428 



Mr. W. P. Herringliam. 



and 9th. But these roots do not send to it a constant proportion. 

 There is little variation in the size of the 6th bundle, the 7th varies 

 considerably, the 8th is sometimes equal to, sometimes smaller than, 

 and sometimes larger than the 9th. 



The 6th bundle runs down the outer side of the nerve from the top 

 to the bottom, though in dissection the nerve generally becomes so 

 twisted that it seems otherwise. In the lower third of the arm a pair 

 of fibres are seen crossing from the outer to the inner side. These 

 are the nerves to the pronator teres and the flexor carpi radialis. 

 They are given off: almost always by the 6th, and they usually run 

 over in front of the nerve to reach the muscles. 



I have, however, dissected them running through the nerve and 

 separating the other bundles. The nerve to the pronator usually 

 divides into two before it reaches the muscle, and is sometimes double 

 from the beginning. With the nerve to the flexor carpi radialis runs 

 a nerve to the other flexors, but this comes from a lower root. In 

 eight cases where the 6th and 7th were not separated, these two 

 muscles were supplied by the combined bundle. The nerve to the 

 pronator teres was traced seventeen times to the 6th, once to the 7th ; 

 that to the flexor carpi radialis thirteen times to the 6th, tw^ice to the 

 7th ; neither to any other nerve. The 6th does not supply any other 

 muscles in the forearm. 



The 7th was traced nine times to the flexor sublimis, and in four 

 of these it also contributed to the anterior interosseous. It is to be 

 noted that in two of these four it also formed part of the ulnar. Of 

 the five cases when it did not go to the anterior interosseous the ulnar 

 was traced in four, and did not in any of these receive from the 7th. 

 Where then the 7th goes to the anterior interosseous it is probable 

 that it will form also part of the ulnar ; when it is excluded from the 

 ulnar it probably does not contribute to the anterior interosseous. In 

 seven cases no branch could be traced to the flexor sublimis. 



The 8th and 9th usually supply the flexor sublimis, and always the 

 deep flexors. In seventeen instances the flexor sublimis received 

 from them fourteen times, and three times did not receive from them. 

 The two nerves were separated six times in adults, with the result 

 that they seemed to mingle in all muscular branches in the forearm, and 

 that no muscle could be said to belong to the one and not to the other. 



After the forearm muscles have been supplied, the remainder of 

 the median which comes from under the flexor sublimis always con- 

 tains fibres from the 6th, 7th, and 8th roots, and sometimes a bundle 

 from the 9th. 



The 6th was traced separately eleven times, and the 7th seven 

 times in this part of the nerve. Neither was ever found absent. The 

 distribution of the lower two roots in the hand was traced in eleven 

 cases. In six of these they were not separated ; in the other five the 



