THE OPHTHALMIC NERVE. 221 



''The ophthalmic nerve, after running between the 

 rectus superior and the retractor muscles, gives a 



the more numerous. They pass between the choroid membrane 

 and the contiguous sm-face of the sclerotic — lodged in grooves in 

 the latter — and on reaching the ciliary lig-ament, pierce it, a few 

 appearing to be lost in its substance, while all the rest pass in- 

 ward and ramify in the iris. From the posterior border of the 

 ganglion, which seems as if terminated by two angles, two 

 branches issue, one of which passes backward and upward to 

 the nasal branch of the ophthahnic nerve, appearing to be the 

 medium of communication between the ganglion and the rest of 

 the ganglial system, by being prolonged to the carotid plexus. 

 The other, the shorter branch, passes downward and backward 

 to the inferior oblique branch of the motor nerve of the eye.' 



" For my own part," says Prof. Youatt, " I am now disposed 

 to be very much of Dr. Quain's opinion. It was not fittin<T that 

 the motions of the iris should be under the control of the will — 

 they should respond to the varying intensity of the light." — W. 

 Touatt in " Vderinnrian" for IS JO, p, 49. 



Mons. Cuvier says : " It divides into two ramifications, one of 

 which proceeds toward the optic, unites with the small branch 

 of the third pair, and by this union produces a nervous enlarge- 

 ment called the lenticular or ophthalmic ganglion. This jran- 

 fflion usually sends off the ciliary nerves, disposed in two bun- 

 dles. They are each composed of several filaments, which enter 

 the globe of the eye obliquely. The iris receives a great num- 

 ber of small ramifications from the ciliary nerves, which, after 

 having perforated the sclerotic and passed around the choroides 

 longitudinally, like ribbons, but %vithout penetrating it, are lost." 

 — " Comparative Anatomy" Vol. II, p. 306. 



Prof. W. Percivall says: " Upon the outer side of the optic 

 nerve, between it and tliat part of the motor oculi from which 

 the branch nerves spring, is situated the ophthalmic ganglion. 

 This little body is principally^ constituted of branches from the 

 third pair, but it receives a filament or two from the sixth. The 

 nervous threads transmitted by the ganglion surround the sheath 

 of the optic nerve, and pursuing their course over it, penetrate 

 the globe of the eye, and run to be dispersed upon the iris." — 

 "Anatomy of the Horse," p. 336. 



