THE MUSCLES OF THE THOEAX. 



473 



quadratum) in the right lobe of the central tendon transmits the inferior vena 

 cava, and small branches of the right phrenic nerve. The hiatus cesophageus 

 (wsophageal opening} is in' the muscular substance of the diaphragm, posterior to 

 the central tendon, and is surrounded by a sphincter -like arrangement of the 

 crural fibres. Besides the oesophagus, this opening transmits the two vagi nerves. 



Middle arcuate ligament 



Vena caval 



opening 



(Esophageal opening in diaphragm 



i irior ramus 



rth lumbar 



nerve 



^ irior ramus 

 c fth lumbar 



( Medial and 



\ lateral lumbo : 



. I. costal arches 



Ant. ramus of twelfth 



thoracic nerve 



Quadratus 



lumborum 



Ilio-hypogastric 



nerve 



Ilio-inguinal nerve 



Psoas major 



Genito-femoral 

 nerve 



Lateral 



...cutaneous nerve 

 of thigh 



- Iliacus 



Lumbo-sacral 

 trunk 



Femoral nerve 



Obturator nerve 



FIQ. 420. THE DIAPHRAGM AND POSTERIOR ABDOMINAL WALL. 



The diaphragm is found as a complete septum between the thorax and abdomen only in 



amals. It is occasionally deficient in the human subject, producing hernia of the diaphragm, 



.nto the pericardial cavity through the central tendon, or into the pleural cavity through 



Lateral portions of the muscle. A rare condition is congenital deficiency of a part of the 



1 half of the muscle, generally placed posteriorly, and on the left side. This produces, by 



continuity of the pleural and peritoneal cavities behind the diaphragm, a congenital diaphragmatic 



