Thoracic cavity

The thoracic cavity (or chest cavity) is the chamber of the human body (and other animal bodies) that is protected by the thoracic wall (thoracic cage and associated skin, muscle, and fascia). Structures within the thoracic cavity include:

• the heart,
• the great vessels, which include the thoracic aorta, the pulmonary artery and its branches, the superior and inferior vena cava, and the pulmonary veins
• other vascular structures such as the azygos vein,
• the trachea, bronchi and lungs
• the esophagus,
• the thymus gland,
• structures of the nervous system including the paired vagus nerves, and the paired sympathetic chains,
• structures of the lymphatic system, especially the thoracic duct.

It contains three potential spaces lined with mesothelium: the paired pleural cavities and the pericardial cavity. The mediastinum comprises those organs which lie in the centre of the chest between the lungs.

The thoracic cavity is separated from the abdominal cavity by the diaphragm. The thoracic inlet is the upper limit of the thoracic cavity, formed by the manubrium in front, the first ribs laterally and the spine posteriorly.

If the pleural cavity is breached from the outside, as by a bullet wound or knife wound, a pneumothorax, or air in the cavity, may result. If the volume of air is significant, one or both lungs may collapse, which requires immediate medical attention.