery directly from the arch between the left common carotid and left subclavian arteries. This occurs in about 5–10% of individuals. Such variations are usually asymptomatic but important in vascular surgeries and radiological interpretations to prevent inadvertent injury.
Guessed Questions for NEET PG
1. Normally, the arch of aorta gives rise to how many main branches?
a) Two
b) Three
c) Four
d) Five
Answer: b) Three
Explanation: The arch of aorta normally gives rise to three branches: the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. These supply the head, neck, and upper limbs. Occasionally, additional branches like the left vertebral artery may arise directly, representing common vascular variations.
2. Which artery is the first branch of the arch of aorta?
a) Left subclavian artery
b) Left common carotid artery
c) Brachiocephalic trunk
d) Left vertebral artery
Answer: c) Brachiocephalic trunk
Explanation: The brachiocephalic trunk, the first branch of the aortic arch, arises anteriorly and divides into the right subclavian and right common carotid arteries. It is unique to the right side as the left side has independent origins for corresponding arteries from the arch.
3. (Clinical) A patient’s CT angiogram shows the left vertebral artery arising directly from the arch of aorta. What is the clinical implication?
a) Usually asymptomatic
b) Causes dysphagia
c) Leads to cerebral ischemia
d) Results in aortic coarctation
Answer: a) Usually asymptomatic
Explanation: A left vertebral artery arising from the arch of aorta is a benign anatomical variant. It rarely causes symptoms but should be noted before vascular, neck, or thoracic surgery. Knowledge of this variation is essential during angiographic interpretation and endovascular procedures.
4. Which of the following arteries arises directly from the arch of aorta in normal anatomy?
a) Right common carotid
b) Left subclavian
c) Right subclavian
d) Internal carotid
Answer: b) Left subclavian
Explanation: The left subclavian artery arises directly from the arch of aorta, being its third branch. It supplies the left upper limb, neck, and part of the brain. The right subclavian, however, arises indirectly via the brachiocephalic trunk.
5. Which of the following is a rare variation of the aortic arch?
a) Double aortic arch
b) Left vertebral from arch
c) Bovine arch
d) Common carotid origin
Answer: a) Double aortic arch
Explanation: A double aortic arch is a congenital anomaly in which the aortic arch splits around the trachea and esophagus, forming a vascular ring. This can lead to respiratory distress or dysphagia in infancy, unlike other benign vascular variants.
6. (Clinical) A patient presents with dysphagia lusoria. Which vascular anomaly is most likely responsible?
a) Retroesophageal right subclavian artery
b) Left vertebral from arch
c) Bovine aortic arch
d) Double aortic arch
Answer: a) Retroesophageal right subclavian artery
Explanation: In dysphagia lusoria, an aberrant right subclavian artery arises distal to the left subclavian and passes posterior to the esophagus, compressing it. Though rare, it causes difficulty swallowing. This anomaly is significant in thoracic imaging and surgical dissection of the esophagus.
7. (Clinical) During cardiac surgery, the surgeon observes four branches from the arch of aorta. The additional branch is likely the:
a) Right subclavian artery
b) Left vertebral artery
c) Right common carotid
d) Left internal carotid
Answer: b) Left vertebral artery
Explanation: A fourth branch from the arch of aorta usually represents the left vertebral artery. This anatomical variant arises between the left common carotid and left subclavian arteries. Recognition of this helps avoid vascular injury during aortic and mediastinal procedures.
8. The “bovine arch” variation is characterized by:
a) Common origin of left common carotid and brachiocephalic trunk
b) Absence of brachiocephalic trunk
c) Presence of double aortic arch
d) Left vertebral arising from arch
Answer: a) Common origin of left common carotid and brachiocephalic trunk
Explanation: The bovine aortic arch is a common variation where the left common carotid artery shares a common origin with or arises from the brachiocephalic trunk. It is asymptomatic but important during endovascular procedures to prevent misplacement of catheters.
