32 



DISSECTION OF THE UPPER LIMB, 



and inser- 

 tion ; 



adjacent 

 parts. 



It consists 

 of three 

 parts, 



and from the outer half or third of the front of the clavicle (fig. 5). 

 Its fibres converge to a tendon which is inserted into the rough 

 triangular impression on the outer surface of the humerus, above 

 the middle (fig. 1 7, p. 44). 



The anterior border is contiguous to the pectoralis major muscle ; 

 and the posterior rests on the infraspinatus, teres, and triceps 

 muscles. The origin of the muscle from the bones of the shoulder 

 corresponds with the insertion of the trapezius. At its insertion 

 the tendon of the deltoid is united with that of the pectoralis 

 major ; and a fasciculus of the brachialis anticus is attached to the 

 humerus on each side of it. 



The middle or acromial portion of the deltoid is thicker than 

 the rest, and its fibres form large bundles which run obliquely 



Short head of biceps and coraco-brachialis. 



Trapezius. 



Glenoid ligament. 



Triceps (long head). 



Rhomboideus 

 miner. 



Latissimus dorsi. 



FIG. 12. THE SCAPULA FROM BEHIND. 



between tendinous septa prolonged from the origin and insertion of 

 the muscle. The anterior or clavicular and posterior or spinous 

 portions are somewhat separate from the foregoing, and their fibres 

 converge to the anterior and posterior edges respectively of the 

 lower tendon. 



Action. The acromial portion of the muscle raises the arm, 

 abducting it from the body ; the clavicular part flexes the 

 shoulder-joint, moving the arm forwards and inwards; and the 

 spinous part draws the arm backwards, or extends the shoulder- 

 joint. 



Dissection (fig. 13). The deltoid is to be divided near its origin, 

 an d is to be thrown down as far as the circumflex vessels and nerve 

 Subacromial beneath will permit. As the muscle is raised a large thick bursa 

 between it and the upper end of the humerus comes into sight, 



which have 



different 



uses. 



Dissection 





