THE MUSCLES . 95 



(27) Biceps brachii (Fig. 57); bicipital tubercle of scapula to 

 proximal end of radius; flexor of arm and supinator of hand. 



(28) Brachialis (Fig. 55); lateral surface of humerus to 

 proximal end of ulna; flexor of forearm. 



(29) Triceps brachii (Figs. 54, 55); divisible into three 

 main portions: 



(a) Caput later ale (Fig. 54) (Anconeus lateralis or ectotriceps) ; 

 proximal end of humerus to olecranon process of ulna. 



{h) Caput longum (Fig. 54) (Anconeus longus or mediatri- 

 ceps); glenoid border of scapula to olecranon process of ulna. 



{c) Caput mediale (Fig. 55) (en to triceps) ; consists of three 

 parts: 



(x) Long portion (Anconeus posterior) ; shaft of humerus to 

 ulna. 



(}') Intermediate portion (Anconeus internus); humerus to 

 olecranon. 



(z) Short portion; supracondyloid bar to olecranon. 

 Triceps forms strong extensor of forearm; short portion alone 

 acts as supinator of hand. 



(30) Anconeus ; distal portion of humerus to proximal end of 

 ulna; tensor of capsule of joint. 



MUSCLES OF THE FOREARM (ANTIBRACHIUM) 

 SUPINATORS AND EXTENSORS 



Note that the muscles of the forearm are covered by a tough 

 antrbrachial fascia which is made up of a superficial and a deep 

 layer. At the wrist the fascia becomes thickened to form, on 

 the ventral side, the transverse ligament, holding the flexor 

 tendons in place. On the fingers it forms tendinous sheaths 

 (vaginal ligaments) for the flexor muscles and ring-like annular 

 ligaments for the flexor tendons. 



(31) Brachioradialis (Fig. 56) (supinator longus); from the 

 middle fifth of the humerus to the styloid process of the radius; 

 supinator of hand. 



