📚 Question Bank

Correct Answer: C

The parietal pleura is stuck to the chest wall, so it simply shares the blood supply of the chest wall.

The intercostal arteries supply the lateral and posterior costal pleura, while the internal thoracic arteries supply the anterior aspect.

Correct Answer: B

While the massive pulmonary arteries carry deoxygenated blood to the lungs for gas exchange, they do not feed the lung tissue itself.

The actual living tissue of the lungs and the visceral pleura are supplied with oxygenated blood by the bronchial arteries, which arise directly from the descending thoracic aorta.

Correct Answer: C

The lungs do not completely fill the pleural cavity during quiet breathing. The empty gutters at the lowest edges are called recesses.

The costodiaphragmatic recess is a deep, circular trench where the costal pleura meets the diaphragmatic pleura. Because it is the lowest point in the thorax, gravity causes effusions or blood to pool here first, blunting the costophrenic angles on an X-ray.

Correct Answer: C

The costomediastinal recess is located anteriorly, where the costal pleura folds sharply to become the mediastinal pleura.

It is much larger on the left side because the left lung has a large cutout (the cardiac notch) to make room for the heart. During deep inspiration, the lingula of the left lung expands into this empty recess.

Correct Answer: D

This is a classic anatomical trick regarding referred pain.

The central portion of the diaphragmatic pleura (and the adjacent mediastinal pleura) is innervated by the phrenic nerve (C3-C5). The skin over the shoulder is supplied by the supraclavicular nerves (also C3-C4). When the central diaphragm is irritated, the brain misinterprets the origin of the signal and refers the pain to the shoulder tip.

Correct Answer: C

Unlike the central portion, the peripheral rim of the diaphragmatic pleura is innervated by the sensory branches of the lower six intercostal nerves and the subcostal nerve.

Because these same nerves continue downward to supply the skin and muscles of the abdomen, inflammation at the edge of the diaphragm often presents as sharp pain in the anterolateral abdominal wall, sometimes mimicking appendicitis or cholecystitis.

Correct Answer: B

The phrenic nerve takes a long vertical journey through the thorax. As it travels down to the diaphragm, it is sandwiched directly between the pericardium and the mediastinal pleura.

Along the way, it provides somatic sensory fibers to both the fibrous pericardium and the mediastinal pleura. Therefore, irritation here also refers pain to the shoulder.

Correct Answer: C

You must know the pleural borders! In the midaxillary line during expiration:

• The inferior border of the lung is at the 8th rib.
• The inferior border of the parietal pleura is at the 10th rib.

Correct Answer: B

The rule of 2s is helpful here. The inferior border of the lung is always roughly two ribs higher than the inferior reflection of the pleura.

• Midclavicular line: Lung at Rib 6, Pleura at Rib 8
• Midaxillary line: Lung at Rib 8, Pleura at Rib 10
• Scapular/Paravertebral line: Lung at Rib 10, Pleura at Rib 12

Correct Answer: C

A tension pneumothorax is a critical emergency. A tear in the lung acts as a one-way flutter valve.

Every time the patient breathes in, air is sucked into the pleural cavity. When they breathe out, the tissue flap closes, trapping the air. With each breath, the pressure in the pleural cavity rises drastically, collapsing the lung and physically pushing the entire mediastinum (and heart) to the opposite side, cutting off venous return.

Correct Answer: C

As established by the surface anatomy rules (6/8, 8/10, 10/12), the inferior border of the lung rests approximately two rib spaces higher than the absolute lowest limit of the parietal pleural sac during quiet expiration.

This two-rib gap is what forms the costodiaphragmatic recess, the safe zone for tapping fluid.

Correct Answer: C

If you are dissecting from the inside of the lung cavity outward, the first layer you pass through is the paper-thin parietal pleura. Immediately outside of that is the loose connective tissue of the endothoracic fascia.

The very next layer you hit is the muscular wall of the chest—specifically, the deepest layer of muscle, which is the innermost intercostal muscles.

Correct Answer: C

While a massive central injury to the aorta or pulmonary trunk will certainly cause a hemothorax, the vast majority of traumatic hemothoraxes result from injuries to the chest wall.

Specifically, a knife or broken rib usually lacerates the high-pressure intercostal arteries (running under every rib) or the internal thoracic arteries (running parasternally), causing them to bleed heavily into the pleural space.

