Thorax Practice Questions

Q: The aortic hiatus is formed by the right and left crura of the diaphragm. Which of the following structures does NOT pass through the aortic hiatus?

Left gastric vein. ***Left gastric vein*** - The **left gastric vein** is part of the **portal venous system** and drains into the portal vein. - It **does NOT pass through the diaphragm** via the aortic hiatus or any other diaphragmatic opening. - It has **no anatomical relationship** with the aortic hiatus, making it the best answer to this question. *Thoracic duct* - The **thoracic duct** is the largest lymphatic vessel in the body and **passes through the aortic hiatus** along with the aorta. - It ascends through the aortic hiatus at the **T12 vertebral level** to eventually drain into the left subclavian vein. - It lies posterior to the aorta as it traverses the hiatus. *Left vagus nerve* - The **left vagus nerve** does NOT pass through the aortic hiatus, but it **does pass through the esophageal hiatus** at the T10 level. - It contributes to the **anterior vagal trunk** as it enters the abdomen with the esophagus. - While this structure doesn't pass through the aortic hiatus, it does traverse the diaphragm through a different opening, making it a less definitive answer than the left gastric vein. *Azygos vein* - The **azygos vein** typically **passes through the aortic hiatus** alongside the aorta and thoracic duct. - It may occasionally pass through a separate opening in the right crus of the diaphragm. - It collects deoxygenated blood from the posterior walls of the thorax and abdomen before draining into the superior vena cava.

Q: The ventral surface of the adult heart, as seen on gross examination or radiography, is comprised primarily of the

Right ventricle. The ventral surface of the adult heart, as seen on gross examination or radiography, is comprised primarily of the ***Right ventricle*** - The **right ventricle** forms the majority of the **anterior (ventral) surface** of the adult heart, lying directly behind the sternum and costal cartilages. - This anatomical position makes it the most superficial chamber and readily visible on gross dissection or anterior-posterior radiographic views of the chest. *Left atrium* - The **left atrium** is the most **posterior chamber** of the heart, forming the heart's base and receiving pulmonary veins [1]. - It is not visible on the ventral surface and is instead located closer to the esophagus and vertebral column [1]. *Left ventricle* - While a significant chamber, the **left ventricle** primarily forms the **apex** of the heart and the **left border**, with only a small portion contributing to the anterior surface. - Its bulk is more directed **posterolaterally** and to the left. *Inferior vena cava* - The **inferior vena cava** is a large vein that drains into the **right atrium**, not a chamber that forms a significant portion of the heart's ventral surface. - Its presence is more associated with the **diaphragmatic surface** of the heart as it enters the posterior part of the right atrium [2].

Q: Which of the following structures anchors the breast tissue to the overlying skin?

Cooper's ligaments. ***Cooper's ligaments (Correct)*** - These are **fibrous bands** that extend from the deep fascia over the pectoralis major muscle through the breast tissue to the dermis of the skin, providing **support and anchorage** [2]. - They help maintain the **shape and structure** of the breast. - Also known as the **suspensory ligaments of Cooper**, they are the key structures that directly anchor breast tissue to the overlying skin [2]. *Cruciate ligaments (Incorrect)* - These ligaments are found in the **knee joint**, specifically the **anterior cruciate ligament (ACL)** and **posterior cruciate ligament (PCL)**, and are not associated with breast anatomy. - They are crucial for knee stability, preventing excessive **forward and backward movement** of the tibia relative to the femur. *Falciform ligament (Incorrect)* - The **falciform ligament** is a peritoneal fold that attaches the liver to the anterior abdominal wall and diaphragm. - It is an **intra-abdominal structure** with no anatomical connection to the breast. *Pectoralis major fascia (Incorrect)* - The **pectoralis major fascia** is a layer of connective tissue that covers the pectoralis major muscle, providing a deep anchor point for the breast [1]. - However, it is the **Cooper's ligaments** that extend from this fascia *through* the breast tissue to the skin, thus directly anchoring the breast to the overlying skin [2].

Q: The root of the right lung does not lie behind which one of the following?

