84 



PHYSIOLOGY. 



which as life advances, are reduced to three ; and, in old 

 age, are united into one. It terminates below in a sharp- 

 pointed cartilage, which lies over the stomach, and may be 

 felt externally. It is somewhat hollowed beneath at its 

 upper end for the passage of the treachea or wind-pipe, 

 which lies directly under it ; and on each side there are 

 seven oval depressions for admitting the cartilaginous ex- 

 tremities of the first seven ribs. 



40. The sternum in this cut consists of two bones. The 

 first is broad and thick above, and contracts as it descends. 

 It is convex before and concave behind. At the upper angle 

 a, the collar-bone is articulated ; b, the articular surface for 

 the cartilage of the first rib ; 6, for second rib ; e, d, e, f, g, 

 mark the articular surfaces of the 3d, 4th, 5th, 6th, and 7th 

 ribs ; h, the ensiform cartilage, terminates the lower extrem- 



