A bullet enters the left lung and collapses it. Which cavity has been entered?

• A. Pleural cavity
• B. Abdominal cavity
• C. Cranial cavity
• D. Pericardial cavity

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by identifying the anatomical location of the injury. The problem states that the bullet enters the left lung, which is part of the thoracic cavity.
2. Step 2: Recall that the lungs are surrounded by a specific cavity called the pleural cavity. This cavity is a thin space between the two layers of the pleura (the visceral pleura and the parietal pleura) that encase the lungs.
3. Step 3: Understand the function of the pleural cavity. It contains a small amount of fluid that reduces friction during breathing and helps maintain lung expansion.
4. Step 4: Eliminate the other options based on their anatomical locations and functions: The abdominal cavity houses organs like the stomach and intestines, the cranial cavity contains the brain, and the pericardial cavity surrounds the heart.
5. Step 5: Conclude that the cavity entered by the bullet is the pleural cavity, as it directly surrounds the lungs and is affected when the lung collapses.