9. (Clinical) Which structure is most likely compressed in a double aortic arch anomaly?
a) Esophagus and trachea
b) Right subclavian artery
c) Left brachiocephalic vein
d) Pulmonary trunk
Answer: a) Esophagus and trachea
Explanation: A double aortic arch forms a vascular ring around the trachea and esophagus, leading to dysphagia and stridor in children. Surgical correction involves division of the smaller arch to relieve the compression and restore airway patency.
10. (Clinical) In aortic arch anomaly, the right subclavian artery arises last from the arch and passes behind the esophagus. What symptom may develop?
a) Hoarseness of voice
b) Difficulty in swallowing
c) Cyanosis
d) Arm edema
Answer: b) Difficulty in swallowing
Explanation: When the right subclavian artery arises abnormally as the last branch from the aortic arch and courses posterior to the esophagus, it compresses the esophagus, causing dysphagia (dysphagia lusoria). It is usually an incidental radiological finding but may require intervention in symptomatic cases.
Chapter: Thorax; Topic: Intercostal Nerves; Subtopic: Thoracic Nerve Distribution
Keyword Definitions:
• Intercostal nerves: Ventral rami of thoracic spinal nerves supplying muscles and skin between ribs.
• Thoracic spinal nerves: Twelve pairs emerging from thoracic segments of the spinal cord.
• Brachial plexus: Nerve network supplying upper limb.
• Ventral rami: Branches of spinal nerves that supply anterior and lateral trunk.
• Dorsal rami: Branches supplying deep back muscles and skin of the back.
Lead Question – 2015
Intercostal nerve is a branch of?
a) Brachial plexus
b) Dorsal rami of thoracic spinal nerves
c) Ventral rami of thoracic spinal nerves
d) Ventral rami of cervical spinal nerves
Answer: c) Ventral rami of thoracic spinal nerves
Explanation: Intercostal nerves are the anterior primary rami of thoracic spinal nerves T1–T11, supplying intercostal muscles and overlying skin. Each runs in the costal groove with blood vessels. Unlike other spinal nerves, they do not form plexuses. The subcostal nerve (T12) lies below the 12th rib. Hence, option c is correct.
1) Which of the following nerves supply intercostal muscles?
a) Sympathetic nerves
b) Intercostal nerves
c) Phrenic nerve
d) Vagus nerve
Answer: b) Intercostal nerves
Explanation: The intercostal muscles—external, internal, and innermost—are innervated by intercostal nerves derived from the ventral rami of thoracic spinal nerves. These nerves control muscle contraction during respiration, facilitating rib cage expansion and contraction. Sympathetic nerves regulate visceral functions, not skeletal muscles.
2) The subcostal nerve corresponds to which thoracic spinal nerve?
a) T11
b) T12
c) T10
d) T9
Answer: b) T12
Explanation: The subcostal nerve is the ventral ramus of the T12 spinal nerve. It lies below the 12th rib and supplies abdominal wall muscles and overlying skin. It communicates with the iliohypogastric and ilioinguinal nerves, forming part of the innervation to the anterior abdominal wall and lateral trunk.
3) A patient has numbness over the skin between the 5th and 6th ribs. Which nerve is affected?
a) T4
b) T5
c) T6
d) T7
Answer: b) T5
Explanation: The intercostal nerve corresponding to the rib space supplies the overlying skin. The 5th intercostal nerve, derived from the T5 ventral ramus, supplies the intercostal space between the 5th and 6th ribs. Damage to this nerve causes sensory loss and mild intercostal muscle weakness at that segmental level.
4) The first intercostal nerve differs from others because:
a) It gives a lateral cutaneous branch
b) It supplies the skin of the arm
c) It has no anterior cutaneous branch
d) It joins the brachial plexus
Answer: d) It joins the brachial plexus
Explanation: The first intercostal nerve largely contributes to the brachial plexus and does not give a typical lateral cutaneous branch. It mainly helps innervate upper limb muscles through communication with the lower trunk of the brachial plexus. Only a small intercostal segment remains in the thorax.