Right vagus. ***Right vagus*** - The **right vagus nerve** passes **behind (posterior to) the root of the right lung** [1]. - Therefore, the root of the right lung lies **in front of** the right vagus nerve, NOT behind it. - This is the correct answer to the question asking what the root does NOT lie behind. *Phrenic nerve* - The **right phrenic nerve** passes **in front of (anterior to) the root of the right lung**, running between the fibrous pericardium and the mediastinal pleura [1]. - Hence, the root of the right lung **does lie behind** the right phrenic nerve. *Superior vena cava* - The **superior vena cava (SVC)** is situated **anterior to the root of the right lung** [1]. - Consequently, the root of the right lung **does lie behind** the superior vena cava. *Right atrium* - The **right atrium** is located **anterior to the root of the right lung**. - The root of the right lung **does lie behind** the right atrium.

Q: Which myocardial region is most likely to experience ischemia following occlusion of the left anterior descending artery?

Anterior wall. **Anterior wall** - The **left anterior descending (LAD) artery** is a major coronary artery that supplies blood to the **anterior two-thirds of the interventricular septum** and the **anterior wall of the left ventricle**. - Occlusion of the LAD artery, often referred to as the "**widowmaker**," leads to significant ischemia and infarction in these regions due to loss of blood supply [1]. *Left atrium* - The **left atrium** is primarily supplied by branches of the **circumflex artery** and occasionally by the right coronary artery. - Involvement of the left atrium is highly unlikely with isolated LAD occlusion. *Right ventricle* - The **right ventricle** is predominantly supplied by the **right coronary artery (RCA)**. - While there can be some collateral flow, isolated LAD occlusion typically spares the right ventricle. *Interatrial septum* - The **interatrial septum** receives blood supply from branches of both the **right and left coronary arteries**, but mainly from the **right coronary artery**. - Ischemia in this region is uncommon with LAD occlusion, which primarily affects the ventricular septum.

Q: Which of the following is an anterior mediastinal tumor?

Thymoma. ***Thymoma*** - **Thymomas** originate from the **thymus gland**, which is located in the **anterior mediastinum** [1]. - They are the **most common primary tumor** of the anterior mediastinum in adults and can be associated with **myasthenia gravis** (30-50% of cases) [1]. - Thymoma is the classic anterior mediastinal tumor and the most frequent solid mass in this compartment [1]. *Lymphoma* - **Lymphoma** (particularly **Hodgkin lymphoma** and **primary mediastinal B-cell lymphoma**) is also a well-recognized **anterior mediastinal tumor** [1]. - It represents the second most common cause of anterior mediastinal masses, especially in younger patients [1]. - The mnemonic "4 T's" of anterior mediastinum includes "Terrible lymphoma" alongside Thymoma, Thyroid, and Teratoma [1]. - While both thymoma and lymphoma can occur in the anterior mediastinum, **thymoma is the most common primary tumor** in this location [1]. *Aortic aneurysm* - An **aortic aneurysm** is an abnormal dilatation of the **aorta**, which is situated in the **middle and posterior mediastinum**. - It is a vascular pathology, not a tumor, and does not arise from the anterior mediastinal compartment. *Bronchogenic cyst* - **Bronchogenic cysts** are congenital foregut malformations typically found in the **middle mediastinum**, often near the carina or main bronchi. - They are fluid-filled developmental anomalies, not solid tumors of the anterior compartment.

Q: Which of the following is related to the mediastinal part of the right lung?

SVC. ***SVC*** - The **superior vena cava (SVC)** lies to the right side of the mediastinum and is intimately related to the mediastinal surface of the **right lung** [1]. - The SVC drains into the **right atrium** and forms an important landmark in the superior mediastinum, immediately adjacent to the right lung hilum [1]. - Creates a prominent **vertical groove** on the mediastinal surface of the right lung [1]. *Arch of aorta* - The **arch of aorta** is located in the superior mediastinum but lies to the **left** of the trachea and mediastinal structures, thus relating more to the **left lung**. - It arches over the root of the left lung and creates an impression on the **left mediastinal surface**, not the right. *Pulmonary trunk* - The **pulmonary trunk** arises from the right ventricle and ascends in the mediastinum, but it is primarily situated **anterior and to the left** of the ascending aorta. - It bifurcates into the right and left pulmonary arteries **anterior to the left main bronchus**, creating impressions mainly on the **left lung's mediastinal surface**. *Left atrium* - The **left atrium** forms the base of the heart and is located on the **left and posterior** aspect of the mediastinum. - It creates an impression on the **left lung's mediastinal surface**, particularly the lower part, but has no direct relation to the right lung.

