THE DIAPHRAGM. 193 



tween the thoracic and abdominal cavities. It arises 

 posteriorly by two crura, which are flat, ligamentous 

 bands attached to the anterior surface of the bodies of 

 the lower four lumbar vertebrae ; also, it arises from the 

 ligamenta arcuata interna and externa, which are fibrous 

 arches thrown over the psoas magnus and quadratus lum- 

 borum muscles, the ligamentum arcuatum internum 

 being attached to the side of the body of the first lumbar 

 vertebra and attached to the base of the transverse process 



FIG. 87. THE DIAPHRAGM. 



1, 2, 3, central cordiform tendon ; 4, middle leaflet ; 5, ligamentum arcuatum exter- 

 num ; 6. ligamentum arcuatum internum ; 8, right cms ; 10, left cms ; 11, aortic opening; 

 12, cesophageal opening ; 13, opening for vena cava ; 14, psoas magnus ; 15, qnadratus lum- 

 borum. 



of the second lumbar vertebra ; it is continuous with the 

 cms. The ligamentum arcuatum externum extends from 

 the base of transverse process of second lumbar vertebra 

 to the apex of the last rib. The diaphragm also arises 

 by a number of digitations from the inferior circumfer- 

 ence of the chest ; therefore, from the tip of the eleventh 

 rib, the costal cartilages of the false ribs, and the tip 

 of the ensiform cartilage. From these points of origin 

 the fibres pass inward to the central tendon, which con- 

 sists of a trefoil aponeurosis of white, fibrous tissue. 



13 