5) The intercostobrachial nerve is derived from:
a) 1st thoracic nerve
b) 2nd thoracic nerve
c) 3rd thoracic nerve
d) 4th thoracic nerve
Answer: b) 2nd thoracic nerve
Explanation: The intercostobrachial nerve originates from the lateral cutaneous branch of the 2nd intercostal nerve (T2). It supplies the skin of the axilla and medial side of the upper arm. Damage during axillary dissection can cause sensory loss in this region. It’s an important landmark in breast surgery.
6) A thoracic wall injury damaging the 3rd intercostal nerve would cause weakness in:
a) Scalene muscles
b) Intercostal muscles between 3rd and 4th ribs
c) Diaphragm
d) Serratus anterior
Answer: b) Intercostal muscles between 3rd and 4th ribs
Explanation: The 3rd intercostal nerve supplies the intercostal muscles and overlying skin between the 3rd and 4th ribs. Injury causes weakness in chest wall expansion and localized sensory loss. Diaphragm and serratus anterior are innervated by phrenic and long thoracic nerves respectively, not intercostal nerves.
7) The lateral cutaneous branch of an intercostal nerve supplies:
a) Skin over the back
b) Skin of the chest and lateral thoracic wall
c) Skin of abdomen only
d) Diaphragm
Answer: b) Skin of the chest and lateral thoracic wall
Explanation: Each intercostal nerve gives a lateral cutaneous branch that pierces the intercostal muscles to supply the skin of the lateral thoracic and abdominal wall. It further divides into anterior and posterior branches. The skin over the back is supplied by dorsal rami of spinal nerves.
8) Clinical: During thoracotomy, which structure is most at risk if incision is made along the upper border of a rib?
a) Intercostal vein
b) Intercostal artery
c) Intercostal nerve
d) All of the above
Answer: d) All of the above
Explanation: Intercostal vein, artery, and nerve lie together in the costal groove along the inferior border of each rib, arranged as vein–artery–nerve (VAN). Therefore, incisions are made along the superior border of a rib to prevent injury to this neurovascular bundle during surgical procedures like thoracotomy or chest tube insertion.
9) Clinical: A stab wound in the 9th intercostal space along the midaxillary line may damage nerves supplying:
a) Skin of the upper arm
b) Abdominal wall
c) Diaphragm
d) Shoulder
Answer: b) Abdominal wall
Explanation: Lower intercostal nerves (T7–T11) continue beyond the costal margin to supply the abdominal wall muscles and overlying skin. A stab injury in the 9th intercostal space damages these nerves, resulting in weakness of abdominal wall muscles and loss of sensation in the corresponding skin region.
10) Clinical: A patient with herpes zoster along the T8 dermatome experiences pain along:
a) Shoulder region
b) Umbilical level
c) Above umbilicus
d) Below umbilicus
Answer: c) Above umbilicus
Explanation: The T8 dermatome corresponds to the skin area just above the umbilicus. Herpes zoster virus affects sensory ganglia, producing painful vesicular eruptions along the affected dermatome. Thoracic dermatomes help in clinical localization of spinal nerve involvement. Hence, pain above the umbilicus corresponds to T8 dermatome.
Chapter: Upper Digestive System; Topic: Pharynx and Esophagus; Subtopic: Cricopharynx and Esophageal Constrictions
Keyword Definitions:
• Cricopharynx: The upper esophageal sphincter formed by cricopharyngeus muscle, controlling entry of food into the esophagus.
• Esophagus: Muscular tube connecting the pharynx to the stomach, about 25 cm long.
• Constrictions: Narrow points in the esophagus where foreign bodies can lodge.
• Incisor teeth: The front teeth used as a reference for measuring distances in endoscopy.
• Upper esophageal sphincter: Circular muscle at the junction of pharynx and esophagus preventing air entry and reflux.
