Final answer:
The space in the thoracic cavity behind the sternum and between the two pleural sacs is called the mediastinum (option b). It contains the heart within the pericardial cavity and is flanked by the lungs within the pleural cavities.
Step-by-step explanation:
The space in the thoracic cavity that lies behind the sternum and between the two pleural sacs is called the mediastinum. The thoracic cavity is subdivided into the pleural cavities, which hold the lungs, and the mediastinum, which contains the heart within the pericardial cavity.
The diaphragm forms the floor of the thoracic cavity, separating it from the abdominopelvic cavity.
The heart, located in the mediastinum and encased in the pericardial cavity, is flanked by the lungs, which are surrounded by the pleural cavity.
Answer choices:
- Pericardial Cavity
- Mediastinum
- Pleural Cavity
- Thoracic Inlet