MUSCLES OF THE PARIETES OF THE ABDOMEN. 395 



tvveen the spine and the notch of the cordiform tendon, a little 

 to the left of the middle line. It gives passage to the oesophagus 

 and the par vagum nerves along with it, and is rather a fissure 

 or a long elliptical foramen made by the separation and reunion 

 of the muscular fibres; for, above and below, at each end of the 

 ellipsis, these fibres decussate- one another in columns. To the 

 right of this foramen, and a little above its horizontal level, in 

 the back part of the cordiform tendon, is a very large and pa- 

 tulous foramen for the ascending vena cava, (Foramen Quad- 

 ratum.) Its form is between an irregular quadrilateral figure 

 and a circle ; its edges are composed of fasciculi of tendon 

 rounded off, and are not susceptible of displacement, or of al- 

 teration in their relative position to each other; by which means 

 is obviated any impediment which might arise from a different 

 arrangement, to the course of the blood in the ascending cava. 

 Almost in a vertical line below, and about three inches from 

 the foramen for the oesophagus, is the third hole, in the dia- 

 phragm, which affords passage to the aorta, (Hiatus Aorticus.) 

 It is just in front of the bodies of the three upper lumbar verte- 

 brae, and is a much longer elliptical hole than the ossophageal; 

 its lowest extremity or pole is constituted by the tendinous 

 crura of the diaphragm, and its upper by a decussation of mus- 

 cular fasciculi arising from them. Through it,besides the aorta, 

 pass the Thoracic Duct, and the Great Splanchnic Nerve of 

 both sides. 



In the horizontal position of either the dead or the living 

 body, the right side of the diaphragm ascends higher in the 

 thorax than the left ; but the weight of the liver makes it, in 

 the vertical posture, descend lower than the other. 



Thus circumstanced, the detailed origin of the Diaphragm is 

 as follows : It arises fleshy from the internal face of the upper 

 edge of the Xiphoid Cartilage, from the internal face of the car- 

 tilages of the seventh true, and of the succeeding false ribs, 

 on each side; that is, from the cartilages of the eighth and ninth, 

 from the osseous extremities of the tenth and eleventh, and from 

 both the osseous and cartilaginous termination of the twelfth 

 rib. As the line described includes almost the whole of a 

 circle, and the fibres all converge to the cordiform tendon, 

 they, of course, will pass in different radiated directions, and 

 be of different lengths, which it is unnecessary to specify. Be- 



