162 EQUINE ANATOMY. 



The organ of Corti is very intimately connected with the 

 perception of sound. The scala vestibuli is again divided by the 

 membrane of Reissner into two more canals. 



The Fluids of the internal ear are the endolymph, limpid and 

 watery, inside the membranous labyrinth, and the perilymph 

 outside the membranous portion. 



The Nerve Supply is from the eighth or auditory nerve, which 

 splits up into vestibular branches, to the utricle, saccule and ampulla 

 and cochlear branches to the different scalae of the cochlea. 



SIGHT. 



The eyes are two globular bodies, situated in the orbital cavi- 

 ties, that collect impressions of light, these impressions being 

 carried to the brain by the optic or second pair of nerves. 



THE ORBITS. 



Two bony cavities, situated at the upper and anterior part of 

 the face, containing the organs of vision. The bones entering 

 into their formation are at its base the zygoma, the zygomatic 

 process of the temporal, malar, jrontal and lachrymal. 



On the inner side are found the sphenoid, palate and superior 

 maxilla. The orbit is continuous behind, with the temporal 

 fossa. On its inner side, anteriorly, is seen the lachrymal fossa. 



The foramina opening into it are the palatine, spheno-palatine, 

 superior dental, optic, pathetic, lacerated and rotundum. 



THE EYE. 



The organs of vision consist of the two eyeballs and appendages. 



The eyeball is spheroidal in shape, a little longer in its antero- 

 posterior diameter, where it is continued by the cornea. It lies 

 in the fat of the orbit, held in position by its muscles, and con- 

 sists of three tunics surrounding the humors. 



TUNICS. 



The tunics of the eye are the (i) sclerotic and cornea, (2) choroid 

 and iris, and (3) retina. 



The Sclerotic is the white, dense, outer coat into which the 

 muscles are inserted. The choroid lies in contact with it inter- 



