Anatomy, Thorax, Diaphragm

The diaphragm in the thorax is called the thoracic diaphragm and serves as an important anatomical landmark that separates the thorax, or chest, from the abdomen. It functions during breathing when it contracts to enlarge the thoracic cavity and reduce the intrathoracic pressure so that lungs may expand and fill their alveoli with air. It is a dome-shaped muscle and tendon that functions as the main muscle of respiration and is essential to the breathing process. It is a fibromuscular sheet that has a convex upper surface that forms the floor of the thoracic cavity and a concave under surface to form the roof of the abdominal cavity. The esophagus, phrenic, and vagus nerves, descending aorta, and inferior vena cava pass through the diaphragm between the thoracic and abdominal cavities. The diaphragm is asymmetric with the left side slightly more inferior than the right, chiefly because of the presence of the liver located on the right. The left side may also be partially inferiorly located because of the push by the heart.,