106 



ANATOMY FOR NURSES 



[Chap. VII 



oesophagus, or gullet ; it has also some smaller openings for the 

 passage of blood-vessels, nerves, etc. The upper or thoracic sur- 

 face of the diaphragm is highly arched ; the heart is supported by 

 the central tendinous portion of the arch, the right and left lungs 

 by the lateral portions, the right portion of the arch being slightly 

 higher than the left. The lower or under surface of the diaphragm 



t||^\\ >^\' 



'^fK 



\ a! 



\ y 



Fig. 77. — Di.\phrag.m. Viewed from in front. (Gerrish.) 



is deeply concave, and covers the liver, stomach, pancreas, spleen, 

 and kidneys. 



Action. — The diaphragm is probably the most important 

 voluntary muscle in the body, as well as the chief respiratory 

 and expulsive muscle. In the act of inspiration the diaphragm 

 contracts, and in contracting flattens out and descends, the ab- 

 dominal viscera are pressed downwards, and the thorax is ex- 

 panded vertically. In forcible acts of expiration, and in efforts of 

 expulsion from the thoracic and abdominal cavities, the diaphragm 

 and all the other muscles which tend to depress the ribs, and those 

 which compress the abdominal cavity, concur in powerful action 

 to empty the lungs, to fix the trunk, and to expel the contents of 



