CHAPTER YIIT. 



DIAPHRAGMATIC RKOION. 



Diaphragm.— Situated between the thoracic and ab- 

 dominal cavities, obliquely downwards and forwards. 

 In form it is flattened from forwards backwards, wider 

 above, convex on its anterior, aud concave on its pos- 

 terior faces. It is divided into a phrenic, central or 

 aponeurotic portion, and a peripheric or fleshy portion. 

 Attachments : By the tendons of its two fleshy pillars 

 on the bodies of all the lumbar vertebrse, by its fleshy 

 peripheral digitations on the superior face of the xyphoid 

 cartilage and the internal face of the last twelve ribs 

 near their inferior extremity. Structure : In the centre 

 of the phrenic portion is a foramen for the posterior 

 vena cava ; through the right pillar, one for the oeso- 

 phagus; between the two pillars another for the pos- 

 terior aorta and tlioracic duct. Action : Essentially 

 inspiratory. 



ArterieSt — Diaphragmatic: Two or three small 

 branches coming from the posterior aorta and ramify- 

 ing in the muscle. 



