168 



Anatomy of the Rabbit. 



(b) The vascular tunic (tunica vasculosa oculi), the thin middle 

 coat of the eye; pigmented, except in albino animals. It is 

 divisible into : (1) a general portion, the chorioidea, lying on 

 the inner surface of the sclera; (2) a muscular portion, the 

 ciliary body (corpus ciliaye), forming an annular ridge about 

 the periphery of the lens ; and (3) the iris, the latter forming' 

 a circular fold suspended about the periphery of the lens and 

 on its outer surface. 



(c) The retina, the innermost layer of the eye, forms a thin soft 

 membrane covering the inner surface of the chorioidea. It 

 is divisible in a larger optic portion, the sensory part of the 

 eye, and a smaller ciliary portion, lying about the periphery 

 of the lens and distinguishable by the radiate markings of 

 its surface, the latter formed by the projecting ridges of the 

 ciliary body. 



(d) The transparent lens of the eye is suspended by fine filaments, 

 the zonular fibres, reflected from the margin of the ciliary 

 body. 



(e) The vitreous body (cor- 

 pus vitreum), a trans- 

 parent mass, of gela- 

 tinous consistence, 

 occupies the large space 

 enclosed by the lens 

 and the retina. 



(f) The space enclosed 

 between the surface of 

 the lens and the cornea 

 is divisible into a larger 

 portion, the anterior 

 chamber (camera oculi 

 anterior), lying outside 

 of the iris, and a smaller 

 portion, the posterior 

 chamber (camera oculi 

 posterior), lying be- 

 tween the iris and the lens. The central space enclosed 

 by the free margin of the iris is the pupil (pupilla). 



12. Following the removal of' the eye, the bloodvessels and nerves 

 of the orbit may be freed from the remaining portions of the eye muscles 

 and examined. In order to see their connections in the anterior angle 

 of the orbit, it is necessary to break away the anterior root of the zygo- 

 matic arch, and also the bony ridge which lodges the alveoli of the pos- 

 terior cheek-teeth. 



(a) The internal maxillary artery enters the orbit through the 

 anterior sphenoidal foramen in the root of the lateral lamina 

 of the pterygoid process. At the posterior ventral angle of the 

 orbit it gives off the inferior ophthalmic artery (a. ophthalmica 



Frc 50. Diagram of the parts of the eye in 

 vertical section: c.a., anterior chamber; c.c. 

 ciliary body; ch., chorioidea; co., cornea; c.p., 

 posterior chamber; c.r., ciliary portion of the 

 retina; c.y., vitreous body; d.h., Harderian duct; 

 d.l., position of the lacrimal ducts; d.n., nasola- 

 crimal duct; i., iris; 1., lens; n.o., optic nerve; 

 o.r., optic portion of the retina; p.i., lower 

 eyelid; p.s., upper eyelid; p.t., third eyelid; 

 r.b., retractor bulbi; r.i., rectus inferior; r.s., 

 rectus superior; sc, sclera; z., suspensory 

 zonular fibres of the lens. 



