📚 Question Bank

Correct Answer: C

The right lung is larger and conventionally divided into 10 bronchopulmonary segments.

They are distributed as: 3 in the superior lobe (Apical, Posterior, Anterior), 2 in the middle lobe (Lateral, Medial), and 5 in the inferior lobe (Superior, and four basal segments). The left lung typically has 8 to 10 segments due to the fusion of some segmental bronchi.

Correct Answer: B

The arrangement of structures in the hilum differs between the right and left sides.

Using the RALS mnemonic (Right Anterior, Left Superior), we know that in the left hilum, the pulmonary artery loops up and sits superior to the left main bronchus. In the right hilum, the pulmonary artery sits anteriorly, and the eparterial bronchus is the most superior structure.

Correct Answer: D

We know objects favor the right main bronchus because it is wider and more vertical.

Once inside the right bronchus, gravity dictates the path. If the patient is sitting or standing upright, the object will fall straight down into the lowest possible point, which is the posterior basal segment of the inferior lobe. (If they were lying flat on their back, it would drop into the superior segment of the inferior lobe).

Correct Answer: C

Just as the azygos vein arches over the right hilum, the left lung has its own massive cardiovascular neighbor.

The arch of the aorta loops directly over the root of the left lung and continues downward as the descending thoracic aorta, leaving a deep, continuous, curved impression along the entire medial surface of the left lung.

Correct Answer: B

This is a unique anatomical quirk of the right side.

The right main bronchus gives off its branch to the upper lobe very early. Because this superior lobar bronchus sits on top of (superior to) the right pulmonary artery at the hilum, it is named the eparterial bronchus ('epi' = upon/above, 'arterial' = the artery). The rest of the bronchi on the right and all bronchi on the left pass below the artery and are termed hyparterial.

Correct Answer: B

This is the fundamental basis of lung surgery!

The pulmonary arteries and the bronchi act like a tree trunk, running exactly together directly into the center of each bronchopulmonary segment. The pulmonary veins, however, do not follow the airways. They run along the borders between the segments (intersegmental septa), draining adjacent segments simultaneously.

Correct Answer: B

The apex of the lung extends above the first rib into the root of the neck.

Arching directly over this pleural dome is the subclavian artery (along with the lower trunk of the brachial plexus). A tumor growing at the very top of the lung (Pancoast tumor) can easily compress this artery, leading to diminished pulses and ischemia in the affected arm.

Correct Answer: B

The lungs have a deep and a superficial lymphatic system.

The superficial plexus lies just under the visceral pleura and drains inward toward the hilum. Both the deep and superficial systems converge and drain primarily into the bronchopulmonary nodes, which are situated exactly at the hilum (root) of the lung. From there, lymph moves up to the tracheobronchial nodes.

Correct Answer: C

The bronchial arteries supply oxygenated blood to the lung stroma.

Typically, there are two left bronchial arteries, and they arise directly from the anterior aspect of the descending thoracic aorta. (The right side is more variable; there is usually only one right bronchial artery, and it often branches off a posterior intercostal artery).

Correct Answer: B

The alveoli are lined mostly by flat Type I cells for gas exchange.

However, scattered among them are cuboidal Type II pneumocytes. Their critical job is to secrete pulmonary surfactant, a complex mixture of lipids and proteins. Surfactant coats the inside of the alveolus and drastically reduces surface tension, preventing the delicate air sacs from collapsing entirely when you exhale.

Correct Answer: C

As lymph drains upward from the hila of the lungs, it passes through nodes situated around the trachea and bronchi.

The nodes tucked directly into the inferior angle of the tracheal bifurcation (right under the carina) are called the inferior tracheobronchial nodes or subcarinal nodes. Enlargement of these nodes can physically widen the angle of the carina, a sign visible on bronchoscopy.

Correct Answer: B

The esophagus travels straight down the posterior mediastinum, slightly to the right of the midline.

Therefore, it leaves a distinct vertical groove on the medial surface of the right lung, located entirely posterior to the hilum and the pulmonary ligament. (On the left lung, the descending aorta occupies this posterior position).