Lead Question – 2015
Distance of cricopharynx from incisor teeth:
a) 15 cm
b) 22.5 cm
c) 27.5 cm
d) 40 cm
Answer: b) 22.5 cm
Explanation: The cricopharynx lies approximately 22–23 cm from the upper incisor teeth. It marks the beginning of the esophagus and forms the upper esophageal sphincter. This point is an important site of constriction where foreign bodies or corrosive injuries commonly lodge. Knowledge of these measurements aids in safe endoscopic procedures.
1) Total length of the esophagus in adults is approximately:
a) 15 cm
b) 20 cm
c) 25 cm
d) 30 cm
Answer: c) 25 cm
Explanation: The adult esophagus measures about 25 cm in length, extending from the lower border of the cricoid cartilage (C6) to the cardiac orifice of the stomach (T11). It passes through the diaphragm at 40 cm from the incisor teeth. Understanding its length is vital for diagnostic endoscopy and tube placement.
2) At what vertebral level does the esophagus begin?
a) C4
b) C5
c) C6
d) C7
Answer: c) C6
Explanation: The esophagus begins at the lower border of the cricoid cartilage, corresponding to the C6 vertebral level. This point is continuous with the laryngopharynx above and is an important surgical landmark in neck surgeries and endoscopic anatomy. The esophagus continues downward to enter the stomach at T11 level.
3) Clinical: A foreign body stuck 22 cm from the incisor teeth during endoscopy is located at:
a) Aortic constriction
b) Cricopharyngeal constriction
c) Diaphragmatic constriction
d) Gastroesophageal junction
Answer: b) Cricopharyngeal constriction
Explanation: The first physiological constriction of the esophagus occurs at the cricopharyngeus muscle, about 22–23 cm from the incisor teeth. Foreign bodies commonly lodge here because it is the narrowest part of the esophagus. Proper identification prevents accidental injury during endoscopic removal or dilation procedures.
4) Which of the following is NOT an anatomical constriction of the esophagus?
a) Cricopharyngeal constriction
b) Aortic arch constriction
c) Tracheal constriction
d) Diaphragmatic constriction
Answer: c) Tracheal constriction
Explanation: The esophagus has four constrictions: at the cricopharyngeus (22 cm), by the aortic arch (27.5 cm), by the left bronchus (32.5 cm), and at the diaphragm (40 cm). The trachea does not cause any constriction; it lies anteriorly. These points are essential for radiographic localization and clinical interpretation of esophageal pathology.
5) The esophagus pierces the diaphragm at what distance from the incisor teeth?
a) 30 cm
b) 35 cm
c) 40 cm
d) 45 cm
Answer: c) 40 cm
Explanation: The esophagus passes through the diaphragm at the esophageal hiatus at a distance of about 40 cm from the incisor teeth. This is the lowest constriction point before entering the stomach. The region is prone to hiatal hernia and reflux esophagitis, hence its clinical importance in endoscopic evaluation.
6) Clinical: A patient with dysphagia due to achalasia cardia has failure of relaxation of:
a) Cricopharyngeus muscle
b) Pharyngeal constrictor muscles
c) Lower esophageal sphincter
d) Palatopharyngeus muscle
Answer: c) Lower esophageal sphincter
Explanation: Achalasia cardia is a disorder caused by failure of relaxation of the lower esophageal sphincter (LES) due to loss of ganglion cells in the myenteric plexus. It leads to progressive dysphagia and food stasis. The condition is diagnosed by manometry and barium swallow showing a “bird’s beak” appearance.
7) Clinical: During esophagoscopy, at what distance would an obstruction by the aortic arch typically be seen?
a) 15 cm
b) 22.5 cm
c) 27.5 cm
d) 40 cm
Answer: c) 27.5 cm
Explanation: The aortic arch crosses the esophagus at approximately 27.5 cm from the incisor teeth, forming the second constriction. It is one of the narrowest points, making it a site for impaction of swallowed objects. Awareness of these constriction levels is essential during diagnostic and therapeutic endoscopy.
