194 



ANATOMY OF THE ABDOMEN, ETC 



indigitate with the transversalis muscle of the abdomei 

 (p. 166); also from a fibrous arch called the ligamentw 

 arcuatum externum, extending from the tip of the last rib 

 to the transverse process of the first lumbar vertebra, and 

 curving over the quadratus lumborum muscle ; it further 

 arises from a smaller fibrous arch called the ligamentum 

 arcuatum internum, which stretches from the termination 

 of the preceding to the body of the second lumbar vertebra, 

 curving over the psoas magnus muscle; and also from the 

 bodies of the second and third lumbar vertebrae by tendin- 

 ous fibres which are common to it and the anterior common 

 ligament of the vertebrae. From this circumference the 

 fibres converge to be inserted into the central tendon, a 

 glistening expansion in the centre of the muscle, the 

 metallic brilliancy of which has given it the name of 

 speculum of Van Helmont. The above description is of 

 what is called the larger muscle of the diaphragm. The 

 lesser muscle consists of two fleshy bundles arising by 

 separate tendons from the lumbar vertebrae j the right is 

 the larger and the longer ; it is connected with the bodies 

 and intervertebral cartilages of the upper four lumbar 

 vertebras ; the left bundle takes its origin from only the 

 upper three ; both are inserted into the central tendon. 

 These tendons are also called the pillars or crara of the 

 diaphragm, and the left one is sometimes wanting. The 

 right pillar crosses the left pillar in such a way as to divide 

 the interval between them into two separate parts ; the 

 lower, parabolic in shape, gives passage to the aorta, vena 

 azygos, and thoracic duct ; the upper, elliptical in shape, 

 transmits the oesophagus and the pneumogastric nerves. 

 In the central tendon is a third opening, the largest of all, 

 which transmits the vena cava inferior. 



The diaphragm, on the thoracic side, is covered by the 

 pleura and the pericardium, the fibrous layer of which 

 blends with the central tendon. 



The diaphragm is supplied by the phrenic nerves, and is 

 nourished by the phrenic arteries and by the musculo- 

 phrenic branch of the internal mammary artery. 



The RECEPTACULUM CHYLI, ordinarily the commencement 

 of the thoracic duct (p. 123), lies close beside the right 

 pillar of the diaphragm, and between the aorta and vena 

 cava ; it usually rests upon the second lumbar vertebra, 

 and consists of a thin, semi-transparent, membranous sac, 



