Thorax Practice Questions

Q: Which of the following is the MAJOR tributary of the coronary sinus?

Great cardiac vein. ***Great cardiac vein*** - The **great cardiac vein** is the largest and most significant tributary, draining areas supplied by the **left main coronary artery** and its branches. - It runs in the **anterior interventricular groove**, accompanying the anterior interventricular artery, and then curves around the left side of the heart to empty into the coronary sinus. *Anterior cardiac vein* - The **anterior cardiac veins** typically drain directly into the **right atrium**, bypassing the coronary sinus [1]. - They primarily drain the anterior surface of the **right ventricle**. *Thebesian vein* - The **Thebesian veins** (venae cordis minimae) are small veins that open directly into the **chambers of the heart**, not the coronary sinus. - They are responsible for a small amount of **physiological shunt** of deoxygenated blood into the left heart chambers. *Oblique vein of Marshall* - The **oblique vein of Marshall** (oblique vein of the left atrium) is a small vein originating from the posterior wall of the left atrium. - It is a **remnant of the left superior vena cava** and empties into the left extremity of the coronary sinus, but it is not considered the major tributary in terms of blood flow volume.

Q: Azygos vein drains into:

Superior vena cava. ***Superior vena cava*** - The **azygos vein** is a major venous channel that drains the walls of the thorax and abdomen, emptying directly into the **superior vena cava (SVC)**. [1] - This connection is crucial for venous return from the posterior thoracic wall, pericardium, and bronchi, especially bypassing the inferior vena cava if it's obstructed. [1] *Right subcostal vein* - The right subcostal vein is a tributary that helps form the **azygos vein**; it does not receive drainage from the azygos vein. - It contributes to the initial formation of the azygos system, not its termination. *Brachiocephalic* - The **brachiocephalic veins** are formed by the union of the internal jugular and subclavian veins, and they merge to form the **superior vena cava**. - The azygos vein drains into the superior vena cava, not directly into the brachiocephalic veins. *Right ascending lumbar vein* - The **right ascending lumbar vein** is a major tributary that contributes to the formation of the **azygos vein** in the lumbar region. - It drains into the azygos system, illustrating its origin rather than its termination.

Q: What is the average number of lobes in a human breast?

15. ***15*** - Historically, the human breast was described as containing **15 to 20 lobes**, each being a functionally distinct unit for milk production arranged radially around the nipple [1]. - This was the accepted anatomical teaching at the time of this examination. - **Note:** Modern imaging studies (MRI, ultrasound) have since shown that breasts typically contain **7-10 ductal systems/lobes** rather than 15-20, representing an important update to classical anatomy teaching. *5* - This number is too low and does not represent either the classical (15-20) or modern (7-10) understanding of breast lobe anatomy. - Insufficient to account for the complexity of the mammary ductal system. *10* - This represents the **upper range of modern anatomical understanding** (7-10 lobes based on current imaging studies). - While anatomically accurate by today's standards, the classical teaching referenced in this examination specified 15-20 lobes as average. *20* - Represents the **upper limit** of the classical range (15-20 lobes) [1]. - While within the historical normal range, **15 is considered the more typical average** in classical anatomy texts. - Modern research indicates this number significantly overestimates the actual lobe count.

Q: Which chamber of the heart forms the posterior surface?

Left Atrium (LA). ***Left Atrium (LA)*** - The **left atrium** forms the posterior surface of the heart, lying in front of the esophagus and thoracic aorta [1]. - Its posterior position makes it susceptible to enlargement, which can compress the **esophagus** and cause dysphagia [1]. *Right Atrium (RA)* - The **right atrium** primarily forms the right border of the heart and receives deoxygenated blood from the systemic circulation. - It lies anteriorly and to the right, behind the sternum and costal cartilages. *Left Ventricle (LV)* - The **left ventricle** forms the apex of the heart and part of the left border. - It is positioned *inferiorly* and *anteriorly*, contributing significantly to the *diaphragmatic surface* of the heart. *Right Ventricle (RV)* - The **right ventricle** forms the majority of the anterior surface of the heart, directly behind the sternum. - It also contributes to the *inferior surface* of the heart, resting on the diaphragm.

