ANATOMY. 



phalanges by 4 tendons which are split for the passage 

 of the deep flexor tendons. Action, to flex the second 

 phalanges. Nerve, median. 



Flexor Profundus Digitorum (Perforans), from the 

 upper two-thirds of the shaft of the ulna, a de- 

 pression on the inner side of the coronoid process, 

 and the interosseous membrane, into the bases of 

 the last phalanges, by 4 tendons which perforate 

 the tendons of the superficial flexor. Action, to 

 flex the phalanges. Nerves, ulnar, and anterior 

 interosseous. 



Flexor Longus Pollicis, from the upper two-thirds 

 of the shaft of the radius, and the interosseous 

 membrane, into the base of the last phalanx of 

 the thumb, which it flexes. Nerve, anterior inter- 

 osseous. 



Pronator Quadratus, from the oblique line on the 

 lower one-fourth of the ulna, and the internal body 

 of the ulna, into the lower one-fourth of the ex- 

 ternal border of the shaft of the radius. Action, to 

 pronate the hand. Nerve, anterior interosseous. 



Supinator Longus, 13 from the upper two-thirds of the 

 external condyloid ridge on the humerus, and the 

 intermuscular septum, into the base of the styloid 

 process of the radius. Action, to supinate the hand. 

 Nerve, musculo-spiral. 



Extensor Carpi Radialis Longior/ from the lower one-third of the external 

 condyloid ridge on the humerus, and the intermuscular septum, into the 

 base of the metacarpal bone of the index finger,^ on its radial side. Action, 

 to extend the wrist. Nerve, musculo-spiral. 



Extensor Carpi Radialis Brevior,/ /n?;?z the external condyle by the common 

 tendon, the external lateral ligament, and the intermuscular septa, into the 

 radial side of the base of the 3d metacarpal bone.^ Action, to extend the 

 wrist. Nerve, posterior interosseous. 



Extensor Communis Digitorum/* from the external condyle by the common 

 tendon, the deep fascia, and the intermuscular septa, into the 2d and 3d 

 phalanges of all the fingers, by 3 tendons, one of which divides into two, 

 Action, to extend the fingers. Nerve, posterior interosseous. 



