i8 THE ARTISTIC ANATOMY OF ANIMALS 



are called false, or asternal. The longer ribs are those 

 situated in the middle region of the thorax. 



The ribs are directed obliquely downwards and backwards, 

 and this obliquity is more marked in the posterior ones than 

 in the anterior. They are, however, less oblique than in 

 the human being ; what proves this is that the first rib in man 

 is oblique, while in quadrupeds it is vertical. 



The curvature of the ribs is less pronounced in quadrupeds 

 than in the human being, but this is not equal in all animals. 

 The ribs of the bear are more curved than those of the dog ; 

 the latter has ribs more curved than those of the horse. 



Each rib, at its vertebral extremity, presents, from within 

 outwards, a wedge-shaped head for articulation with two 

 dorsal vertebrae, a neck, and a tuberosity. External to the 

 tubercle are found some rough impressions, for muscular 

 attachments, which correspond to the angle of the human 

 rib. 



In the following table, we give the number and classifica- 

 tion of the ribs of some animals : 



Number of the Ribs on Each Side of the Thorax. 



The costal cartilages, by which the first ribs are united to 

 the sternum (sternal ribs), whilst the latter are united one 

 to the other without being directly connected with the 

 sternum (asternal ribs), are, as a rule, in quadrupeds, directed 

 obliquely downwards, forwards, and inwards ; each forms, 

 with the rib to which it belongs, an obtuse angle more or less 

 open anteriorly. Their length is proportionate to that of 

 the ribs. The cartilages, which are continued from the 

 asternal ribs, unite and form the borders, directed obliquely 

 downwards and forwards, of the fossa which is found at the 



