Crus of diaphragm
Encyclopedia
The crura of the diaphragm (singular: crus) are tendinous
structures that extend inferiorly from the diaphragm to attach to the vertebral column
. Forming a tether for muscular contraction, they take their name from their leg-shaped appearance (crus is Latin for leg).
of the vertebral column
.
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.
Tendon
A tendon is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments and fasciae as they are all made of collagen except that ligaments join one bone to another bone, and fasciae connect muscles to other...
structures that extend inferiorly from the diaphragm to attach to the vertebral column
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
. Forming a tether for muscular contraction, they take their name from their leg-shaped appearance (crus is Latin for leg).
Structure
At their origins the crura are tendinous in structure, and blend with the anterior longitudinal ligamentAnterior longitudinal ligament
The anterior longitudinal ligament is a ligament that runs down the anterior surface of the spine. It traverses all of the vertebral bodies and intervertebral discs....
of the vertebral column
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
.
- 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 vertebraeLumbar vertebraeThe lumbar vertebrae are the largest segments of the movable part of the vertebral column, and are characterized by the absence of the foramen transversarium within the transverse process, and by the absence of facets on the sides of the body...
. - 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
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
known as the median arcuate ligament
Median arcuate ligament
The median arcuate ligament is a ligament under the diaphragm that connects the right and left crura of diaphragm.-Structure:The median arcuate ligament is formed by the right and left crura of the diaphragm...
; this arch is often poorly defined. The area behind this arch is known as the aortic hiatus
Aortic hiatus
The aortic hiatus is a hole in the human diaphragm. It is the lowest and most posterior of the large apertures.It is located approximately at the level of the twelfth thoracic vertebra .-Structure:...
.
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
Xiphoid process
The xiphoid process, or xiphisternum or metasternum, is a small cartilaginous process of the lower part of the sternum which is usually ossified in the adult human. By age 15 to 29, the xiphoid usually fuses to the body of the sternum with a fibrous joint. Unlike the synovial articulation of major...
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
Esophageal hiatus
In human anatomy, the esophageal hiatus is a hole in the diaphragm through which the esophagus passes. It is located in the right crus of the diaphragm.It is located approximately at level of the tenth thoracic vertebra ....
, 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.