DIAPHKAGMATIC KEGIOX. 



209 



down the central line of the tendinous portion, and gradually 

 blend with its fibres. Near the centre of the diaphragm, and a 

 little to the right, is a large opening, the foramen dextrum, 

 through which passes the posterior vena cava. Between the 

 pillars superiorly is a second opening, the hiatus aorticus, through 

 which pass the posterior aorta, vena azygos, and thoracic duct. 

 Below this, the right crus forms towards the left a third opening, 

 the foramen sini strum, for the passage of the oesophagus and 

 pneumogastric nerves, accompanied by the j^leural artery. There 



Fig. 77. 



The diaphragm, and superficial muscles of the internal femoral region— viewed from below. 

 A, The diaphragm; a a. The tendinous centre; a' a', The fleshy periphery; a" a". The crura: 

 a'". The hiatus aorticus; a"", The foramen sinistrum ; a'"", The foramen dextrum; b. The sar- 

 torius ; c, The giacilis. 



are thus three openings — the hiatus aorticus above, the foramen 

 sinistrum in the middle, and the foramen dextrum below. 

 Certain of the sublumbar muscles originate partly in the thorax, 

 and the diaphragm forms arches which allow their passage, and 

 that of the sympathetic and splanchnic nerves ; these arches are 

 bounded by ligaments, the ligamenta arcuata ; outside the arches 

 the diaphragm is attached to the last rib by a broad fold of 

 elastic tissue. 



Helation. — Anteriorly with the pleura, which covers both it 



