THE CRYSTALLINE LENS 1111 



The ciliary veins are seen on the outer surface of the choroid, and are named from their 

 arrangement, the venae vorticosae (p. 1095). They converge to four or five equidistant trunks, 

 which pierce the sclera midway between the margin of the cornea and the porus opticus. An- 

 other set of veins accompanies the anterior ciliary arteries and opens into the ophthalmic vein. 



The Lymphatic Passages of the Eyeball. The conjunctiva contains -lymph vessels. 

 The eyeball contains lymph spaces, but no lymph vessels. There are two sets of lymph spaces 

 in the eyeball, the anterior and posterior. The anterior lymph spaces are the spaces of the 

 cornea, of the iris, of the anterior chamber, and of the posterior chamber. The lymph from the 

 intralamellar lymph spaces of the cornea enters the conjunctival lymphatics at the margin of the 

 cornea. The lymph spaces of the iris open into the anterior chamber by the crypts of the iris, 

 and at the margin of the iris join the spaces of Fontana. The aqueous humor fills the anterior 

 and posterior chambers, but is furnished by the vessels in the posterior chamber; in part by the 

 vessels of the ciliary body, and in part by the vessels of the posterior surface of the iris. The 

 lymph passes by way of the pupil into the anterior chamber, and then is taken up by the spaces 

 of Fontana, the canal of Schlemm, and the anterior ciliary veins. 



The posterior lymph spaces are the hyaloid canal, the perichoroidal lymph space, the space 

 of Tenon, the intervaginal space of the optic nerve, and the supravaginal space. 



The hyaloid canal (Figs. 794 and 797) passes between the posterior surface of the lens and the 

 optic disk. The hyaloid canal opens into the intervaginal space of the optic nerve. Between 

 the sclera and the choroid is the perichoroidal lymph space (Fig. 820). It is around the choroid 

 vessels and the venae vorticosae, and empties into Tenon's space by means of openings through 

 the sclera about the venae vorticosae. Te'non's space (Figs. 794 and 795) is between the sclera 

 and the capsule of Tenon. It receives lymph from the perichoroidal space, and empties into the 

 supravaginal space. 



The optic nerve (Fig. 811) has a sheath of dura and a sheath of pia, and between these sheaths 

 is the intervaginal lymph space. It is divided by a prolongation of the cerebral arachnoid into 

 a subdural space and a subarachnoid space, which empty into the corresponding spaces of the 

 membranes of the brain. The supravaginal space is between the dural portion of the sheath 

 of the optic nerve and a posterior prolongation of Tenon's capsule. 1 



The Nerves of the Globe of the Eye. The long ciliary nerves (nn. ciliares longi)^siQ 

 in number, are derived from the nasal branch of the ophthalmic, and the short ciliary nerves 

 (nn. ciliares breves), twelve to fifteen in number, are derived from the ciliary or ophthalmic gan- 

 glion. Both the long and short ciliary nerves perforate the sclera in the neighborhood of the 

 optic nerve (Fig. 801). They pass along the perichoroidal Ivmph space, forming a plexus 

 which sends filaments to the choroidal vessels. In front of the Ciliary muscle they form a second 

 plexus, and from it come branches which go to the Ciliary muscle and the muscle fibres and 

 vessels of the iris, sclera. chprpid, ciliary body, and iris (F'ig. 808). The ciliary nerves supply 

 the cornea. The circular "fibres of the iris are innervated by the oculomotor nerve and the 

 radial fibres bv the sympathetic. 



Applied Anatomy. From a surgical point of view the cornea may be regarded as consist- 

 ing of three layers: (1) Of an external epithelial layer, developed from the ectoderm, and con- 

 tinuous with the external epithelial covering of the rest of the body, and therefore its lesions 

 resemble those of the epidermis; (2) of the cornea proper, derived from the mesoderm, and 

 associated in its diseases with the fibrovascular structures of the body; and (3) the posterior 

 elastic layer with its endothelium, also derived from the mesoderm and having the characters 

 of a serous membrane, so that inflammation of it resembles inflammation of the other serous 

 and synovial membranes of the body. 



The cornea contains no bloodvessels, except at its periphery, where numerous delicate loops, 

 derived from the anterior ciliary arteries, may be demonstrated on the anterior surface of the 

 cornea. The rest of the cornea is nourished by lymph, which gains access to the proper sub- 

 stance of the cornea and the posterior layer through the spaces of Fontana (spatia anguli iridis). 

 This lack of direct blood supply renders the cornea very apt to become inflamed in the cachectic 

 and ill-nourished. In spite of the absence of bloodvessels, wounds of the cornea usually heal 

 rapidly. A wound which penetrates the cornea opens the anterior chamber, and aqueous humor 

 escapes. An ulcer may also open the anterior chamber. Through a wound or a perforated 

 ulcer the papillary margin of the iris may prolapse. A trivial injury of the cornea is repaired by 

 transparent tissue. A severe injury is repaired by fibrous tissue, and opacity results. A slight 

 opacity resembling a cloud of gray smoke is called nebula; a more marked white opacity is called 

 leucoma. In abscess of the cornea pus gravitates between the layers to the lower part of the 

 cornea and the purulent collection assumes a crescentic shape (onyx). The arcus semlis, seen 

 in the aged, is a condition of haziness or opacity at the corneal margin due to fatty degeneration 

 of the tissues of the cornea. It signifies interference with the blood supply, because of senile 

 degeneration of adjacent vessels. In cases of trachoma there is a peculiar affection of the cornea, 

 called pannus, in which the anterior layers of the cornea become vasculamed, and a rich network 



1 For the lymphatic channels of the eyeball see Deaver's Surgical Anatomy, vol. ii, p. 392. 



