







Ciliary Body and Processes. (Fig*. 6, 1; 9, d, r.)V\toa the com- extensible sheath called bum luucona; thcnco spreading into n thin 



praued Ulterior surface of the vitreous humour when it ciirvea fan-like expansion, it n reflected obliquely backwards IMI 



inward* from the aclerotio towards the lens, rests the cUiary body, a between the globe and the tendon of the rectus superior (a), :m>! i - 



thin, dark, annular band, about the fifth part of mi incB in brea 1th, inserted into the back part of the sclerotic at a point (m) iut.-r- 



consisting of a frill of flat converging plaiU, which encircle but do mediate between the optic nerve and the insertion (A) of the rectos 



not reach the circumference of the Tens. The posterior aspect is extern u*. and nearer the former. IU separate action turns the 



concave, and adheres loosely over the rounded vitreous humour ; the pupil downwards and outwards. The inferior oblique (/) arises 



front is convex, and is firmly attached to the whole breadth of the broad within the lower edge of the orbit towards the nasal or 



ciliary ligament, and to a small portion of the back of the iris near inner side, and passing obliquely backwards over the tendon of the 



its junction with the ligament. It appears to be a continuation of rectus inferior (&), is attached to the sclerotic at the outer and back 



the inner layer of the choroid, or tunic of Ruysoh, but is rather part opposite the insertion of the trochlearis. It directs the pupil 



thicker, and resembles it in extreme vascularity. The medullary upwards and outwards, supposing the eye to look originally xtraight 



matter of the retina terminates, as we have seen, at the indented forwards : if the pupil be inclined either way, to the nose or to 



posterior margin (ora serrate) of this membranous band. The ciliary the temple, the inferior oblique increases that inclination, being 



body is everywhere thickly coated and pervaded with pigment, except equijwised as to lateral action when the eye is slightly turned inwards, 



at the extremities of about seventy minute unattached points which ' as in reading. But its tendency is always to turn the pupil upwards, 



fringe the inner margin, and radiate towards the lens like the florets To a certain extent the same remark is applicable (mutatis mutandis) 



of a marigold round its central disc. These are the ciliary processes, to the action of the antagonist muscle, the superior oblique, which 



(F iffi. 5, t ; 9, e.) They are separated from the uvea by the fluid of if exerted at the same time would counteract the tendency upwards, 



the posterior chamber, and are received behind into corresponding so that both taken together would keep the eye in that easy position 



depressions in the vitreous humour. so often assumed by man and animals in looking without much 



Appendages of the Globe. The Eyeball, of which we have thus effort yet steadily at near objects, as in taking food, reading, and 



described the contents, is lodged in the cavity of the orbit, a little moat other quiet occupations. The position we mean is that in 



nearer the inner than the outer side. In front, where the protection which the axes of vision are directed slightly towards each other 



of bone is wanting, the two moveable and muscular eyelids supply and a little downwards, and the eyeballs are gently pressed against 



a sufficient defence, and contribute, by their gentle and constant the lida and by them, and thus are kept in a convenient and steady 



pressure, to keep the eye in that state of equilibrium between 

 opposite forces upon which the steadiness and precision of its rapid 

 motions in a great measure depend. The space in the socket not 

 occupied by the globe and its appendages is completely filled by a 

 cushion of soft fat, contained ill elastic membranous cells, which 

 permits the free movement of the several parts, while it keeps them 

 separate, and affords them all, as well as the globe itself, a suitable 

 and uniform support Varieties in the quantity of this substance, 



equilibrium. When the oblique muscles act together with force, they 

 hold the eyeball firmly against the lids and to the nasal side of 

 the orbit. One or both of these muscles, an well as the rectus 

 externus, are supposed to be endowed with certain automatic at 

 involuntary actions, very useful in the economy of vision. Their 

 functions in this and other respects have given occasion to much 

 curious disquisition. 



The Eyelids or Palpebnc. (Pigs. 11, 12; 13.) The textures which 



in the capacity of the orbit, and in the development of the lids, enter into the composition of the eyelids are included between a 

 determine the different degrees of prominence and of apparent size ' soft external skin and a moist smooth internal surface, called the 

 observed in the eyes of different persons; for the globe itself is conjunctiva palpebrolis or proprio. (Fly. 13, o a.) The latter is a 



nearly of the same size in all. 



membrane of the mucous kind, which, as we have already mentioned, 



Muscles of the Eyeball. The movements of the globe are effected after lining the interior of the lids, passes across in a loose circular 



by six muscles arising from the bony surface of the orbit, and scroll or fold to the sclerotic, and is reflected bock again over the 

 inserted into different parts of the sclerotic. Four ore called recti, , front of the eye, where it is called the adnata or conjunctiva reflexa. 