Q: Which part of the heart is located in the anterosuperior sternal region?

Right ventricle.. ***Right ventricle*** - The **right ventricle** forms the **most anterior part of the heart**, located directly behind the sternum and costal cartilages [1]. - Its position explains why **sternal precordial leads** (e.g., V1, V2) on an ECG primarily reflect right ventricular activity [1]. *Right atrium and auricle* - While part of the right atrium is anterior, the **right ventricle is significantly more anterior** and occupies the majority of the anterosuperior sternal region [1]. - The **right auricle** is a small, anterior appendage, but the broader chamber occupying this region is the ventricle [1]. *Left atrium* - The **left atrium** is the **most posterior chamber of the heart**, forming the base [1]. - It lies near the esophagus, making it susceptible to compression by an enlarged left atrium. *Left ventricle* - The **left ventricle** forms the **apex of the heart** and is located primarily on the **left and inferior** aspects. - It is not the most anterior structure; the right ventricle is positioned anteriorly to it [1].

Q: Which of the following statements about the mammary gland is false?

Nipple is supplied by 6th intercostal nerve. ***Nipple is supplied by 6th intercostal nerve*** - The **nipple and areola** are primarily supplied by branches of the **4th intercostal nerve**. - The 6th intercostal nerve supplies the lower part of the breast and is not the primary innervation for the nipple. *Is a modified sweat gland* - The mammary gland, or breast, is indeed a **modified apocrine sweat gland**. - This embryological origin explains its glandular structure and function of milk production. *Extends from 2nd to 6th rib vertically* - The vertical extent of the mammary gland typically ranges from the **2nd to the 6th rib**. - This anatomical positioning is consistent with its location on the anterior thoracic wall. *Supplied by internal mammary artery* - The **internal mammary artery (internal thoracic artery)** is a major blood supply to the medial aspect of the breast [2]. - Other significant arteries include the lateral thoracic and thoracoacromial arteries for the lateral aspect. The mammary gland is embedded in subcutaneous fat, although fat is absent beneath the nipple and areola [1]. Mature resting breasts lie between the skin and the pectoralis major muscle, supported by Cooper's ligaments [3].

Q: Esophagus is present in which mediastinum?

Posterior. ***Posterior*** - The **esophagus** is primarily located in the **posterior mediastinum**, where the bulk of its length (from T4/T5 to T10) traverses [2]. - It lies **posterior** to the **trachea** and **heart**, anterior to the vertebral column [2]. - For examination purposes, the esophagus is considered a **key structure of the posterior mediastinum** [2]. - Note: The uppermost part (cervical and upper thoracic) does pass through the superior mediastinum, but the majority lies in the posterior compartment. *Anterior* - The **anterior mediastinum** is a small space located between the **sternum** and the pericardium. - It primarily contains **connective tissue**, remnants of the thymus, lymph nodes, and the internal thoracic vessels [1]. - The esophagus does not traverse this compartment. *Middle* - The **middle mediastinum** is centrally located and prominently contains the **heart** and the roots of the great vessels [1]. - It also houses the **pericardium**, the main bronchi, and the phrenic nerves [1]. - The esophagus passes **posterior** to this compartment, not through it. *Superior* - The **superior mediastinum** extends from the thoracic inlet to the level of the sternal angle (T4/T5). - It contains large vessels like the **aortic arch** and its branches, the SVC, trachea, and thymus [1]. - While the **uppermost part of the thoracic esophagus** does pass through the superior mediastinum, this represents only a small portion of its total length.

Q: Which mediastinal compartment does not contain the esophagus?

