MYOLOGY 167 



the abductor of the arm ; it arises from the postero-superior 

 angle of the scapula (the inferior angle of the human 

 scapula), from which it passes to be inserted into the internal 

 surface of the humerus. 



It is covered by the latissimus dorsi and the posterior 

 muscular mass of the arm. 



In brief, for the better understanding of the relations of the 

 teres major and minor muscles in quadrupeds, we may fancy 

 the corresponding muscles in man modified in the following 

 manner : The infraspinatus, thicker, covering the teres minor ; 

 latissimus dorsi, more extended in its superior part, covering 

 a large proportion of the teres major. As to the relations 

 of the teres minor with the deltoid, they exist in man, 

 seeing, in this case, the same muscle is, in its external 

 portion, covered by this latter. With regard to the relations 

 of the teres major with the posterior muscular mass of the 

 arm, they also exist in man, since the external surface of 

 this muscle is covered by the triceps. 



These modifications are sufficient to render the small and 

 large teres muscles completely invisible in the superficial 

 layer. 



The muscles of the shoulder which we have just been 

 studying fulfil, with regard to the articulation which they 

 surround, the function of active ligaments. This role 

 is made necessary by the laxity of the scapulo-humeral 

 capsule — a laxity which renders it incapable by itself of 

 maintaining the bones in contact at this joint. 



The same condition exists in man. 



Panniculus Muscle of the Shoulder. — This thin muscle 

 covers, as its name implies, the region of the shoulder, and 

 is the continuation forward of the panniculus muscle of the 

 trunk. 



It arises, by its superior part, from the region of the 

 withers and from the superior cervical ligament ; thence its 

 fibres descend directly towards the elbow, to terminate at 

 the level of the region of the forearm. 



The muscle is not found in the pig or in the carnivora. 