8) The esophagus is supplied by which nerve for motor control?
a) Glossopharyngeal nerve
b) Hypoglossal nerve
c) Vagus nerve
d) Accessory nerve
Answer: c) Vagus nerve
Explanation: The motor fibers of the esophagus are supplied by the vagus nerve (cranial nerve X). The upper part receives fibers via the recurrent laryngeal branch, and the lower part through the esophageal plexus. These nerves coordinate peristaltic movements, essential for smooth passage of food into the stomach during swallowing.
9) Clinical: A patient complains of difficulty in swallowing solids and liquids with regurgitation. Barium swallow reveals a constriction at 40 cm from the incisor teeth. The likely diagnosis is:
a) Cricopharyngeal spasm
b) Hiatus hernia
c) Achalasia cardia
d) Carcinoma at upper esophagus
Answer: c) Achalasia cardia
Explanation: The lower esophageal sphincter at 40 cm corresponds to the site affected in achalasia cardia, where peristalsis is lost, and the sphincter fails to relax. This results in functional obstruction at the gastroesophageal junction, seen as a “bird’s beak” appearance on barium swallow. It causes dysphagia and regurgitation of food.
10) Clinical: A surgeon performing cervical esophagotomy must identify which landmark to locate the cricopharynx?
a) Cricoid cartilage
b) Thyroid cartilage
c) Hyoid bone
d) Jugular notch
Answer: a) Cricoid cartilage
Explanation: The cricopharynx corresponds anatomically to the lower border of the cricoid cartilage at the C6 vertebral level. During cervical esophagotomy, this landmark helps avoid damage to the recurrent laryngeal nerve and ensures accurate entry into the esophagus. Hence, cricoid cartilage is a crucial surgical reference point.
Chapter: Cardiovascular System; Topic: Coronary Circulation; Subtopic: Blood Supply of Interventricular Septum
Keyword Definitions:
• Interventricular septum: The muscular wall separating the right and left ventricles of the heart.
• Coronary arteries: Arteries arising from the aortic sinuses that supply the myocardium.
• Left anterior descending artery (LAD): A branch of the left coronary artery supplying the anterior interventricular septum.
• Right coronary artery (RCA): Supplies the right atrium, right ventricle, and posterior part of the septum.
• Posterior descending artery (PDA): Supplies the posterior one-third of the interventricular septum.
Lead Question – 2015
Anterior part of interventricular septum is supplied by:
a) Right coronary artery
b) Left coronary artery
c) Posterior descending coronary artery
d) None
Answer: b) Left coronary artery
Explanation: The anterior two-thirds of the interventricular septum is supplied by the left anterior descending branch of the left coronary artery. The posterior one-third receives blood from the posterior descending artery, usually a branch of the right coronary artery. The LAD is crucial for cardiac conduction, as it nourishes the bundle branches and part of the AV bundle.
1) Which artery mainly supplies the posterior one-third of the interventricular septum?
a) Circumflex artery
b) Right coronary artery
c) Left anterior descending artery
d) Left coronary artery
Answer: b) Right coronary artery
Explanation: The right coronary artery, through its posterior descending branch, supplies the posterior one-third of the interventricular septum. This posterior part includes the posterior fascicle of the left bundle branch. Occlusion of this artery can result in conduction abnormalities, bradycardia, and right ventricular infarction depending on dominance of circulation.
2) Clinical: A patient with anterior wall myocardial infarction most likely has blockage of which artery?
a) Left anterior descending artery
b) Circumflex artery
c) Right coronary artery
d) Marginal artery
Answer: a) Left anterior descending artery
Explanation: The left anterior descending (LAD) artery, also called the anterior interventricular artery, supplies the anterior wall of the left ventricle and anterior two-thirds of the septum. Blockage of the LAD is the most common cause of anterior wall myocardial infarction and is often termed the “widow-maker” due to its high mortality risk.
