XERVES OF THE FOREARM. 67 



d. The dorsal cutaneous nerve of the hand (fig. 23, p. 57) leaves the cutaneous 

 trunk al >out two inches above the end of the ulna, and passes obliquely jjve of 

 backwards beneath the flexor carpi ulnaris ; perforating the aponeu- hand. 

 rosis, it is distributed on the back of the hand and fingers (p. 58). 



The MEDIAN NERVE (fig. 26, 1 ) leaves the hollow of the elbow Median 

 between the heads of the pronator teres, and runs in the middle JJtJreenthe 

 line of the limb to the hand. It is placed beneath the flexor two groups 

 sublimis as low as two inches from the annular ligament, where it of muscles - 

 becomes superficial along the outer border of the tendons of that 

 muscle. Lastly, the nerve passes beneath the annular ligament to 

 the palm of the hand, and its position in this part may be marked 

 011 the surface by the tendon of the palmaris longus. It supplies 

 the muscles on the front of the forearm, and furnishes a cutaneous 

 offset to the hand. 



Muscular offsets leave the trunk of the nerve near the elbow, and it supplies 

 are distributed to all the superficial muscles except the flexor carpi JJ^SJ* 

 ulnaris ; in addition the nerve supplies the deep layer of muscles except one 

 through its interosseous branch (p. 69), except the inner half of andahalf > 

 the flexor profundus digitoruui. 



The cutaneous palmar branch ( 3 ) arises in the lower fourth of the and a branch 

 forearm ; it pierces the fascia near the annular ligament, and crosses j ^J 1111 of 

 over that band to reach the palm (fig. 15, p. 39). 



The RADIAL NERVE is the smaller of the two branches into which Radial nerve 

 the niusculo-spiial divides at the elbow. This nerve is placed along to for earm. 

 the outer border of the limb, under cover of the supinator longus 

 and on the outer side of the radial artery, to the junction of the 

 middle and lower thirds of the forearm, where it becomes 

 cutaneous at the posterior border of the supinator tendon. It finally it ends on 

 divides into two branches, which are distributed on the dorsum of JjjJ of the 

 the hand and digits (fig. 23). No muscular offset is furnished by 

 the nerve. 



Dissection (fig. 26). To examine the deep layer of muscles it Dissection 

 will be necessary to draw well over to the radial side of the forearm of de P 

 the pronator teres, to detach the flexor subliinis from the radius, and 

 to remove its fleshy part. A thin layer of fascia, which is most 

 distinct near the wrist, is to be taken away ; and the anterior 

 interosseous vessels and nerve, which lie on the interosseous mem- 

 brane, and are concealed by the muscles, are to be traced out. 



Over the bones at the lower end of the forearm the arch of the show carpal 

 anterior carpal arteries may be defined. arch - 



DEEP GROUP OF MUSCLES. There are three deep muscles on the Three mus- 

 front of the forearm. One, covering the ulnar, is the deep flexor of ^ es ^^ e 

 the fingers ; a second rests on the radius, the long flexor of the 

 thumb ; and the third is the pronator quadratus, which lies beneath 

 the other two, over the lower ends of the bones. 



The FLEXOR PROFUNDUS DIGITORUM (flexor perforailS, fig. 26, C) Deep flexor 



9 from the anterior and inner surfaces of the ulnar for three- of 

 fourths of the length of the bone (fig. 25, p. 60), from the inner half ongin ' 

 of the interosseous ligament for the same distance, and from the 

 aponeurosis of the flexor carpi ulnaris. The muscle has a thick 



F 2 



