230 



POSTERIOR HUMERAL REGION. 



short head rests upon the subscapularis, from which it is separated by a 

 bursa. In the rest of its extent the muscle is in relation with the humerus, 

 the teres major, latissimus dorsi, and brachialis anticus ; from the latter it 

 is separated by the external cutaneous nerve. By its inner border with 

 the coraco-brachialis, brachial artery arid veins, and median nerve ; the 

 brachial vessels crossing its tendon at the bend of the elbow. By its 

 outer border with the deltoid and supinator longus. 



The BRACHIALIS ANTICUS is a broad muscle covering the whole of the 

 anterior surface of the lower part of the humerus ; it arises by two fleshy 

 serrations from the depressions on either side of the insertion of the del- 

 toid, from the anterior surface of the humerus, and from the intermuscular 

 septa attached to the condyloid ridges. Its fibres converge to be inserted 

 into the coronoid process of the ulna. 



Relations. By its anterior surface with the biceps, external cutaneous 

 nerve, brachial artery and veins, and median nerve. By its posterior sur- 

 face with the humerus, anterior ligament of the elbow joint, and inter- 

 muscular aponeurosis. The latter separates it from the triceps. By its 

 external border with the supinator longus, extensor carpi radialis longior, 

 musculo-spiral nerve, and recurrent radial artery. By its internal border 

 with the intermuscular aponeurosis, which separates it from the triceps 

 and ulnar nerve, and with the pronator radii teres. 



Actions. The coraco-brachialis draws the humerus inw r ards, and assists 

 in flexing it upon the scapula. The biceps and brachialis anticus are 

 flexors of the fore-arm, and the former a supinator. The brachialis anticus 

 is a powerful protection to the elbow joint. 



Fig. 121.* Posterior Humeral Region. 



Triceps extensor cubiti. 



Dissection. Remove the integument and fascia 

 from the posterior aspect of the upper arm. 



The TRICEPS (rpslg xstpaXaj, three heads) arises 

 by three heads. Considered in relation to their 

 length, these heads have been named long, short, 

 and middle; and in reference to their position, 

 internal, 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 misunderstand- 

 ing. I shall, therefore, confine myself to the de- 

 signations derived from their relations. The ex- 

 ternal head arises from the humerus, commencing 

 immediately below the insertion of the teres minor, 

 and from the intermuscular septum attached to the 

 external condyloid ridge. The internal head 

 (short) arises from the humerus, commencing im- 

 mediately below the insertion of the teres m:ijor, 

 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 



A posterior view of the upper arm, showing the triceps muscle. 1. Its external 

 hoad. 2. Its long, or scapular head. 3. Its internal, or short head. 4. The olecranou 

 process of the ulna. 5. Th rad>"3 6 The capsular ligament of the shoulder join:. 