Correct Answer: B

Chyle is a milky-white fluid consisting of lymph and emulsified fats absorbed from the intestines.

It is transported upward through the thorax by the massive thoracic duct. If this duct is accidentally nicked during thoracic surgery or eroded by a lymphoma, chyle will pour out and rapidly fill the pleural cavity, creating a chylothorax.

Correct Answer: C

The neurovascular bundle (Vein, Artery, Nerve) runs in the costal groove along the inferior border of the rib.

If you slide the needle just below a rib, you risk severing the intercostal artery (causing hemorrhage) or the intercostal nerve (causing severe pain or numbness). To be safe, you always 'ride over' the top edge (superior border) of the rib below.

Correct Answer: B

Normally, the right and left parietal pleurae meet in the midline behind the sternum. However, on the left side, the pleural reflection deviates laterally between the 4th and 6th costal cartilages to accommodate the heart.

This leaves a small 'bare area' where the pericardium is in direct contact with the anterior chest wall, making it a safe window to insert a needle into the pericardium without risking a pneumothorax.

Correct Answer: C

The costomediastinal recess is the vertical potential space behind the sternum where the costal pleura transitions into the mediastinal pleura.

Because the left lung has a cardiac notch cut out of its anterior margin, this recess is unusually large on the left side. When you take a deep breath, the tongue-like projection of the left lung (the lingula) slides right into this space.

Correct Answer: C

This is a unique vascular quirk. While the visceral pleura receives arterial blood from the systemic circulation (bronchial arteries), its venous drainage largely dumps into the pulmonary veins.

This means a small amount of deoxygenated blood from the pleura mixes with the freshly oxygenated blood returning from the lungs to the left atrium, creating a minor, normal physiological right-to-left shunt.

Correct Answer: B

Lymphatics follow the blood supply.

Because the costal pleura is supplied by the intercostal and internal thoracic arteries, its lymphatic drainage flows back toward the spine into the intercostal nodes, or forward toward the sternum into the parasternal (internal thoracic) nodes. The visceral pleura, on the other hand, drains inward to the bronchopulmonary nodes at the lung root.

Correct Answer: A

The inferior limit of the parietal pleura generally follows the 12th rib posteriorly. However, medially near the spine, the pleural sac frequently drops below the medial half of the 12th rib into the costovertebral angle.

Because the upper pole of the kidney sits exactly in this region, an incision made too high in the back to access the kidney can easily breach the pleura, causing an iatrogenic pneumothorax.

Correct Answer: C

The diaphragm develops from several fused structures. The posterolateral aspects are formed by the pleuroperitoneal membranes, which separate the developing pleural and peritoneal cavities.

If this membrane fails to form or fuse completely (most commonly on the left side), a large defect remains. The intestines can herniate upward into the pleural cavity, compressing the developing lung and causing severe pulmonary hypoplasia.

Correct Answer: C

The suprapleural membrane tents over the cervical pleura to protect it as it bulges into the root of the neck.

It acts like a taught, fibrous canopy. Its outer margin is attached to the inner border of the 1st rib, and its apex is firmly anchored to the tip of the transverse process of the C7 vertebra. It is clinically considered the spreading tendon of the scalenus minimus muscle.

Correct Answer: C

This phenomenon is known as mediastinal flutter.

During inspiration, the chest cavity expands, creating negative pressure. On the injured side, air simply rushes in through the wound, so no negative pressure builds up. On the uninjured side, normal negative pressure develops, sucking the flexible mediastinum toward the normal side. During expiration, the pressure reverses, pushing the mediastinum back. This violent shifting severely compromises venous return to the heart.

Correct Answer: B

While both layers can produce and absorb fluid, the parietal pleura does the vast majority of the heavy lifting.

The parietal pleura is highly vascularized by systemic arteries and possesses numerous stomata (pores) that open directly into the robust lymphatic system of the chest wall. This allows it to rapidly clear excess fluid and proteins from the pleural space, keeping it virtually dry.

Correct Answer: B

The lining of the body cavities originates from the lateral plate mesoderm, which splits into two layers.

• The outer somatic mesoderm forms the parietal pleura (which retains somatic, sharp pain innervation).
• The inner splanchnic mesoderm wraps around the developing gut tube and lung buds to form the visceral pleura (which receives dull, autonomic innervation).