Which structure separates the thoracic cavity from the abdominopelvic cavity?

• A. Pleural Cavities
• B. Abdominal Cavity
• C. Pelvic Cavity
• D. Diaphragm

Answer: (D)

The diaphragm is the muscular partition that forms the boundary between the thoracic cavity and the abdominopelvic cavity. It sits as a dome-shaped sheet between the lungs and heart above and the digestive organs below, effectively separating the air-filled chest from the abdominal contents. The thoracic cavity houses the heart and lungs, while the abdominopelvic cavity contains most of the digestive organs and other viscera; the diaphragm’s inferior surface marks the division between these two regions. In contrast, the pleural cavities are spaces within the thorax around the lungs and do not separate the thorax from the abdomen, and the abdominal and pelvic cavities are parts of the same abdominopelvic cavity, not divided by a structure.