542 



MAMMALIAN ANATOMY 



The coracoid process is relatively longer and projects beyond the 

 head. The outline of the glenoid cavity is similar, but normally the 

 supraglenoid tubercle is smaller. 



THE HUMERUS. 



FIG. 426. 



Vertebral Column. 



Hyoid. 



Clavicle. 

 Sternum,. 



Metacarpus. 



Metatarsus. 

 Phalanges. 



THE SKELETON OF THE CAT. (LEFT SIDE ONLY.) 



General Description. The Huraerus is the single, long cylin- 

 drical bone of the arm. Its articulation above with the shoulder 

 girdle at the glenoid cavity of the scapula forms the shoulder-joint, 

 and its articulation below with the upper ends of the radius and 

 the ulna forms the elbow-joint. It is covered with muscles, through 

 which its size and form can be easily distinguished. The upper end 

 constitutes the prominence of the shoulder, and the lower end the 

 point of the elbow. The humerus has a considerable range of motion 

 at the shoulder-joint, and at rest usually it occupies a more or less 

 oblique position, with the upper end directed forward and the lower 

 end directed backward. As this position is not constant, for con- 

 venience of description the bone may be held vertically, with the 

 upper and larger end above, and the anterior surface, which is convex 

 from above downward, in front. The length of the humerus is from 

 twelve to fourteen times greater than the width at the middle part of 

 the shaft. It is in the main straight, except where bent backward at 

 the upper end. The greatest diameter of the upper part, which is the 

 antero-posterior diameter, is contained about four and a half times in 

 the greatest length of the bone, and the greatest diameter of the lower 

 end, which is the transverse, is contained about five times in the length. 



