The three main compartments of the thoracic cavity are:
Right pleural cavity: Located in the right side of the chest
Left pleural cavity: Located in the left side of the chest
Mediastinum: Located in the middle of the chest, between the two pleural cavities
The mediastinum contains the heart and other structures. The left pleural cavity contains the left lung, and the right pleural cavity contains the right lung.
The thoracic cavity is bounded by the ribs, sternum, vertebral column, and diaphragm. The diaphragm separates the thoracic cavity from the abdominal cavity.
The pleural cavity contains a small amount of serous fluid and is usually not visible. It's lined by a serous membrane called pleura.
The visceral pleura is the serous membrane that covers the lung's surface. The parietal pleura lines the thoracic wall and forms the mediastinum.
The visceral pleura is separated from the parietal pleura by a film of pleural fluid. The right and left pleural cavities communicate through a mediastinal tunnel.
The left pleural cavity is smaller than the right one. This is because the heart in the mediastinum projects to the left hand side of the thoracic cavity, limiting the space available for the left lung and its corresponding pleural cavity.
The mediastinum is divided into the superior and inferior mediastinum, with the inferior being larger. The inferior mediastinum is further divided into the anterior, middle, and posterior mediastinum.
The mediastinum contains the heart, thymus gland, parts of the esophagus and trachea, and other structures. It also contains the arch of the aorta and its three main branches: the brachiocephalic trunk, the left common carotid, and the left subclavian arteries.
Many conditions can affect the organs and tissues in the mediastinum, including tumors and infections. The most common posterior mediastinal tumors are neurogenic tumors, which form in nerve tissue. Most neurogenic tumors are benign.