CHAPTER XII. 



THE TRIGEMINUS OR FirXH PAIR OF SERVES. 



Its Nature aud the Relation it "bears to tlie Teeth. — Its Coui'se in 

 tliG Horse and in Man. 



The thread-like nerves of the teeth are derived from 

 the superior and inferior maxillary branches of the 

 trigaminiis or hfch pair of nerves. In the horse thess 

 branches are four or five times as thick as a ribbon 

 and about five-eighths of an inch v.'ide. The ophthal- 

 mic branch is smaller and shorter, its course extend- 

 ing only from the brain to the eye, while that of the 

 two former extends to the lips, running parallel to and 

 about an inch from the roots of the grinder teeth.* 



The description of the trigeminus and its course is 

 from a lecture by Prof. Youatt to veterinary students, 

 and may be found in '-'The Veterinarian" for 1834 

 (p. 121). In the first part of the lecture the nature of 

 the trigeminus— its double origin and function's 

 expatiated upon, a summary of which is that tlie sensi- 

 tive and motor roots, are contained within the same 

 sheath ; that the sensitive root is so mucli larger and 

 its fibrils so much more numerous than tlie motor that 



* For tlie preparation of an anatomical specimen sliowinc; tlie 

 j^eneral course of the trif^ominns, I nm indebted to Prof. J. M. 

 Heard, of the New York College of Veterinary Surgeons. 



