Thoracic outlet

The thoracic outlet is the lower opening of the thoracic cavity whose edges are the lowest ribs. It is closed by the diaphragm, which separates the thoracic cavity from the abdominal cavity. The thoracic outlet or inferior thoracic aperture is much larger than the thoracic inlet (superior thoracic aperture).

The thoracic outlet is bounded by:

Structures passing through the thoracic outlet between the thorax and abdomen include the inferior vena cava and esophagus, both of which pass through the diaphragm, and the abdominal aorta and thoracic duct which pass through the diaphragm, through the aortic hiatus.