84 



LACRYMAL ORGANS. 



and continuation with each other of these two 

 portions of the membrane. It is by this conti- 

 nuity that the eyelids and eyeball are held in 

 connexion, hence the name conjunctiva, and 

 that the orbit is closed in and cut off from 

 all communication with the space between the 

 eyeball and eyelids. 



The space between the eyelids and eyeball we 

 shall distinguish by the nameof oculo-pulpebral 

 space of the conjunctiva, a name, the necessity 

 for which appears from this, that in common 

 language, when it is said a foreign body has 

 got into the eye, it is only meant that it has got 

 into the oculo.-palpebral space of the con- 

 junctiva. The propriety of the name moreover 

 will become more evident when the space in 

 Serpents and Geckoes comes under considera- 

 tion, for in them it is a closed cavity, (in ser- 

 pents already designated by Jules Cloquet* 

 oculo-palpebral sac of the conjunctiva,) re- 

 ceiving the lacrymal secretion and communi- 

 cating with the exterior only by the connexion 

 it has with the nose through the nasal duct. 



What are called the superior and inferior 

 palpebral sinuses of the conjunctiva are those 

 parts of the oculo-palpebral space under the 

 upper and lower eyelids respectively, where 

 the ocular and palpebral portions of the con- 

 junctiva are reflected and continued into each 

 other, forming a cul-de-sac. The conjunctiva 

 is here loosely attached to the subjacent cellular 

 and adipose tissue, &c. of the orbit, and forms 

 folds constantly varying with the motions of the 

 eyeball and eyelids. The superior palpebral 

 sinus of the conjunctiva is deeper than the 

 lower, the reflection of the conjunctiva from the 

 eyelids upon the eyeball being svhen the eyelids 

 are passively closed : above, at the distance of 

 about seven-tenths of an inch from the margin 

 of the upper eyelid, and below, at about three- 

 tenths of an inch from the margin of the lower. 

 The cul-de-sac formed by the reflection of the 

 conjunctiva does not lie very deep within the 

 outer canthus, speaking in reference to it alone, 

 though as near the edge of the orbit as above or 

 below. 



The looseness of the folds formed by the 

 conjunctiva at the upper and lower palpebral 

 sinuses and within the outer canthus, together 

 with the peculiar nature of its disposition at 

 the inner canthus, presently to be noticed, allows 

 of the free motions of the eyeball in all direc- 

 tions. These folds may be readily seen on 

 everting either eyelid, as also the continuity of 

 the conjunctiva from the eyelid to the eyeball 

 by requesting the person to look upwards, if it 

 is the lower eyelid which is everted, downwards 

 in the contrary case. 



In operations on the eyeball when the eyelids 

 are held apart unskilfully, the folds are thrust 

 out between the eyelids by the action of the 

 orbicularis muscle, so that they almost bury 

 the front of the eyeball and consequently im- 

 pede the operator. 



By long-continued catarrhal ophthalmia and 

 the abuse of blue stone and similar escharotics, 



* Memoire sur 1'existence et la disposition des 

 voies lacrymales dans les screens. IVris, 1821. 



the conjunctiva is apt to become contracted and 

 thickened, and to acquire at the same time a 

 callous articular surface. In such cases the 

 contraction tells very much upon the looseness 

 of the folds of the conjunctiva at the upper and 

 lower palpebral sinuses, which may indeed be 

 said to be obliterated. The consequence of 

 this is great restriction in all the movements of 

 the eyeball. 



Foreign bodies which may have entered the 

 oculo-palpebral space sometimes get lodged 

 in the palpebral sinuses of the conjunctiva, 

 especially the upper, and may he retained there 

 for a length of time without causing much or 

 any irritation, the conjunctiva being there so 

 loose and the adjacent cellular and adipose 

 tissue of the orbit so soft that the body is not 

 much pressed upon by the opposing surfaces. 

 The contrary is the case when the foreign body 

 lies between the eyeball and the hrm part of 

 the eyelid, for here its irritation excites the 

 orbicularis muscle to stronger action which 

 serves but to aggravate the distress. 



Disposition of the conjunctiva at the inner 

 canthus. Under this head falls to be consi- 

 dered the semilunar fold, the notice of which 

 it will be advantageous to premise by a descrip- 

 tion of the lacrymal caruncle. In consequence 

 of the prolongation of the palpebral fissure at 

 the inner canthus into a secondary one, the 

 lacrymal caruncle and semilunar fold are so 

 exposed that their external conformation can 

 be readily and indeed best studied in the living 

 eye. 



Lacrymal caruncle, carunculu lacrymalis. 

 Fr. La caroncule lacrymale. Ital. La carun- 

 cula lagrimale. Germ. Die ThrdnenkanmkeL 

 Tnis is a small reddish yellow eminence having 

 a slightly tuberculated surface, beset with very 

 delicate scarcely visible hairs. It is situated, 

 as has been said, within the secondary fissure 

 of the inner canthus, and inclosed between the 

 two slips of the tendo palpebrarum. To see 

 the lacrymal caruncle in its whole extent, it is 

 necessary to evert slightly the lower eyelid, 

 when it is observed running into a point down- 

 wards and outwards. The lacrymal caruncle 

 consists of a mass of loose fibre-cartilaginous 

 tissue, similar to that of the tarsal cartilages, in 

 which are imbedded follicles, secreting a fluid 

 of the same nature as that of the Meibomian 

 glands, and pouring it out by twelve or fifteen 

 excretory orifices on its surface, which is in- 

 vested by the conjunctiva. Anciently the la- 

 crymal caruncle was thought to be the secreting 

 organ of the tears, and the lacrymal points the 

 excretory orifices. 



Semilunar fold, plica semilunaris. Fr. Le 

 repli semilunaire. Ital. La piega semilunare. 

 Germ. Die halbmondjormigen Falte. In passing 

 from the caruncle to the eyeball, the conjunctiva 

 forms a vertical semilunar fold which encloses 

 at its free edge a minute cartilage of a nature 

 similar to the tarsal cartilages. This part of 

 the conjunctiva is distinguished from the ocular 

 portion by its reddish colour and greater thick- 

 ness, indeed it resembles more the palpebral 

 conjunctiva than the ocular. The concavity of 

 the crescent, which is also the free edge of the 



