MUSCLES OF THE PERINEUM. 



83 



FIG. 42. 



sternum, into the lower border and inner surfaces of the 2d, yl, 4th, and 

 5th costal cartilages. Action, to draw down the cartilages in expiration. 

 Nerves, intercostal. 



Levatores Costarum, 17 F 'g- 40 (12), ea.chfrvm the transverse process of a dorsal 

 vertebra, into the upper surface of the next rib below, near its angle. 

 Action, to raise the ribs. Nerves, intercostal. 



Diaphragm, from the ensiform cartilage,* inner surfaces of 6 or 7 lower ribs, 

 ligamenla arcuata, 5 and by its crura 8 10 from the bodies of the lumbar ver- 

 tebrae, from the 2d to 

 the 4th on the right 

 side, the 2d and 3d on 

 the left, into the cen- 

 tral or cordiform ten- 

 don. 2 3 Action, the 

 great muscle of respi- 

 ration and expulsion. 

 Nerve, the phrenic. 



Openings of the Dia- 

 phragm. The Aortic, 11 

 in the middle line pos- 

 teriorly, and behind 

 the diaphragm ; trans- 

 mits the aorta, vena 

 azygos major, and tho- 

 racic duct, occasionally 

 the left sympathetic 

 nerve. The CEsopha- 

 geal, 12 in the muscular structure, transmits the oesophagus and the pneumo- 

 gastric nerves. The Opening for the Vena Cava is the highest, and has 4 

 tendinous margins. The Right Crus 8 transmits the sympathetic and greater 

 and lesser splanchnic nerves of that side. The Left Crus, 10 the greater and 

 lesser splanchnic nerves of the left side and the vena azygos minor. 



Descent of the Diaphragm. Its central tendon does not descend during in- 

 spiration, being connected with the deep cervical fascia by the fibrous 

 pericardium. 



MUSCLES OF THE PERINEUM. 



Sphincter Ani, 4 from the tip of the coccyx and superficial fascia, into the 

 tendinous centre of the perineum. Action, to close the anus. Nerve, 

 hemorrhoidal branch of the pudic. 



