OSTEOLOGY AND ARTHROLOGY 



21 



The Scapula or Omoplate. — The scapula is situated 

 on the lateral surface of the thorax, and is directed obliquely, 

 from above downwards and from behind forwards. 



We must first recall, so as to be able to make a comparison, 

 that in man this bone is placed at the posterior surface of the 

 thoracic cage ; so that if we look at the human thorax 

 on one of its lateral aspects we see chiefly the external 

 border of the scapula ; it is the external surface (homo- 

 logous to the posterior surface of the human scapula) which 

 we see in its full extent when we look on the same surface 

 of the thorax in quadrupeds. 



Fig. 9. — Anterior Limb of the Seal : Left Side, External Surface. 



I, Scapula ; 2, humerus ; 3, radius ; 4, ulna ; 5, carpus ; 

 6, metacarpus ; 7, phalanges of the fingers. 



To sum Up, if we fancy the human being in the position 

 of the quadruped, the scapula will have its surfaces almost 

 parallel to the ground (Fig. 10) ; while in quadrupeds, the 

 surfaces are situated in a plane which is almost perpendicular 

 to the ground (Fig. 11). This position of the scapula in an 

 almost vertical plane is designed to give the necessary point 

 of support to the osseous columns that form the skeleton 

 of the other portions of the anterior limbs. 



Because of this position of the scapula (Figs. 12 and 13), 

 the spinal border is superior, the cervical, anterior, and the 

 axillary, posterior. In direct contrast to what obtains in the 

 human scapula, the spinal border is the shortest of the 



