Page:Cyclopaedia, Chambers - Volume 1.djvu/743

 EYE

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EYE

(KWimhefer in 1308; and Fa. Mabillon, AS a SanS. Brain alone with the Omi, >t

WS.&MIt.pii W^J&gemetlnaionU faid to be irlved fern £ bS^? M*- •"»* *

now Mg», aS the Divines call it; formerly 'twas ab- being an Expanfion of the medulla™ fin* " fe i f >? 3

folu.-e and indicative. OntS ic;.*. R„» .,,-1, t...:.?"' '?. r y . Subftance of the

EXTRINSIC, is applied in the Schools in various S3* ££JSL^ T ^__ d ^bed under nfes. K0ID

Sometimes it figmfies a Thing's not being of the Effencc Pupilla

Senfes.

Article, Conjunctiva, Sc« M M c„ ,tS P'°P er Roides, Uvea, and Retina. Sec <?£»"» G »°;

PuPILLA. all ° U " alld

The ffsjawBj»j of the Eye, inclofed between thefe Tunics, are three.- w. P. The ,%«««, a j; ^ the ' e Iparent Humour, fituate in the fore-part of the F„ :„ mediately under the Cornea, and occasioning ite Mil berance. a°. The Cryftalline, fituate immediately under . 4? mms ' behind the ^^ oppofite to the Bnpil 5 • J he Various, or Glafly Humour, which fills all the' hmd-part of the Cavity of the Globe 5 and is that

bacl P S 'r- the /P herical Fi g ure t0 the -$»■ °n N nacK lart ,s the iJmVa fpread. See each Humour

Viraio* Pr ° Per Article ' Aqjieous, Crystalline, and

per S Memb Uth ° K i, fincling thefe Humours c ° v « y with pro-

TheWord is compounded of the Latin ex and uben Aqueous, Cn/iallTneKll ' 5^! a N i. me? t0 * e »; * *e

plentiful, of „fc,, Udder. ]J only ' Pro£ffit ' of rhf T" r"T I bUt '" >T

EXUIXERATION, in Medicine, the A3 of occafion- the Diftinflio n is not LI W J f °* abovementlon d >

ing, or producing Ulcers. See Ulcer. The F e /WA ^?/ „ » S ^ „,,.

Thus, Arfenic • Exulcerates the Ir.teftines: Corrofive and VeinsT f JS * K NemS > Glmis > Arterie *i

Humours Exulcerate the Skin. ,■ The ».„,. . a, „. „, ,

The Term is fometimes alfo ufed for an Ulcer it fitfj a Perforation i Tw C h'^i which iflhing thro'

but more generally for thofe beginning Erofions, *hi^ Ball of the F V e and diff ,V„ f i, r \ 2frf' "f - the

wear away the Subflancc, and form Ulcers. _ Exultations the outer CoX' -oi-'j uc" 1 T the .n*lves therein;

of another; in which Scnfe the efficient Caufc, and the End or Scope of a Thing, are faid to be Extrinfic, or Extrinfic Caufes. Sec Cause.

Sometimes it implies a Thing's not being cbntain'd within the Capacity of another; in which Senfe thofe Caufes are faid to be Extrinfic, which introduce fome- thing into a Subject from without; as when Fire introduces Heat, &c.

Sometimes it denotes a Thing added, or applied to ano- ther. — Thus, Accidents and Adherences are laid to be Ex- trinfic to the Subject; and thus Virion is Extrinfic to the Wall feen. See Accident.

EXUBERANCE, in Rhetoric, 8S& a Redundancy, See Redundant.

an the Interlines, are Marks of Poifon. See Poison.

EXUSTION, a burning with Fire; as it is ufed in fome Operations by Surgeons. Sec Burning.

EXU VIjE, in Nat. Hiitory, the Shells, and other marine Bodies, which are found every where in the Bowels of the Earth. See Earth, Fossil, Deluge, Shell, &c.

Sclerot:

outer Coat, as already obferved, going to form the otica, the inner to the Choroid?! = and the naAJU

t0 the Retina. See Optic Nerve, &c. f Beiide which, the Motorii,  ^ th? continual Motion of the Si"

fcJSSj* S OT fi Pp" 7 D g " & nai fy; imdei mt ° HP™ *<: Cornea, to moiften it, and facilitate its Motion'

& S'd t^£>T^L PaaS '\° t f° the ^' e F ° P,:rIy S 6 Tbars Mi "S down the Cornea, are ftopp'd by the

Tt7^' ,k Appendages thereof. Edge of the under Eye-lid, along which they ru2 till

whYreb V. pi -f i C 'f S '?T* the. 0rfor ' °i S" Ity ,hcy Ul info two fmafl Ho '« in ' te g«« Angle, one n

X" J f >6 Placed; the &5S e «««««, orJ&e-^w, each ^-/^, fedl'd ~ f' W I ^ f f t"T \ Carunck . « Eminence, which ferves to feparate and keep

"„j ■...!!SriSS ', A°° fierc? Ippreffi<«>? f the Light, them open, and which was anciently taken for the GlaJ,

dula Lacryraalis. See Lacrymalis Glandala, VuizSa

and keep off Flies and Moats : And the Canthi, or Angle. See each Part particularly defcribed under its proper Article, Palpeera, Supercilium, Cilia, Orbit, and Canthus.

