POSTERIOR HUMERAL REGION. 



235 



Posterior Humeral Region. 

 Triceps extensor cubiti. 



Dissection. Remove the integument and fascia from the posterior 

 aspect of the upper arm. 



The TRICEPS (<rp7s xt$a*.a.}, three heads,) arises by three heads. 

 Considered in relation to their length, these heads have been named 

 long, short, and middle ; and in re- 

 ference to their position, internal, Fig. 97.* 

 external, and middle ; the term 

 middle, in the former case, referring 

 to the external head, and in the 

 latter case to the long head. This 

 has given rise to much confusion 

 and misunderstanding. I shall, 

 therefore, confine myself to the de- 

 signations derived from their rela- 

 tions. The external head arises 

 from the humerus, commencing im- 

 mediately below the insertion of the 

 teres minor, and from the intermus- 

 cular septum attached to the exter- 

 nal condyloid ridge. The internal 

 head (short ) arises from the hume- 

 rus, commencing immediately below 

 the insertion of the teres major, 

 and from the intermuscular septum 

 attached to the internal condyloid 

 ridge. The scapular head (long) 

 lies between the two others, and 

 arises from the upper third of the 

 inferior border of the scapula. The 

 three heads unite to form a broad 

 muscle, which is inserted by an apo- 

 neurotic tendon into the olecranon 

 process of the ulna ; a small bursa 

 is situated between its tendon and 

 the upper part of the olecranon. 



The scapular head of the triceps 

 passes between the teres minor and 

 major, and divides the triangular 



space between those two muscles into two smaller spaces, one of which 

 is triangular, the other quadrangular. The triangular space is bounded 

 by the teres minor, teres major, and scapular head of the triceps ; it 



* A posterior view of the upper arm, shewing the triceps muscle. 1. Its 

 external head. 2. Its long, or scapular head. 3. Its internal, or short head. 

 4. The olecranon process of the ulna. 5. The radius. 6. The capsular liga- 

 ment of the shoulder-joint. 



