Thorax Practice Questions

Q: A Coronary CT angiogram shows a blood vessel marked as 'X' coursing around the left side of the heart. Small branches originating from this vessel supply the lateral surface of the heart and are called obtuse marginal branches. Identify the vessel marked as 'X'.

Left circumflex artery. ***Left circumflex artery*** - The vessel marked as 'X' is the **left circumflex artery (LCx)**, which branches from the left main coronary artery and courses around the **left side of the heart in the left atrioventricular groove**. - The **obtuse marginal branches** arising from it are characteristic branches that supply the **lateral wall of the left ventricle**. - The LCx supplies blood to the **left atrium, lateral and posterior walls of the left ventricle**, and sometimes the posterior interventricular septum. *Incorrect: Left anterior descending artery* - The LAD courses **anteriorly in the anterior interventricular groove**, not around the lateral aspect of the heart. - It gives off **diagonal and septal branches**, not obtuse marginal branches. - The LAD supplies the anterior wall of the left ventricle and anterior two-thirds of the interventricular septum. *Incorrect: Right coronary artery* - The RCA courses in the **right atrioventricular groove** on the right side of the heart. - It gives off **acute marginal branches** (not obtuse marginal branches) and supplies the right ventricle, right atrium, and (in right dominant systems) the inferior wall of the left ventricle. *Incorrect: Posterior descending artery* - The PDA is a **terminal branch** (usually of the RCA or less commonly the LCx), not a main coronary artery branch from the left coronary system. - It courses in the **posterior interventricular groove** and supplies the inferior interventricular septum.

Q: The commonly seen depression deformity of the chest wall is known as

Pectus excavatum. ***Pectus excavatum*** - This is a common congenital chest wall deformity characterized by an **inward depression of the sternum** and costal cartilages, creating a caved-in appearance of the chest. - It is often referred to as "funnel chest" due to the characteristic depression. *Kyphosis* - **Kyphosis** is an exaggerated, forward rounding of the back, often described as a hunchback. - It refers to a spinal curvature, not a depression of the chest wall itself. *Pectus carinatum* - **Pectus carinatum** is a chest wall deformity where the sternum protrudes outward, often referred to as "pigeon chest." - This is the opposite of a depression and involves a prominent, rather than sunken, chest. *Manubriosternal junction* - This term refers to the **normal anatomical landmark** where the manubrium meets the body of the sternum, also known as the sternal angle or angle of Louis. - It is not a deformity but a standard anatomical feature of the sternum.

Q: Inhaled foreign bodies are more likely to get lodged in the right main bronchus because

Right main bronchus is shorter, wider and nearly vertical. ***Right main bronchus is shorter, wider and nearly vertical*** - The **anatomical configuration** of the right main bronchus makes it a more direct continuation of the trachea. - Its **wider diameter** and **more vertical angle** allow foreign bodies to fall into it more easily due to gravity and airflow. *Left main bronchus is wider and shorter* - This statement is incorrect; the **left main bronchus** is actually **narrower and longer** than the right. - Its **more acute angle** stemming from the trachea also makes it less likely for foreign objects to lodge there directly. *Right main bronchus is shorter, narrower and lies horizontally in relation to trachea* - This statement is incorrect as the **right main bronchus** is indeed **shorter** but is **wider** and takes a **more vertical** course, not horizontal. - The description of being "narrower" and "horizontally" contradicts the anatomical characteristics that facilitate foreign body impaction. *Left main bronchus is narrow and longer* - This statement is anatomically correct for the left main bronchus; however, these characteristics make it **less likely** for foreign bodies to get lodged here. - The **narrower lumen** and **longer path**, combined with a more acute angle, make it a less direct route for inhaled objects.

Q: Dysphagia lusoria is a condition which results from

aberrant right subclavian artery. ***aberrant right subclavian artery*** - Dysphagia lusoria is specifically caused by compression of the **esophagus** by an **aberrant right subclavian artery** [2]. - This congenital anomaly involves the right subclavian artery arising from the distal aortic arch and passing behind the esophagus [2]. *oesophageal atresia* - **Oesophageal atresia** is a congenital condition where the esophagus ends in a blind pouch, preventing food from reaching the stomach [1]. - It usually presents in neonates with **vomiting** and **choking** during feeds, not progressive dysphagia in an adult [1]. *oesophageal web* - An **oesophageal web** is a thin, eccentric protrusion of normal esophageal tissue into the lumen, typically causing intermittent dysphagia to solids. - While it causes dysphagia, it is a structural abnormality within the esophageal lumen, not external compression. *corrosive stricture* - A **corrosive stricture** results from chemical burns to the esophagus, leading to scarring and narrowing of the lumen. - This is an acquired condition with a clear history of corrosive ingestion, unlike the congenital anomaly seen in dysphagia lusoria.

