CHAPTER XVII. 

 THE DIAPHRAGM. 



OPENINGS OF LANDMARKS. 



RELATIONS. AFFECTIONS OF 

 ACTIONS. SUPHRENIC ABSCESS. 



The Diaphragm is a musculo-fibrous septum be- 

 tween the thoracic and the abdominal cavities and is com- 

 posed of a tendinous centre, trefoil, or, trilobed, in shape, 

 surrounded by muscular fibres. It presents an appear- 

 ance somewhat resembling the combined transversales 

 muscles of the abdomen, and arises, anteriorly, from the 

 ensiform cartilage, laterally, from the six lower ribs, and 

 posteriorly, from the sides of the vertebrae by two crura, 

 and from the thickened portions of the lumbar fascia, 

 termed the ligamentum arcuatum externum and internum. 



The poenings of the diaphragm are the 

 aortic, the cesophageal and the caval. The aortic 

 transmits the aorta, vena azygos major and the 

 thoracic duct, and is situated in front of the twelfth 

 dorsal vertebra, rather behind, than in the sub- 

 stance of the diaphragm. The oesophageal, trans- 

 mitting the oesophagus and the pneumogastric nerves, is in 

 front, and a little to the left of the aortic. This opening 

 is oval in shape, measuring half an inch by one inch, with 

 the long diameter forward and to the left, and is opposite 

 to the tenth dorsal vertebra. The caval transmits the in- 

 ferior vena cava and is quadrilateral in shape, situated in 

 front and to the right of the preceding, at the junction of 

 the right and middle leaflets of the central tendon, and is 

 opposite the disk between the eighth and ninth dorsal 

 vertebrae. The sympathetic and the greater and lesser 

 splanchnic nerves pass through the right cms, whereas, the 

 vena azygos minor and the two left spianchnics pass 

 through the left cms. 



