THE TRICEPS. 



Dissection (fig. 22). On the back of the arm there is one muscle, Lay bare the 

 the triceps, beneath which are placed the musculo-spiral nerve and tnce P s 

 superior profimda vessels. The skin having been reflected and 

 the bursa over the olecranon process having been looked for, the 

 muscle will be laid bare readily, for it is covered only by fascia. 

 To take away the fascia, carry an incision along the middle of the 

 limb to the point of the elbow ; and in reflecting it the loose 

 subaponeurotic tissue should be removed at the same time. 



Supraspinatus. 



Infraspinatus. 

 Teres minor. 



Outer head of triceps. 



Brachialis anticus. 



Supinator longus. 



^ External condyle. 



Internal condyle. "' 



Trochlea. 

 FIG. 21. THE HUMERUS FROM BEHIND. 



Separate the middle from the inner and outer heads of the and separate 

 muscle, and clear the interval between them, tracing the musculo- pl 

 spiral nerve and vessels beneath the muscle. Define the outer 

 head, which reaches down to the spot at which the musculo-spiral 

 nerve appears on the outer side. 



The TRICEPS MUSCLE (fig. 22) is divided superiorly into three Triceps^ 

 heads of origin, inner, outer, and middle. Two of these are attached 

 to the humerus, and one to the scapula. 



The middle or long head (A) has a tendinous origin, about an inch or }g of 

 wide, from a rough mark on the axillary margin of the scapula head, 

 close to the glenoid cavity, where it is united with the capsule of 

 the shoulder-joint. The outer head (B) arises from the back of the of outer 



head. 

 E 2 



