405 



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 cms, 

 larger and longer than the left, arises from the anterior surfaces of the bodies and 

 intervertebral fibrocartilages of the upper three lumbar vertebrae, while the left 

 eras arises from the corresponding parts of the upper two only. The medial ten- 

 dinous 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. 



Xiphoid process 



Last Rib 

 Opening for Lesser Splanchnic Nerve 



FIG. 391. The diaphragm. Under surface. 



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 laterahvard to the central tendon. The medial fibers of the right crus ascend 

 on the left side of the esophageat 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 ). 



1 Journal of Anatomy and Physiology, vol. xlii. 