that is straight or direct muscles; the fifth and sixth are the obliqui The name is derived from the junction thus effected between the 



superior and inferior, so called from the obliquity of their insertion, ocular and palpebral surfaces. The outer skin of the eyelids, which 



and their respective positions above and below the globe. The fifth, is extremely soft and delicate, yet capable to a considerable extent 



or superior oblique, is also called the trochlearis, from the trochlea, of adapting itself to different degrees of extension, is loosely con- 



or pulley, through which the tendon passes. 



nected to the subjacent parts, except at the margin (where it adheres 



The recti (fig. 10, a, b, c, d,) are four flat ribbon-like muscles, each I more closely), by a moist and abundant cellular tissue, entirely devoid 

 about half an inch broad, which arise together round the edge of ! of fat. By means of this connection, when the upper lid is raised 



the foramen opticum, and 

 embrace the nerve at its exit 

 from the skull. They end in 

 brood thin glistening tendons, 

 attached to the sclerotic at four 

 equidistant points, about a 

 quarter of on inch from the 

 edge of the cornea, above, 

 below, and on cither side. 

 Hence they are designated ns 

 the superior, inferior, internal, 

 and external straight muscles. 

 We have already explained bow 

 the outer surfaces of their ten- 

 dons ore blended, and form the 

 tunica albuginea. Each turns 

 the pupil towards the side of 

 iU insertion ; and it is easy to 

 Me how by their single actions, 

 or by a proper combination of 



Fig. 10. 



and these under-lying parts are 

 retracted under the edge of the 

 orbit, the superfluous skin is 

 gently drawn after them, and 

 is disposed of conveniently 

 under the brow (supercilium). 

 The eyelids meet, when closed, 

 by two narrow flat surfaces, 

 accurately applied to each 

 other, called their ciliary or 

 tarsal margins. These epithets 

 are respectively derived from 

 the tarsi, or thin concave and 

 crescentic shells of smooth and 

 elastic cartilage which give 

 form to the lids, and firmness 

 and outline to their opposed 

 edges (fig. 10, I); and from 



_ the lashes or cilia, which grow 



Lateral view of the rirht eyeball, seen from the oatr ,Mr, with Its mcl. (Thi. "J >veral rows at the margins 



two that are contiguous, the cul ,, , ^ cmuUmi ,,,... . di.ffr.rn. the proportion, of the part, having been of both llds ' fro1 * the ' r 



pupil may be turned in any much a n cr oU to make them more distinct.) treme outward verge, and in 



required direction. The rectus 0> mlm , upcrlor . , rec tu. Inferior ; c, reetus intcrnus ; d, recta. OXUNIIIS, aririn* the diction of the flat sur- 



ius.fr 00 on u)r double head (It li repreicntrd u cut off from A, IU Insertion into the eyeball, 'aces. "he angles in whi.-h 



the diverging side of the orbit, and turned xide to .bow the parti behind II); r, obliquun superior, n round ami the margins of the eyi-li.h 



is necessarily the longest of tapering muwle terminatinu ir. a round tendon, which pane, through a pulley or loop meet towards the nose and 



these muscles. It hits also a (*), and U reflected under the flat tendon of the rectus luperlor, and, bccnming flat, in temple arc called the canthi. 



double origin, mixing not only inaerlcd at (m) Into the Klcrotlc; /, obllquui Inferior coming round over the tendon of The outer canthus is kept in 



in common with the rest from tllc rrcla * Mntor from the front and inner edge of the orbit, near the inner corner of jt, ]^^ duria the motions 



in common with the rest from lc rrca * nr rom e ron an nner ege o te orbt, near the inner corner o jt, p]^^ 

 the rdgc of the optic foramen, "'' *>"' ni1 i"*"-ted Into the Mlcrotlc O|,po..lt<- the inwrtlon of the superior oblique ; f t p 



, f zJe' Id" % - -- ^ ,!:, ;":; &% ;;r, s? s: a- 



duriag the motions 

 ex- 



which - 



si on the 



enter the orbit by that passage ' or" convex surface, attaches 



I ;<). The superior oblique or tochlearis () U a round tapering them, and most closely on this (the temporal) side, to the margin 



muscle, which arises near and on the nasal side of the rectus of the orbit It is called the broad ligament of the tarsi. The nasal 



inU-rnus (r), and ends in a smooth round tendon. The pulley (k) extremities of the tarsi are confined to the side of the nose by two 



through which this tendon passes is a small loop of cartilage fixed slips which are given off behind from the tendon of the orbicular 



to the roof of the orbit toward* the nasal side, just within the muscle, 



margin. In this situation the tendon is enveloped in a lubricated Muscles of the Eyelids. Immediately beneath the subcutaneous 