The Eye, properly fo call'd, is of a globular Form, and confifts of Tunicks, Humours, and VeJJels. See Tunic, Humour, $$c.

In fome Parts it is lined with Tilt; and it is moved with

Lacrymalia, Tears, Oc.

3°. The Eye receives Arteries, both from the internal and external Carotids, and returns the Blood by Veins that go to the Jugulars. See Carotid and Jugular.

The Mufcles of the Eye are fix; four of which are from their Situarion call'd ReSi, or flraight Mufclcs; and two, Obliijui. The ReSi come from fevcral Points of the

-,, r, ,. 1 ^, , *,. V ...... iwu, y_tui,i/ftu. a ne j\cLu come rrom leverai joints 01 the

Mufiks ■ which two latter are by fome Anatomifts, tho' Bottom of the Orbir, and run immediately between the Sole- iomewhat inaccurately, rpdnn'Hsmrmn rVm n ah,«..B.... .._■, ' m , ,. ~ } . _"'- v " Ll ^ f'.'-c

fomewhat inaccurately, reckon'd among the confiituent Parti of the Eye.

The Ttmicks, Coats, 01- Membranes of the Eye are fix


 * 1) *viz. i°. The Adnata, or Conjunctiva, covering the wholi

Ball of the Eye, except the fore-parr, call'd the Sight; and

rotica and Adnata : They derive feveral Denominations from their feveral Offices, viz. AtteUens, or fuperbtis, which draws the .Eye upwards': •Deprimens, or hwniliu which calls it down : Adducens, and Votator, which draws the Eye towards the Nofe : And Abducens

jnaking what we popularly call the White of the Eye : Indicator, which draws it the other Way towards' the"

Xho this is not reckon d as a proper Tunic ot the Eye. leflir Angle. The two oblique Mufcles are, the fit

a". Immediately under the Adnata, is the Sclerotica, perior, call'd alfo Rotator, and Trochlearis ■ and the

which covers the whole Globe of the Eye; being opake inferior. See each Mufcle in its proper Place, At-ol,

every where but in the fore-part, which covers the Sight lens, Deprimens, Abducens, Abducens, Orliqu us ,

and is traniparent like Horn; which has occafion d Ana- Trochlearis, SS>&

tomifts to account this a diftincf Membrane, the 3 d The whole Structure and Apparatus of the Eve tends

jn Number, and to denominate it the Cornea. The 4 th to this, that there be produced a diflinft and vivid Col-

is. the Choroides fituate immediately Under the Sclerotica, ledion in the Bottom of the Eye, directly under the Pupil.

Its fore-part, like the former^ is tranfparent and there- f all the Rays, which proceeding from any Point of "an

fee accounted a diftincl, or t th Coat, and_call'd the Uvea. Object, and entering the -.Eye, penetrate the cryftalline

middle is an Aperture, or Perforation, call'd the 'Pupil, or Apple of the Eye, about which the Iris forms Ring. From the Ihfide of this Tunic, fpring certain

In order to this, the Rays from any radiant or re- flecting Point, ftriking on the Cornea, are refracted towards the Perpendicula

-1, and thus determined to proceed thro*

Fibres, which fpreading round [the cryflalhne Humour, form the Aperture of the Pupil to the Surface of rbe Cry-

tbe ZigamentumOliare. The 6th Tunic, which fome fla lli ne. While other Ra r ys w hich enter'd fo obliquely as.

only make the U, is the Retina fo call'd, as refembhng t0 ^ thmn fhe ^ ^ rcfe(rted out ^ that

a Net and covering only the Fund, or Bottom of the Eye, ,h e y may not difturb the Diflinflnefs of the Sight; and

oppohte to the Sight. others whofe lefs Obliquity threw them between the

Of the three proper Tunicks the Sclervtica, Choroides, Uvea and vitrious Humour / arc e xtingui(h'd in the Dark-

ZiaAT^/ 6 ^ 1 ^""^ fr ° m the ®° W M *' er < n^ 'hereof: So that none can be propagated thro' the

ceing detach d from the Brain as an outer Coat, or Cover vitrious, bat fuch as paffing thro' the Pupil, firike on the

of the Optic Nerve, till arriving at the Ball of; the Eye Cryftalline. See Crystalline and Refraction.

H *Z l**?"^ IM0 ^' Tu "J! T ^,ff oi, .f " denv f d In the mean Time the Iris, contracting by its circute, or

Irpm the Pta Mater, and tranlmitted likewile from the d;i ating by its right Fibr( . S( thc 'Pupilla of the Eye; admits

I Hi*' fewe?