410 SPECIAL ANATOMY. 



the forearm between flexor digitor sublimis and prof undus; finally, 

 it passes between the tendons of flexor, digit, sublim. and carpi 

 radialis behind lig. carpi volare proprium to the hollow of the 

 hand, where it divides into four branches. 



Branches to: art. interossea, to the hollow of the hand (r. cuta- 

 neus longus) [or palmar cutaneus], and to all muscles of the flexor 

 side of the fore-arm, except flexor carpi ulnaris. 



a. Ram. volaris internus, supplies the skin of the hollow of the 

 hand, the third lumbricalis [sometimes], and the collateral 

 surfaces of the third and fourth fingers. 



b. Ram. medius internus, supplies the second m. lumbric., and 

 the collateral surfaces of the second and third fingers. 



c. Ram. medius externus, supplies the first m. lumbric., and 

 the collateral surfaces of the second and first fingers, and the 

 external of the last. 



d. Ram. externus, muscular branches for flexor, brevis, abduc- 

 tor, and opponens pollicis. 



[e. Ram. interosseus, accompanying the art. inteross. ant., sup- 

 plies the pron. radii quad.] 



7. N. radialis s. spiralis, in size and course resembling the 

 median, arises from the fifth to the eighth cervical nerves from the 

 posterior part of the plexus. Course: it winds round the posterior 

 surface of the upper arm outwards, forwards, and downwards 

 towards the fore-arm, as it passes down upon the anterior internal 

 surface of condylus externus, and divides at the flexure of the arm. 

 Position : at first behind art. axillaris, and separated by it from 

 n. ulnaris and medianus, then close to the bone in a sulcus be- 

 tween the heads of the triceps m., finally passing out obliquely 

 between brachialis internus and supinator longus over the con- 

 dylus externus. 



Branches : a long cutaneous branch, which reaches down as low 

 as the back of the hand, and to all the extensor muscles, except m. 

 extensor carpi ulnaris [?]. 



a. Ram. dorsalis s. ram. super ficialis, continuation of the trunk, 

 passes (on the outer side of art. radiafc) under supinator lon- 

 gus upon the dorsal surface of the fore-arm, perforates the 

 fascia below its centre, and divides into an external and in- 

 ternal branch. 



a. Ram. anterior, passes down upon the extern, pollic. 



brevis, gives branches to the volar surface of the skin of 



the ball of the thumb, and terminates as n. dorsal. 



radialis pollicis on that organ. 



(3. Ram. posterior, supplies the dorsal side of the collateral 



