Thoracic diaphragm

The diaphragm is a dome-shaped muscle that is in between the thorax and the abdomen.

File:Diaphragm-thieme.png

Diaphragm

Openings in the diaphragm

It has three openings in it for structures that have to pass from the thorax to the abdomen.

Openings

There are a number of openings in the diaphragm through which structures pass between the thorax and abdomen. There are three large openings—the aortic, the esophageal, and the caval opening—plus a series of smaller ones.

Human diaphragm, frontal view from below, showing openings

The esophagus, phrenic nerve, and vagus nerves, descending aorta, and inferior vena cava pass through the diaphragm between the thoracic and abdominal cavities.

Symmetry

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.

Crura and central tendon

The left and right crura are tendons that blend with the anterior longitudinal ligament of the vertebral column.

Central tendon

The central tendon of the diaphragm is a thin but strong aponeurosis near the center of the vault formed by the muscle, closer to the front than to the back of the thorax, so that the posterior muscular fibers are the longer.