The thoracic cavity is the chamber of the human body (and other animal bodies) that is enclosed by the ribcage and the diaphragm. It houses

• the lungs,
• the heart,
• the thoracic aorta,
• the main pulmonary artery and its branches,
• the thymus gland,
• the trachea and bronchi and
• the esophagus.

It contains the potential space called the pleural cavity and the mediastinum.

If the thoracic cavity is breached from the outside, as by a bullet wound or knife wound, a pneumothorax, or air in the cavity, usually results, often leading to one or both lungs collapsing and requiring immediate medical attention.