

MUSCLES OF THE FOREARM. 



UT 



The flexor longus pollicis (Fig. 228) arises, fleshy, be- 

 neath the flexor sublimis from the front part of the ra- 

 dius, below its tubercle, for about two-thirds of its extent, 

 and from the radial portion of the inter- FIG. 228. 

 osseous ligament. It also has a ten- 

 dinous origin from the inner condyle. 

 Its tendon passes beneath the annular 

 ligament, and between the two heads of 

 the short flexor and sesamoid bones, to be 

 inserted into the second phalanx of the 

 thumb. A bursa is seen in connection 

 with the tendon of this muscle. 



Function. To bend the last phalanx 

 of the thumb. 



The pronator quadratus (Fig. 228) 

 arises from the anterior front surface of 

 the lower extremity of the ulna, broad, 

 tendinous and fleshy, passes transversely, 

 and is inserted into the lower front sur- 

 face of the radius. It is a small, square 

 muscle, concealed by the flexor longus 

 pollicis and flexor profundus. 



Function. To pronate the hand by 

 rolling the radius inward. 



The muscles on the posterior part of 

 the forearm include the supinators and extensors, and com- 

 prise ten muscles, viz : the supinator radii longus, exten- 

 sor carpi radialis longior, extensor carpi radialis brevior, 

 extensor carpi ulnaris, extensor digitorum communis, supi- 

 nator radii brevis, extensor ossis metacarpi pollicis manus, 

 extensor minor pollicis, extensor major pollicis, indicator. 



Supinator radii longus. Dissection. Make an incision 

 along the middle of the back part of the arm and forearm. 

 Make a second incision transversely about the middle of 



FIG. 228 represents the deep muscles on the front of the Forearm, a Internal 

 lateral ligament, b Capsular ligament, c Coronary ligament, d Flexor pro- 

 fundus perforans. t Flexor longus pollicis. /Pronator quadratus. g Adductor 

 pollicis manus. /i Lumbricales. i Interossei. 



