Thorax Practice Questions

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: 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**.

Q: A person inhaled a peanut two days ago and is now unable to cough it out. Where is the possible location?

Right lower lobe. ***Right lower lobe*** - Due to the **angle** of the right main bronchus, which is less acute than the left, aspirated foreign bodies, like a peanut, tend to preferentially enter the **right bronchial tree**. - Within the right lung, foreign bodies are most commonly found in the **right lower lobe** because its **bronchus is the most direct continuation** of the right main bronchus, especially in an upright position. *Right superior lobe* - While material can go into the right lung, the **right upper lobe bronchus** branches off at a more acute angle, making aspiration into this lobe less common than into the lower lobes when a person is in an upright or semi-recumbent position. - Aspiration into the superior lobes is more common with specific body positions or in cases of massive aspiration. *Right middle lobe* - The **right middle lobe bronchus** is smaller and branches off at an angle that is less favorable for direct aspiration compared to the right lower lobe. - Aspiration to this lobe is less frequent than to the lower lobes. *Left lower lobe* - The **left main bronchus** is narrower and branches off at a much more acute angle from the trachea compared to the right main bronchus. - This anatomical difference makes aspiration into the left lung, including the **left lower lobe**, significantly less common than into the right lung.

Q: The commonest site of aspiration of a foreign body in the supine position is into the:

Right lower lobe superior segment. ***Right lower lobe superior segment*** - When an individual is in the **supine position**, the most dependent portion of the lung (where gravity would pull aspirated material) is the **superior segment of the right lower lobe**. - This anatomical orientation, combined with the **wider and more vertical right main bronchus**, increases the likelihood of aspirated foreign bodies entering and settling in this specific segment. - The superior segment of the right lower lobe is **posteriorly located** and becomes the most dependent when lying supine. *Right upper lobe apical* - While the right upper lobe is on the favored side for aspiration due to the anatomy of the main bronchi, the **apical segment** is not the most dependent in the supine position. - Aspiration into the apical segment is generally less common than into more dependent segments when lying flat. *Left basal* - The **left main bronchus** is narrower and takes a more acute angle compared to the right, making aspiration into the left lung less common. - Even if aspiration were to occur in the left lung, the **basal segments** are not the most dependent in the supine position. *Right middle lobe medial segment* - The medial segment of the middle lobe is **not as posteriorly positioned** as the superior segment of the right lower lobe in the supine position. - While aspiration can occur into the middle lobe, it is **less common** than into the superior segment of the right lower lobe when supine due to the anatomical positioning and gravity effects.

Q: Azygos vein drains into:

Superior vena cava. Wait, what? Azygos vein drains into: ***Superior vena cava*** - The **azygos vein** ascends along the right side of the vertebral column and typically arches over the root of the right lung before draining into the **superior vena cava (SVC)**. - This anatomical arrangement allows the azygos system to collect venous blood from the posterior thoracic and abdominal walls, as well as the bronchi and esophagus, ultimately returning it to the systemic circulation via the SVC [1]. *Left brachiocephalic vein* - The **left brachiocephalic vein** drains blood from the upper left limb and left side of the head and neck. - It merges with the right brachiocephalic vein to form the SVC; the azygos vein does not directly drain into it. *Inferior vena cava* - The **inferior vena cava (IVC)** collects deoxygenated blood from the lower body. - The azygos system primarily drains structures above the diaphragm, distinct from the IVC's drainage area. *Right brachiocephalic vein* - The **right brachiocephalic vein** drains blood from the upper right limb and right side of the head and neck. - While it contributes to the formation of the SVC, the azygos vein's direct connection is to the SVC itself, not the right brachiocephalic vein.

Q: Sympathetic supply to the heart arises from which of the following spinal segments?

T1 to T5. The preganglionic sympathetic fibers that innervate the heart originate from the lateral horns of the thoracic spinal segments T1 to T5. These fibers synapse in the cervical and upper thoracic sympathetic ganglia, from which postganglionic fibers extend to the heart. While there is some overlap, the primary and most significant sympathetic innervation to the heart stems predominantly from T1 to T5, making T2 to T6 a less precise answer. Including T6 would extend past the typical primary cardiac sympathetic innervation, which largely concludes at T5. This range is too caudal and largely beyond the principal segments providing sympathetic innervation to the heart. Segments T6-T8 are more involved in sympathetic supply to abdominal organs and other structures rather than direct cardiac control.

Q: The thoracic duct crosses from the right to the left at the level of

T4-T5 vertebra. ***T4-T5 vertebra*** - The **thoracic duct** crosses from the right to the left side of the vertebral column at the level of the **T4-T5 vertebrae**, specifically just above the root of the left lung. - This crossover is an important anatomical landmark as it signifies the duct's ascent towards the neck to drain into the left subclavian vein. *T12 vertebra* - The **thoracic duct** originates from the **cisterna chyli** at the level of the L1 or L2 vertebra and ascends into the thorax at or below the T12 vertebra, it does not cross over at this level. - This level primarily marks its entry into the thoracic cavity, not its main crossover point. *T6 vertebra* - While the **thoracic duct** is present in the thorax at this level, it does not undergo its characteristic crossover from right to left at the T6 vertebra. - The duct continues its ascent along the right side of the vertebral column before moving across. *T2 vertebra* - By the level of the T2 vertebra, the **thoracic duct** has already crossed to the left side of the vertebral column and is ascending towards its termination in the neck. - The crossover event occurs more inferiorly, at the T4-T5 level.

