|Henry Gray (18251861). Anatomy of the Human Body. 1918.|
|lumbar vertebra; laterally, it is fixed to the front of the transverse process of the first and, sometimes also, to that of the second lumbar vertebra.|
| The Lateral Lumbocostal Arch (arcus lumbocostalis lateralis [Halleri]; external arcuate ligament) arches across the upper part of the Quadratus lumborum, and is attached, medially, to the front of the transverse process of the first lumbar vertebra, and, laterally, to the tip and lower margin of the twelfth rib.|
The Crura.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 vertebræ, while the left crus arises from the corresponding parts of the upper two only. The medial tendinous margins of the crura pass forward and medialward, and meet in the middle line to form an arch across the front of the aorta; this arch is often poorly defined.
FIG. 391 The diaphragm. Under surface. (See enlarged image)
| 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 (Low 1).|
|Note 1. Journal of Anatomy and Physiology, vol. xlii. [back]|