3) Which of the following arteries supplies the SA node in most individuals?
a) Left coronary artery
b) Right coronary artery
c) Circumflex branch
d) Left anterior descending artery
Answer: b) Right coronary artery
Explanation: In approximately 60% of people, the sinoatrial (SA) node receives its blood supply from a branch of the right coronary artery. In the remaining 40%, it arises from the circumflex branch of the left coronary artery. Knowledge of this variation is important in coronary bypass surgery and angiographic interpretation.
4) Clinical: A block in the LAD artery leads to infarction of which conduction structure?
a) SA node
b) AV node
c) Bundle of His
d) Posterior fascicle
Answer: c) Bundle of His
Explanation: The LAD supplies the anterior two-thirds of the interventricular septum, which contains the bundle of His and its branches. Blockage of this artery can cause bundle branch block or complete heart block due to ischemia of the conduction system. This emphasizes the critical importance of LAD in cardiac physiology and pathology.
5) Which coronary artery is dominant if the posterior descending artery arises from the right coronary artery?
a) Left dominant
b) Right dominant
c) Co-dominant
d) None
Answer: b) Right dominant
Explanation: In a right-dominant circulation, the posterior descending artery arises from the right coronary artery. This pattern is found in about 70% of individuals. It determines which artery supplies the posterior interventricular septum and the diaphragmatic surface of the heart, influencing the site of infarction in coronary occlusions.
6) Clinical: A patient with inferior wall myocardial infarction develops bradycardia. The likely artery involved is:
a) Left anterior descending artery
b) Left circumflex artery
c) Right coronary artery
d) Marginal artery
Answer: c) Right coronary artery
Explanation: The right coronary artery supplies the SA and AV nodes in most individuals. Inferior wall infarctions due to RCA occlusion can impair nodal perfusion, leading to bradycardia and conduction blocks. This clinical association helps localize the arterial territory affected during ECG interpretation and management of acute coronary syndromes.
7) The circumflex branch of the left coronary artery supplies:
a) Right atrium
b) Anterior interventricular septum
c) Posterior surface of left ventricle
d) Right ventricle
Answer: c) Posterior surface of left ventricle
Explanation: The circumflex branch of the left coronary artery winds around the left border of the heart in the atrioventricular groove to supply the posterior surface of the left ventricle. In left-dominant hearts, it also gives rise to the posterior descending artery. It plays a role in supplying the left atrium and left ventricle.
8) Clinical: Occlusion of which artery is most likely to cause septal wall infarction?
a) Posterior descending artery
b) Left anterior descending artery
c) Circumflex artery
d) Right coronary artery
Answer: b) Left anterior descending artery
Explanation: Septal wall infarction results from occlusion of the LAD artery, which supplies the anterior two-thirds of the interventricular septum. This affects the left bundle branch and anterior papillary muscle. Patients present with ECG changes in the precordial leads (V1–V4), making it a classic presentation of anterior or septal myocardial infarction.
9) Which coronary artery forms the posterior interventricular groove in a right-dominant heart?
a) Left coronary artery
b) Posterior descending artery
c) Circumflex artery
d) Left anterior descending artery
Answer: b) Posterior descending artery
Explanation: The posterior descending artery (PDA) lies in the posterior interventricular groove, supplying the posterior third of the septum. In right-dominant hearts, it is a branch of the right coronary artery, while in left-dominant hearts, it arises from the circumflex branch of the left coronary artery. It plays a key role in posterior circulation.
10) Clinical: During coronary angiography, a cardiologist identifies an occlusion at the beginning of the LAD artery. Which region of the heart is most endangered?
a) Right atrium
b) Left ventricle anterior wall and septum
c) Right ventricle
d) Posterior wall of left ventricle
Answer: b) Left ventricle anterior wall and septum
Explanation: The LAD artery supplies the anterior wall of the left ventricle and anterior two-thirds of the interventricular septum. Blockage near its origin can lead to massive anterior wall infarction and conduction defects. This is why LAD is referred to as the “widow-maker” artery, emphasizing its clinical and surgical significance.