Thorax Practice Questions

Q: Which of the following statements is false about the right bronchus?

More horizontal. ***More horizontal*** - The right bronchus is traditionally described as **more vertical** or **more directly in line with the trachea** compared to the left bronchus. - This anatomical orientation makes it more susceptible to the aspiration of foreign bodies. *Shorter* - The **right main bronchus** is indeed shorter than the left main bronchus. - Its length is typically 2-3 cm, while the left main bronchus is about 5 cm long. *Wider* - The **right main bronchus** has a larger diameter than the left main bronchus. - This wider lumen contributes to the ease with which foreign bodies can enter it. *In the line of trachea* - The right main bronchus diverges from the trachea at a **less acute angle** (approximately 25 degrees) compared to the left (approximately 45 degrees). - This makes it appear more as a **direct continuation of the trachea**, facilitating aspiration into the right lung.

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: 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: 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 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: 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: 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: Which structures are located anterior to the transverse sinus?

Aorta. ***Aorta*** - The **transverse sinus of the pericardium** is a passage within the pericardial cavity that separates the great arteries (aorta and pulmonary trunk) anteriorly from the atria and great veins posteriorly. - The **ascending aorta** and **pulmonary trunk** are both located anterior to the transverse sinus. - This anatomical relationship is clinically important during cardiac surgery, as the transverse sinus can be used to pass ligatures around the great vessels. *Right atrium* - The **right atrium** is located posterior to the transverse sinus. - It forms part of the posterior wall of the pericardial cavity and receives the superior and inferior venae cavae. - The transverse sinus separates the atria from the anteriorly positioned great arteries. *Left atrium* - The **left atrium** is also positioned posterior to the transverse sinus. - It forms the base of the heart and receives the pulmonary veins. - Like the right atrium, it lies behind the plane of the transverse sinus. *Right pulmonary artery* - The **right pulmonary artery** is a branch of the pulmonary trunk that passes to the right lung. - While the **pulmonary trunk** itself is anterior to the transverse sinus, the **right pulmonary artery** branch courses laterally and posteriorly, passing behind the ascending aorta and superior vena cava. - Therefore, the right pulmonary artery is NOT considered anterior to the transverse sinus in the same way the main great vessels (aorta and pulmonary trunk) are.

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].

Question 1

Which of the following statements is false about the right bronchus?

Accepted Answer

More horizontal

Answer

Shorter

Answer

In the line of trachea

Answer

Wider

Question 2

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 3

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 4

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 5

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 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

Azygos vein drains into:

Accepted Answer

Superior vena cava

Answer

Left brachiocephalic vein

Answer

Inferior vena cava

Answer

Right brachiocephalic vein

Question 9

Which structures are located anterior to the transverse sinus?

Accepted Answer

Aorta

Answer

Right atrium

Answer

Left atrium

Answer

Right pulmonary artery

Question 10

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

Thorax — MCQs

Thorax — MCQs

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