DISSECTION OF THE ANTERIOR LIMB. 17 



which are distributed to these muscles and the supraspinatus (Plate 7). 

 It is accompanied by the circumflex nerve. 



3. Other branches of the subscapular are as follows : — A few inches 

 above the origin of the posterior circumflex, a vessel is detached which 

 passes backwards, and divides to supply the caput magnum. A number 

 of smaller branches come off" from the anterior aspect of the vessel, and 

 are distributed on both surfaces of the scapula. One of these supplies 

 the nutrient artery of the scapula. 



The ScAPULO-HUMERALis GRACILIS is a very slender muscle. It arises 

 from the scapula above the rim of its glenoid cavity ; and passing over 

 the capsular ligament of the shoulder, on which some of its fibres seem 

 to terminate, it insinuates itself between the fibres of the brachialis 

 anticus (humeralis externus), and is inserted into the posterior surface of 

 the shaft of the humerus. It is supplied by a small nerve from the 

 circumflex. 



Action. — The muscle is too inconsiderable in size to exercise any 

 appreciable action on the joint over which it passes, and, probably, its 

 function is to raise the capsular ligament and prevent its injury during 

 flexion of the joint. 



OUTER ASPECT OF THE SHOULDER AND ARM. 



Directions. — The limb is now to be turned over, and the muscles and 

 other structures on the outer side of the scapula and humerus are 

 to be dissected. 



Scapular Fascia. — This is a strong, glistening, fibrous covering which 

 is spread over the muscles on the dorsum of the scapula, aftbrding by 

 its inner surface an origin to many of their fibres. When traced 

 upwards, it is seen to be inserted into the scapula or its cartilage of pro- 

 longation; while before, behind, and inferiorly, it becomes less fibrous, 

 and is continuous with the fascia covering the muscles on the inner 

 surface of the scapula and the outer aspect of the arm. It furnishes 

 septa to pass between the subjacent muscles, and it is adherent to the 

 tubercle on the scapular spine. If an attempt be made to dissect 

 it off" these mtiscles, they will be exposed with a rough surface, 

 showing that they there take origin from the inner aspect of the 

 fascia. 



The Deltoid Muscle (scapular portion) (Plates 4 and 7). This muscle 

 Avas by Percivall en-oneously termed the teres minor. It is not the 

 homologue of either of the teres muscles of human anatomy, but is, most 

 clearly, the representative of that part of the deltoid muscle which in 

 man takes origin from the scapula. A linear depression Avhich traverses 

 the muscle corresponds to an imperfect division of it into an anterior 

 and a posterior portion. It arises by its anterior poi-tion from the 



c 



