Which structure lies between the thoracic and abdominal cavities?

Question

Quizplus · Accepted Answer

The diaphragm is a thin muscle that separates the abdominal cavity from the thoracic cavity and is a vital structure when it comes to breathing. When you inhale, the diaphragm contracts, which enlarges the chest cavity and draws air into the lungs. When you exhale, the diaphragm relaxes and the air is pushed out of the lungs.
The mediastinum is the area in the chest between the lungs that contains the heart, part of the windpipe (the trachea), the esophagus, the ascending aorta (the large artery which carries blood from the left ventricle of the heart on its way to the rest of the body) and right and left pulmonary arteries. It is located in the thoracic cavity but does not separate the thoracic cavity from the abdominal cavity.
The sternum is a long flat bone located in the central part of the chest. Ribs are attached to the sternum. There are three parts of the sternum:
Manubrium (top)
Body (middle)
Xyphoid process (bottom)
Below is a diagram of the various body cavities. Note that the thoracic cavity and abdominal cavity are separated by the diaphragm.
 11ec0fda_9994_ddbc_a67f_351cf8b689f6_NR0004_00 Connexions / CC BY (https://creativecommons.org/licenses/by/3.0)

Which Structure Lies Between the Thoracic and Abdominal Cavities