Q: Which airway structure enters the lung at the hilum?

Primary/Principal bronchus. ***Primary/Principal bronchus*** - The **primary/principal bronchus** (main bronchus) is the largest airway structure that enters each lung at the **hilum** [2]. - It then divides into secondary bronchi within the lung lobes. *Secondary bronchus* - **Secondary bronchi** (lobar bronchi) branch off from the primary bronchi *after* the primary bronchus has already entered the lung. - They supply the individual **lobes** of the lung. *Tertiary bronchus* - **Tertiary bronchi** (segmental bronchi) are further divisions of the secondary bronchi. - They supply the **bronchopulmonary segments**, which are smaller functional units within the lung lobes. *Bronchiole* - **Bronchioles** are smaller airway passages that branch from the tertiary bronchi and lack cartilage [1]. - They are located deeper within the lung tissue, well past the hilum.

Q: The internal thoracic artery is a branch of which vessel?

Subclavian artery. Subclavian artery - The internal thoracic artery (also known as the internal mammary artery) is a direct branch of the first part of the subclavian artery. - It descends into the chest and supplies the anterior chest wall, breasts, and contributes to the supply of the diaphragm. Arch of aorta - The arch of the aorta gives off major branches such as the brachiocephalic trunk, left common carotid artery, and left subclavian artery. - While the subclavian artery originates from the arch (or the brachiocephalic trunk on the right), the internal thoracic artery is a more distal branch off the subclavian itself, not directly off the arch. Superior epigastric artery - The superior epigastric artery is actually one of the two terminal branches of the internal thoracic artery, indicating it is a distal continuation, not its origin [1]. - It descends into the rectus sheath to anastomose with the inferior epigastric artery [1]. Thyrocervical trunk - The thyrocervical trunk is a short, thick artery that arises from the first part of the subclavian artery. - Its branches (inferior thyroid, superficial cervical, and suprascapular arteries) primarily supply structures in the neck and shoulder, not the internal thoracic artery.

Question 1

The aortic hiatus is formed by the right and left crura of the diaphragm. Which of the following structures does NOT pass through the aortic hiatus?

Accepted Answer

Left gastric vein

Answer

Thoracic duct

Answer

Left vagus nerve

Answer

Azygos vein

Question 2

Which of the following statements about the hemiazygos vein is incorrect?

Accepted Answer

Formed by right lumbar azygos and right ascending lumbar veins

Answer

Does not pierce the left crus of diaphragm

Answer

Does not drain the esophageal vein directly

Answer

At T9 level drains into azygos vein

Question 3

The ventral surface of the adult heart, as seen on gross examination or radiography, is comprised primarily of the

Accepted Answer

Right ventricle

Answer

Left atrium

Answer

Left ventricle

Answer

Inferior vena cava

Question 4

Which of the following structures anchors the breast tissue to the overlying skin?

Accepted Answer

Cooper's ligaments

Answer

Cruciate ligaments

Answer

Falciform ligament

Answer

Pectoralis major fascia

Question 5

The root of the right lung does not lie behind which one of the following?

Accepted Answer

Right vagus

Answer

Superior vena cava

Answer

Right atrium

Answer

Phrenic nerve

Question 6

Which myocardial region is most likely to experience ischemia following occlusion of the left anterior descending artery?

Accepted Answer

Anterior wall

Answer

Left atrium

Answer

Right ventricle

Answer

Interatrial septum

Question 7

Which of the following is an anterior mediastinal tumor?

Accepted Answer

Thymoma

Answer

Lymphoma

Answer

Aortic aneurysm

Answer

Bronchogenic cyst

Question 8

Which of the following is related to the mediastinal part of the right lung?

Accepted Answer

SVC

Answer

Arch of aorta

Answer

Pulmonary trunk

Answer

Left atrium

Question 9

Which airway structure enters the lung at the hilum?

Accepted Answer

Primary/Principal bronchus

Answer

Secondary bronchus

Answer

Bronchiole

Answer

Tertiary bronchus

Question 10

The internal thoracic artery is a branch of which vessel?

Accepted Answer

Subclavian artery

Answer

Arch of aorta

Answer

Superior epigastric artery

Answer

Thyrocervical trunk

Thorax — MCQs

Thorax — MCQs

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