The thoracic cavity is a major body compartment within the ventral body cavity, specifically located between the neck and the diaphragm. It serves as a protective and functional space for several critical organs primarily involved in respiration and circulation.

Anatomically, the thoracic cavity is enclosed by the thoracic cage (ribs, sternum, and thoracic vertebrae) and the diaphragm, a dome-shaped muscle that separates it from the abdominal cavity and plays a key role in breathing. The cavity is subdivided into three smaller compartments:

Two pleural cavities – each surrounding a lung and lined with a double-layered membrane called the pleura. The pleural fluid between these layers reduces friction during breathing.

The mediastinum – the central compartment that contains the heart (within the pericardial cavity), thymus, trachea, esophagus, and major blood vessels like the aorta, pulmonary arteries and veins, and superior and inferior vena cavae.

Functionally, the thoracic cavity protects these organs from mechanical injury and supports their physiological roles. For example:

The lungs perform gas exchange, allowing oxygen to enter the blood and carbon dioxide to exit.

The heart circulates blood throughout the body, supplying tissues with oxygen and nutrients.

The diaphragm, by changing the pressure inside the cavity, enables inhalation and exhalation.

Additionally, the thoracic cavity maintains pressure differentials essential for respiration, and its structure is adapted to expand and contract rhythmically to accommodate the breathing cycle