Q: Which of the following is not a boundary of Koch's triangle?

Limbus fossa ovalis. ***Limbus fossa ovalis*** - The **limbus fossa ovalis** is a prominent oval ridge on the **interatrial septum** that surrounds the fossa ovalis. - It is **not involved** in forming the boundaries of Koch's triangle, which is located in the **right atrium** near the AV node [1]. *Tricuspid valve ring* - The **tricuspid valve ring** (or annulus) forms one of the key anatomical boundaries of **Koch's triangle**, specifically its base [1]. - This **fibrous ring** anchors the tricuspid valve leaflets and marks the inferior aspect of the triangle [1]. *Coronary sinus* - The **coronary sinus ostium** (opening) forms another crucial boundary of **Koch's triangle** [1]. - It is located at the **inferior-posterior aspect** of the interatrial septum, opening into the right atrium [1]. *Tendon of todaro* - The **Tendon of Todaro** is a fibrous structure that forms the superior boundary of **Koch's triangle** [1]. - It extends from the **Eustachian valve** (of the inferior vena cava) towards the central fibrous body, playing a role in **AV nodal localization** [1].

Q: The right coronary artery supplies blood to all of the following structures, except?

Anterior 2/3 of ventricular septum. ***Anterior 2/3 of ventricular septum*** - The **anterior two-thirds of the interventricular septum** is primarily supplied by the **septal branches of the left anterior descending artery** (LAD) [1], a branch of the left coronary artery. - Therefore, the right coronary artery does not typically supply this region. *SA node* - The **SA node** (sinoatrial node) is the heart's natural pacemaker and receives its blood supply from the **right coronary artery** in about 60% of individuals. - Occlusion of the RCA can lead to symptomatic **bradycardia** or **SA node dysfunction**. *AV node* - The **AV node** (atrioventricular node), crucial for coordinating ventricular contraction, is supplied by the **right coronary artery** in approximately 90% of individuals [1]. - Infarcts in the RCA territory can manifest as various degrees of **heart block**. *Posterior wall of left ventricle* - The **posterior wall of the left ventricle** is predominantly supplied by the **posterior descending artery (PDA)**, which in about 80% of people, is a terminal branch of the **right coronary artery** [1]. - This supply is vital for the contractile function of the left ventricle's posterior aspect.

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

Great cardiac vein. ***Great cardiac vein*** - The **great cardiac vein** is a major tributary that drains into the **coronary sinus**, carrying deoxygenated blood from the anterior and left ventricular walls [1]. - It travels alongside the **anterior interventricular artery** (LAD) and then wraps around the left side of the heart to join the coronary sinus [1]. *Anterior cardiac vein* - The **anterior cardiac veins** typically collect blood directly into the **right atrium**, bypassing the coronary sinus [1]. - They primarily drain the anterior wall of the right ventricle. *Thebesian vein* - **Thebesian veins** (or venae cordis minimae) are small veins that drain blood from the **myocardium directly into the heart chambers**, predominantly the atria [1]. - They represent a direct communication between the myocardial capillaries and the heart chambers, not tributaries of the coronary sinus. *Smallest cardiac vein* - The term "smallest cardiac vein" is often used synonymously with **Thebesian veins** [1]. - These veins empty directly into the **heart chambers**, serving as an ancillary drainage system, rather than converging into the coronary sinus.

Question 1

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 2

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

Accepted Answer

Right ventricle

Answer

Left ventricle

Answer

Right atrium

Answer

Left atrium

Question 3

A person inhaled a peanut two days ago and is now unable to cough it out. Where is the possible location?

Accepted Answer

Right lower lobe

Answer

Right superior lobe

Answer

Left lower lobe

Answer

Right middle lobe

Question 4

The commonest site of aspiration of a foreign body in the supine position is into the:

Accepted Answer

Right lower lobe superior segment

Answer

Right upper lobe apical

Answer

Left basal

Answer

Right middle lobe medial segment

Question 5

Azygos vein drains into:

Accepted Answer

Superior vena cava

Answer

Left brachiocephalic vein

Answer

Inferior vena cava

Answer

Right brachiocephalic vein

Question 6

Sympathetic supply to the heart arises from which of the following spinal segments?

Accepted Answer

T1 to T5

Answer

T2 to T6

Answer

T3 to T7

Answer

T4 to T8

Question 7

The thoracic duct crosses from the right to the left at the level of

Accepted Answer

T4-T5 vertebra

Answer

T12 vertebra

Answer

T2 vertebra

Answer

T6 vertebra

Question 8

Which of the following is not a boundary of Koch's triangle?

Accepted Answer

Limbus fossa ovalis

Answer

Tricuspid valve ring

Answer

Coronary sinus

Answer

Tendon of Todaro

Question 9

The right coronary artery supplies blood to all of the following structures, except?

Accepted Answer

Anterior 2/3 of ventricular septum

Answer

Posterior wall of left ventricle

Answer

SA node

Answer

AV node

Question 10

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

Accepted Answer

Great cardiac vein

Answer

Anterior cardiac vein

Answer

Smallest cardiac vein

Answer

Thebesian vein

Thorax — MCQs

Thorax — MCQs

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