1064 



SPECIAL SENSE ORGANS 



Histologically the capsule is not in immediate contact with the cortex over the front surface 

 of the lens, a single layer of cells intervening, called the epithelium lentis. 



The zonula ciliaris or suspensory ligament of the lens is formed by a number of 

 fine zonular fibres [fibrse zonulares] passing from the ciliary body. They are 

 attached to the lens-capsule a little in front of and behind the equator, and the 

 spaces included between the fibres of the ligament are termed the zonular 

 spaces [spatia zonularia]. A continuous space, which can be injected after 

 death, round the margin of the lens is known as the canal of Petit. It is probably 

 an artefact. This space is bridged across by fine intermediate suspensory 

 fibres, and is occupied by fluid. 



The vitreous body [corpus vitreum] is a transparent, colourless, jelly-like mass, 

 the vitreous humour, enclosed in a delicate, clear, structureless membrane, called 

 the hyaloid membrane. This latter is closely applied to the back of the posterior 

 lens-capsule and of the suspensory ligament, and to the inner surface of the pars 

 ciliaris retinae, retina proper, and optic papilla. Although possessing some degree 

 of firmness, the vitreous humour contains quite 98 per cent, of water, and has no 

 definite structure. 



Fig. 807. — Blood-vessels of the Eyeball, Lateral View. 



Cornea 



Anterior chamber 



Iris V 



Circulus arteriosus minor 



Circulus arteriosus . 

 major 



Ciliary region " 



Short posterior ^__ 

 ciliary arteries 



Optic nerve 



Arteria centralis retinae ,n. 



^ Sclero-corneal junction 



1 Anterior ciliary artery 



Long posterior 

 ciliary artery 



""-« V. Vorticosa 



Membranes have been described in it, but these are really artificial i)roducts. In certain 

 situations spaces exist in the vitreous mass, the most determinate of which runs in the form of a 

 canal froin the optic papilla to the posterior p()l(> of the lens, corrcsijonding to the position of 

 the fo'tal liyaloid artery (hyaloid canal or canalis hyaloidea). Other very fine spaces are de- 

 scribed ruiuiing circularly in tlu; ])eripheral part of tiie vitreous concentric with its outer sur- 

 face. Microscoj)ically, wandering cells are foiuid in the vitreous, which often here assume 

 peculiar forms whicli the observer can, not infrecjuently, study subjectively. 



The aqueous humour is a clear, watery fluid, occupying the space between the 

 cornea on tlu; one hand, and the ciliary body, zonula ciliaris, and lens on the other. 

 The iris, projecting into this space, has both its surfaces bathed in the a(iueous; 

 but, as its inner part rests on the lens, it is regarded as dividing tiie space into two 

 parts, an anterior larger, and a posterior smaller, aqueous chamber [camera oculi 

 ant(!rior; posterior], which coniinuiiicate freely through the ])ui)il. 



Ciliary nerves of the eyeball. Tlu! long and short ciliary nervc^s, after per- 

 forating the sclera run forward between it and the chorioid to the ciliary region, 