Correct Answer: B

Remember that gravity dictates where aspirated fluids go. The fluid will enter the wider, more vertical right main bronchus.

If the patient is lying flat on their back (supine), gravity pulls the fluid down the posterior wall of the airway. The very first branch that shoots backward off the bronchial tree is the bronchus supplying the superior segment of the right inferior lobe, making it the prime target for supine aspiration.

Correct Answer: C

When you take a breath in, your chest cavity creates a strong negative pressure (a vacuum) to pull air downward.

Without rigid structural support, this vacuum would simply suck the flexible airways completely shut (like sucking too hard on a flimsy plastic straw). The C-shaped hyaline cartilage rings act as a rigid skeleton to keep the airway patent (open) against this collapsing pressure.

Correct Answer: B

The transverse thoracic plane is one of the most important landmarks in the human body.

It is an imaginary flat line drawn from the sternal angle (Angle of Louis) in the front to the intervertebral disc between the T4 and T5 vertebrae in the back. This plane neatly divides the mediastinum into the superior mediastinum above it and the inferior mediastinum below it.

Correct Answer: C

The inferior mediastinum is split into three parts by the pericardial sac.

• The anterior mediastinum is in front of the pericardium.
• The middle mediastinum is the pericardial sac and everything inside it, primarily the heart and the roots of the great vessels.
• The posterior mediastinum is behind the pericardium.

Correct Answer: B

The thymus is a primary lymphoid organ where T-cells mature.

In infants and children, it is a massive, bi-lobed gland sitting immediately posterior to the manubrium. However, after puberty, it undergoes gradual involution (shrinking) and is mostly replaced by adipose (fat) tissue in adults, leaving only small glandular remnants.

Correct Answer: B

The venous drainage of the head, neck, and upper limbs converges in the superior mediastinum.

The internal jugular and subclavian veins merge to form the brachiocephalic veins. The right and left brachiocephalic veins then unite behind the right 1st costal cartilage to form the massive Superior Vena Cava (SVC), which drops straight down into the right atrium.

Correct Answer: B

The esophagus is a long, vertical tube that stays relatively close to the spine.

It begins in the neck, enters the thorax through the thoracic inlet into the superior mediastinum (sitting directly behind the trachea). It then passes down behind the transverse thoracic plane to enter the posterior mediastinum (sitting directly behind the pericardium) before piercing the diaphragm.

Correct Answer: C

The phrenic nerve (C3, C4, C5) is the dedicated nerve of the diaphragm.

It enters the superior mediastinum and travels virtually straight down, passing anterior to the lung roots and running perfectly along the sides of the pericardial sac (in the middle mediastinum) to reach the diaphragm.

Correct Answer: D

The thoracic duct is the major lymphatic highway of the body.

It carries chyle (lymph mixed with emulsified fats) from the entire lower half of the body and the left upper half of the body. It ascends through the posterior and superior mediastinum, lying between the descending aorta and the azygos vein, before emptying into the left venous angle.

Correct Answer: C

The aortic arch typically gives off three major branches to supply the head, neck, and upper limbs.

From right to left (the direction of blood flow), the first and largest branch is the brachiocephalic trunk (which soon splits into the right subclavian and right common carotid). This is followed by the left common carotid, and finally the left subclavian artery.

Correct Answer: C

The anterior mediastinum is the smallest compartment, forming a narrow slit between the sternum and the pericardium.

It does not contain any major organs or large vessels. It mostly houses fat, loose connective tissue, lymph nodes, and the sternopericardial ligaments (which physically anchor the pericardial sac to the back of the sternum).

Correct Answer: C

The trachea travels down through the superior mediastinum and terminates exactly at the transverse thoracic plane (T4/T5 level).

The internal, keel-shaped cartilage ridge at this point of division is called the carina. It is a highly sensitive landmark heavily supplied by sensory nerve endings to trigger the cough reflex.

Correct Answer: A

Visualizing the layers of the superior mediastinum is crucial for surgical approaches.

From front to back (anterior to posterior):
1. Veins (Brachiocephalic veins and SVC)
2. Arteries (Aortic arch and its branches)
3. Respiratory tube (Trachea)
4. Digestive tube (Esophagus) resting against the spine.