Anterior mediastinum. ***Anterior mediastinum*** - The **anterior mediastinum** is the smallest subdivision of the inferior mediastinum, located between the body of the sternum and the pericardium. - It primarily contains **loose connective tissue, lymph nodes, and the thymus remnant** [1]. - The esophagus is **never found** in the anterior mediastinum, making this the most definitive correct answer. *Middle mediastinum* - The **middle mediastinum** contains the pericardium and heart, along with the roots of the great vessels [1]. - The esophagus is **not contained within** the middle mediastinum proper; however, it lies immediately posterior to it in the posterior mediastinum. - Note: While technically the middle mediastinum does not contain the esophagus, the **anterior mediastinum** is the most definitive answer as it is furthest removed from the esophagus. *Posterior mediastinum* - The **posterior mediastinum** is located posterior to the pericardium and diaphragm, and anterior to the thoracic vertebrae. - It **contains the esophagus**, along with the thoracic aorta, azygos vein, hemiazygos vein, and thoracic duct. *Superior mediastinum* - The **superior mediastinum** extends from the thoracic inlet to the level of the sternal angle (T4-T5 level). - The **esophagus traverses** through the superior mediastinum as it descends from the neck towards the abdomen.

Q: Which chamber of the heart is located anterior to the sternum?

Right ventricle. ***Right ventricle*** - The **right ventricle** forms the majority of the **anterior surface of the heart** and is the chamber closest to the sternum [2]. - This anatomical position is important clinically, for instance, in cases of **pericardial effusion** or **chest trauma**. *Left atrium* - The **left atrium** is located most **posteriorly** in the heart, adjacent to the esophagus [1], [2]. - Due to its posterior position, an enlarged left atrium can compress the esophagus, causing **dysphagia**. *Left ventricle* - The **left ventricle** forms the **apex of the heart** and is located more on the left and posterior aspect compared to the right ventricle [2]. - While it contributes to the anterior surface, the **right ventricle** is more directly anterior to the sternum [2]. *Right atrium* - The **right atrium** is positioned to the right and slightly posterior to the right ventricle. - It receives venous blood from the body and forms the **right border of the heart**.

Question 1

Which of the following is the MAJOR tributary of the coronary sinus?

Accepted Answer

Great cardiac vein

Answer

Anterior cardiac vein

Answer

Thebesian vein

Answer

Oblique vein of Marshall

Question 2

Azygos vein drains into:

Accepted Answer

Superior vena cava

Answer

Right subcostal vein

Answer

Right ascending lumbar vein

Answer

Brachiocephalic

Question 3

Which of the following statements about the anatomy of the right ventricle is correct?

Accepted Answer

The crista supraventricularis separates the tricuspid and pulmonary valves, and the apex is trabeculated

Answer

TV & PV Share fibrous continuity

Answer

More prominent trabeculation

Answer

All of the options

Question 4

What is the average number of lobes in a human breast?

Accepted Answer

15

Answer

5

Answer

10

Answer

20

Question 5

Which chamber of the heart forms the posterior surface?

Accepted Answer

Left Atrium (LA)

Answer

Right Atrium (RA)

Answer

Left Ventricle (LV)

Answer

Right Ventricle (RV)

Question 6

Which part of the heart is located in the anterosuperior sternal region?

Accepted Answer

Right ventricle.

Answer

Right atrium and auricle.

Answer

Left atrium.

Answer

Left ventricle.

Question 7

Which of the following statements about the mammary gland is false?

Accepted Answer

Nipple is supplied by 6th intercostal nerve

Answer

Is a modified sweat gland

Answer

Extends from 2nd to 6th rib vertically

Answer

Supplied by internal mammary artery

Question 8

Esophagus is present in which mediastinum?

Accepted Answer

Posterior

Answer

Answer

Middle

Answer

Superior

Question 9

Which mediastinal compartment does not contain the esophagus?

Accepted Answer

Anterior mediastinum

Answer

Posterior mediastinum

Answer

Middle mediastinum

Answer

Superior mediastinum

Question 10

Which chamber of the heart is located anterior to the sternum?

Accepted Answer

Right ventricle

Answer

Left ventricle

Answer

Right atrium

Answer

Left atrium

Thorax — MCQs

Thorax — MCQs

On this page

Practice by Chapter

Want unlimited practice?