120 On the Sensory Nerves of the Eye-Muscles. 



" Further Note on the Sensory Nerves of the Eye-Muscles." By 

 0. S. SHERRINGTON, M.A., M.D., F.R.S., University College, 

 Liverpool. Received September 21, Read November l*7 r 

 1898. 



In a communication on the sensory nerves of muscles laid before the 

 Society last year,* the question previously raisedf as to the existence 

 of afferent nerve fibres in the so-called " motor " cranial nerves for the 

 muscles of the eye was advanced to the following position. Myelinated 

 nerve-fibres from the Illrd cranial and IVth cranial nerve-roots were 

 traced into the tendons of the recti and oblique muscles. Since then 

 control observations have been made. The ophthalmic division of the 

 Vth cranial has been severed at its origin, and with it the Vlth cranial 

 trunk. This has been done in the monkey. The condition of the 

 nerve branches going to and lying within the muscles and tendons has 

 been examined after an interval of twelve to fourteen days. Those of 

 the external rectus contained nothing but degenerate nerve-fibres, save 

 for a few fine myelinate fibres, probably from the ciliary ganglion. 

 Those of all of the other eye-muscles contained exclusively healthy 

 nerve-fibres. The sensorial musculo-tendinous organs of the eye-muscles 

 are, therefore, not innervated by the ophthalmic division of the tri- 

 geminus. On the other hand, the nerve-fibres of the external rectus 

 muscle behave, after severance of the YIth cranial nerve, in the same 

 way as my previous papers showed those of the other eye muscles do- 

 after section of the Illrd and IVth nerves. 



A contribution towards the physiological inquiry into the matter has 

 been made as follows, and has given a clear reply. The conjunctives, 

 both palpebral and ocular, and the corneas of both eyes have been ren- 

 dered deeply anaesthetic to cold, warmth, touch, and pain by liberal 

 applications of cocaine. Then in a completely dark room the power to- 

 direct the gaze with accuracy in any required direction has been tested. 

 The person under examination is seated, with the head securely fixed, 

 in front of a screen. One of his hands carries a marker. The hand is 

 moved by an assistant, and is made to mark the screen at some one 

 point ; it is then passively replaced. The person under observation 

 during this time keeps the eyes open in the primary position or sits 

 with them closed. He is then required to direct his gaze to the spot 

 marked on the screen. The light is then switched on, and the point to 

 which the gaze is turned is noted. The power to direct the gaze under 

 these circumstances has been found to remain good. If for co-ordinate 

 execution and ability to perform the delicate adjustments for training 



* C. S. Sherrington, ' Roy. Soc. Proc.,' vol. 61, p. 247, February, 1897. 

 f C. S. Sherrington, ' Pliysiol. Soc. Proc.,' No. 3, June, 1894. 



