362 



MUSCLES SITUATED ON THE OS HUMERI. 



MiLscles situated on the Os Humeri. 

 These are called 



Muscles of the Cubit or Forearm. 



They consist of two before, and two behind. 

 Before are, 



Fig. 92.* 1. Biceps Flexor Cuhiti, 



Arises, by two heads. The first and 

 outermost called longus, begins tendinous 

 /\ from the upper edge of the glenoid cavity 

 ",' of the scapula, passes over the head of 

 : the OS humeri within the joint ; and, in 

 its descent without the joint, is enclosed in 

 a groove near the head of the os humeri, 

 by a membranous ligament that proceeds 

 from the capsular ligament and adjacent 

 tendons. The second or innermost head, 

 called brevis, arises tendinous and fleshy, 

 from the coracoid process of the scapula, 

 in common with the coraco-brachialis 

 muscle. A little below the middle of 

 the forepart of the os humeri, these heads 

 unite. 



Inserted, by a strong roundish tendon, 

 into the tubercle on the upper end of the 

 radius iiflernally.* 

 Use. To turn the hand supine, and to bend the forearm. 

 JV. B. At the bending of the elbow, where it begins to grow 

 tendinous, it sends off an aponeurosis which covers all the 

 muscles on the inside of the forearm, and joins with another 

 tendinous membrane, which is sent off from the triceps ex- 

 tensor cubiti, covers all the muscles on the outside of the 



* The muscles of the anterior aspect of the upper arm. 1. The coracoid 

 process of the scapula. 2. The coraco-clavicular ligament (trapezoid), passing 

 upwards to the scapular end of the clavicle. 3. The coraco-acromial ligament, 

 passing outwards to the acromion. 4. The subscapularis muscle. 5. The 

 teres major. 6. The coraco-brachialis. 7. The biceps. 8. The upper end of 

 the radius. 9. The brachialis anticus. 10. The internal head of the triceps. 