Q: Consider the following statements: Venacaval opening of the diaphragm, situated at the level of T8 transmits 1. inferior vena cava 2. vagus nerve 3. branches of the right phrenic nerve 4. thoracic duct Which of the statements given above are correct?

1 and 3. The **venacaval opening (caval hiatus)** is located at the level of **T8 vertebra** in the central tendon of the diaphragm. [1] **Statement 1: Inferior vena cava** ✓ - **CORRECT** - The inferior vena cava is the primary structure passing through the venacaval opening at T8. This opening is specifically designed to allow the IVC to pass from the abdomen into the thorax. **Statement 3: Branches of the right phrenic nerve** ✓ - **CORRECT** - The right phrenic nerve pierces the central tendon of the diaphragm near the venacaval opening. Some terminal branches of the right phrenic nerve pass through or adjacent to the caval opening to supply the inferior surface of the diaphragm [1]. *Statement 2: Vagus nerve* ✗ - *Incorrect* - The vagus nerves (anterior and posterior vagal trunks) pass through the **esophageal hiatus** at the level of **T10 vertebra**, not through the venacaval opening. [1] *Statement 4: Thoracic duct* ✗ - *Incorrect* - The thoracic duct passes through the **aortic hiatus** at the level of **T12 vertebra**, posterior to the diaphragm between the two crura. It does not pass through the venacaval opening. **Three major openings in the diaphragm:** - **T8** - Venacaval opening (IVC + right phrenic nerve branches) - **T10** - Esophageal hiatus (esophagus + vagus nerves) - **T12** - Aortic hiatus (aorta + thoracic duct + azygos vein) ***Therefore, statements 1 and 3 are correct.***

Q: Arrange lung hilar structure from anterior to posterior:- 1. Primary bronchus 2. Bronchial artery 3. Pulmonary vein 4. Pulmonary artery

3,4,1,2. ***3,4,1,2*** - This order represents the typical arrangement of major structures in the **lung hilum** from anterior to posterior: **pulmonary vein (most anterior)**, **pulmonary artery**, **primary bronchus**, and finally the **bronchial artery (most posterior)**. - The **pulmonary vein** is usually the most anterior structure, while the **bronchial artery** often runs along the posterior aspect of the bronchus [1]. *4,3,2,1* - This order incorrectly places the **pulmonary artery** as the most anterior structure, which is generally not the case in the hilum. - The **primary bronchus** is usually more posterior than the main pulmonary artery. *1,2,3,4* - This order is incorrect as it places the **primary bronchus** as the most anterior structure, which is anatomically inaccurate for the lung hilum. - The **pulmonary veins** are typically the most anterior hilar structures. *2,3,4,1* - This order incorrectly positions the **bronchial artery** as the most anterior component, while it is usually the most posterior or associated closely with the posterior aspect of the bronchus. - The **pulmonary vein** should be anterior to the pulmonary artery and bronchus.

Q: During a thoracotomy procedure, a surgeon needs to access the posterior mediastinum. Which of the following structures forms the anterior boundary of the posterior mediastinum?

Pericardial sac. ***Pericardial sac*** - The **pericardial sac** (and the diaphragm, inferiorly) forms the anterior boundary of the **posterior mediastinum** [1]. - This anatomical relationship is crucial for surgeons during thoracotomy to distinguish between the middle and posterior mediastinal compartments [1]. *Descending thoracic aorta* - The **descending thoracic aorta** is a large vessel located *within* the posterior mediastinum itself, typically running along its left side [2]. - Therefore, it is a content of the posterior mediastinum, not a boundary. *Azygos vein* - The **azygos vein** is also a major structure *within* the posterior mediastinum, running along the right side of the vertebral column. - It is a content, not a boundary, of this compartment. *Thoracic vertebrae* - The **thoracic vertebrae** form the *posterior* boundary of the posterior mediastinum [1]. - This anatomical landmark gives the posterior mediastinum its name and defines its dorsal limit.

Q: NOT a content of superior mediastinum

Left superior intercostal artery. ***Left superior intercostal artery*** - The **left superior intercostal artery** arises from the **costocervical trunk** (a branch of the subclavian artery) and is NOT considered a primary content of the superior mediastinum. - It descends to supply the **first and second (sometimes third) intercostal spaces** on the left side. - While it may pass near the superior mediastinum, it is anatomically classified with the **posterior mediastinum** structures. *Arch of aorta* - The **arch of the aorta** is a major structure within the **superior mediastinum** [1]. - It gives off three major branches: brachiocephalic trunk, left common carotid artery, and left subclavian artery [2]. - It extends from approximately the level of the **second costal cartilage** to the **lower border of T4 vertebra**. *Thymus* - The **thymus gland** is located in the **anterior mediastinum**, NOT the superior mediastinum [1]. - It lies posterior to the sternum and anterior to the pericardium and great vessels. - However, it may extend superiorly into the lower part of the neck, and in some classifications, its superior portion overlaps with the superior mediastinum [1]. *Pulmonary trunk* - The **pulmonary trunk** is located in the **middle mediastinum** within the pericardial sac, NOT the superior mediastinum [1]. - It originates from the **right ventricle** at a level below the superior mediastinum (which extends only to the sternal angle/T4-5 level). - It carries deoxygenated blood from the right ventricle to the lungs.

