Crus of diaphragm

The crura of the diaphragm (singular=crus) are tendinous structures that extend downward from the diaphragm to attach to the vertebral column.

Structure
At their origins the crura are tendinous in structure, and blend with the anterior longitudinal ligament of the vertebral column.


 * The right crus, larger and longer than the left, arises from the anterior surfaces of the bodies and intervertebral fibrocartilages of the upper three lumbar vertebrae.
 * The left crus arises from the corresponding parts of the upper two lumbar vertebrae only.

The medial tendinous margins of the crura pass anteriorly and medialward, and meet in the middle line to form an arch across the front of the aorta known as the median arcuate ligament; this arch is often poorly defined. The area behind this arch is known as the aortic hiatus.

From this series of origins the fibers of the diaphragm converge to be inserted into the central tendon.

The fibers arising from the xiphoid process are very short, and occasionally aponeurotic; those from the medial and lateral lumbocostal arches, and more especially those from the ribs and their cartilages, are longer, and describe marked curves as they ascend and converge to their insertion. The fibers of the crura diverge as they ascend, the most lateral being directed upward and lateralward to the central tendon.

The medial fibers of the right crus ascend on the left side of the esophageal hiatus, and occasionally a fasciculus of the left crus crosses the aorta and runs obliquely through the fibers of the right crus toward the vena caval foramen.