28 THE THORAX. 



one vertebra ; and it may want the articular facet for the transverse process. The 

 twelfth rib varies in length from 8 inches to less than an inch ; complete suppression 

 is very rare. 



Fig. 23. TENTH, ELEVENTH, AND TWELFTH RIBS OF THE BIGHT SIDE, FROM BELOW. 

 (Drawn by D. Gunn. ) f 



The costal cartilages prolong the ribs towards the sternum. Their breadth 

 diminishes gradually from the first to the last, while their length increases as far as 

 the seventh, after which they become gradually shorter. Their line of direction 

 varies considerably. The first descends a little, the second is horizontal, and all the 

 rest, except the last two, ascend more and more from the rib towards the sternum as 

 they are situated lower down. The external or costal extremity, convex and uneven, 