Q: Left anterior descending artery is a direct branch of

Left coronary artery. ***Left coronary artery*** - The left coronary artery (LCA) is a major coronary artery that arises from the **aorta** and quickly branches into two main arteries: the **left anterior descending (LAD) artery** [1] and the circumflex artery. - The LAD artery, also known as the **"widowmaker"**, supplies oxygenated blood to the **anterior wall of the left ventricle** and the interventricular septum, making it crucial for heart function. *Right coronary artery* - The **right coronary artery (RCA)** typically supplies the **right atrium**, most of the **right ventricle**, and the inferior wall of the left ventricle, which are distinct areas from the LAD's supply. - The RCA originates from the **right sinus of Valsalva** and travels in the atrioventricular groove, while the LAD originates from the left main coronary artery [1]. *Circumflex artery* - The circumflex artery is another main branch of the **left coronary artery**, typically supplying the **lateral and posterior walls of the left ventricle** and the left atrium. - While it branches from the same parent vessel as the LAD, it is a direct branch itself, not the origin of the LAD [1]. *Ascending aorta* - The ascending aorta is the initial part of the aorta that originates from the **left ventricle** and gives rise to the **coronary arteries** (both left and right coronary arteries). - It is the source from which the **left coronary artery** (and thus the LAD indirectly) originates, but it is not a direct branch itself.

Question 1

A Coronary CT angiogram shows a blood vessel marked as 'X' coursing around the left side of the heart. Small branches originating from this vessel supply the lateral surface of the heart and are called obtuse marginal branches. Identify the vessel marked as 'X'.

Accepted Answer

Left circumflex artery

Answer

Left anterior descending artery

Answer

Right coronary artery

Answer

Posterior descending artery

Question 2

The commonly seen depression deformity of the chest wall is known as

Accepted Answer

Pectus excavatum

Answer

Kyphosis

Answer

Pectus carinatum

Answer

Manubriosternal junction

Question 3

Inhaled foreign bodies are more likely to get lodged in the right main bronchus because

Accepted Answer

Right main bronchus is shorter, wider and nearly vertical

Answer

Left main bronchus is wider and shorter

Answer

Right main bronchus is shorter, narrower and lies horizontally in relation to trachea

Answer

Left main bronchus is narrow and longer

Question 4

Dysphagia lusoria is a condition which results from

Accepted Answer

aberrant right subclavian artery

Answer

oesophageal atresia

Answer

oesophageal web

Answer

corrosive stricture

Question 5

Consider the following statements: Venacaval opening of the diaphragm, situated at the level of T8 transmits

1. inferior vena cava 
2. vagus nerve 
3. branches of the right phrenic nerve 
4. thoracic duct Which of the statements given above are correct?

Accepted Answer

1 and 3

Answer

1 and 4

Answer

2 and 3

Answer

1 and 2

Question 6

Arrange lung hilar structure from anterior to posterior:-

1. Primary bronchus
2. Bronchial artery
3. Pulmonary vein
4. Pulmonary artery

Accepted Answer

3,4,1,2

Answer

4,3,2,1

Answer

1,2,3,4

Answer

2,3,4,1

Question 7

During a thoracotomy procedure, a surgeon needs to access the posterior mediastinum. Which of the following structures forms the anterior boundary of the posterior mediastinum?

Accepted Answer

Pericardial sac

Answer

Descending thoracic aorta

Answer

Azygos vein

Answer

Thoracic vertebrae

Answer

Sternum

Question 8

A 56-year-old man is brought to the emergency department 30 minutes after falling from a height of 3 feet onto a sharp metal fence pole. He is unconscious. Physical examination shows a wound on the upper margin of the right clavicle in the parasternal line that is 3-cm-deep. Which of the following is the most likely result of this patient's injury?

Accepted Answer

Pneumothorax due to pleural injury

Answer

Rotator cuff tear due to supraspinatus muscle injury

Answer

Trapezius muscle paresis due to spinal accessory nerve injury

Answer

Traumatic aneurysm due to internal carotid artery injury

Answer

Hemothorax due to azygos vein injury

Question 9

NOT a content of superior mediastinum

Accepted Answer

Left superior intercostal artery

Answer

Arch of aorta

Answer

Thymus

Answer

Pulmonary trunk

Question 10

Left anterior descending artery is a direct branch of

Accepted Answer

Left coronary artery

Answer

Right coronary artery

Answer

Circumflex artery

Answer

Ascending aorta

Thorax — MCQs

Thorax — MCQs

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