292 A MANUAL OF ANATOMY. 



Nerve Supply. Through the ulnar nerve by filaments 

 from the eighth cervical and first thoracic nerves. 



Action. It is a flexor and adductor of the wrist and a 

 weak flexor of the forearm. 



Supinator longus. (Brachioradialis^ Fig. 67. 



Be sure to carry the dissection of this muscle to its origin ; 

 save the nerves and arteries found. 



Origin. From the upper two-thirds of the external con- 

 dyloid ridge, from the external intermuscular septum of 

 the deep fascia of the arm. 



Insertion. Into the base of the styloid process of the 

 radius. 



Nerve Supply. The musculospiral from the sixth cer- 

 vical nerve. 



Action. Primarily it is a flexor of the forearm, second- 

 arily a pronator in complete supination of the forearm, 

 and has a slight action of supination only when the arm 

 is fully pronated. 



The Anterior Elbow Space. Fig. 66. 



The hollow in front of the elbow is bounded on the out- 

 side by the supinator longus, on the inside by the pronator 

 radii teres. Its floor is formed by the brachialis anticus. 



From without inward is found the musculospiral nerve 

 (dividing into its radial and posterior interosseous branches), 

 radial recurrent artery, musculocutaneous nerve (under 

 the outer margin of the biceps), the tendon of the biceps 

 muscle, the brachial artery and its terminal branches, the 

 ulnar and radial, and their accompanying veins, the median 

 nerve and its muscular branches, and the anastomosis 

 between the anterior branch of the anastomotica magna and 

 anterior ulnar recurrent. 



