Anatomy - Globe

Question 1

External fibrous tunic

Answer 1

Contains the cornea and sclera

Question 2

Middle vascular tunic

Answer 2

Contains the urea
Iris, ciliary body, choroid

Question 3

Internal nervous tunic

Answer 3

Contains retina (3 parts)

Question 4

Chambers of the eye

Answer 4

Anterior chamber - anterior to iris, aqueous humor
Posterior chamber - between iris and ciliary body/zonules, aqueous humor
Vitreous chamber - vitreous body - larges acellular, a vascular, gelatinous
Lens

Question 5

Tunics surrounding globe

Answer 5

Fibrous - completely surrounds globe
Vascular and nervous - incomplete

Question 6

Sclera

Answer 6

Forms 75-80% of the posterior globe
Comprised of dense feltwrok collagenous & elastic fibers
Toughness resists pressure of inner aqueous or gelatinous bodies & gives shape to globe

Question 7

Features of sclera

Answer 7

Opaque
Relatively few vessels
Fibers of optic nerve exits area cribrosa near caudal pole

Question 8

Cornea

Answer 8

Forms anterior 20-25% of globe
Projects (bulges) anteriorly from sclera
Normally clear and colorless

Question 9

Features of cornea

Answer 9

Distinctly demarcated from sclera at the corneoscleral junction or limbus
Locating inflammation - if vessels move when you touch them, located to conjunctiva if dont move its in sclera

Question 10

Uveitis

Answer 10

Inflammation of the uvea or middle tunic
Common in Appaloosa horses

Question 11

Cilliary body & processes

Answer 11

Body - near limbus,
Processes - bears a 360 series of elevations of processes
Zonular fibers - suspensory ligaments of lens, extend from cilliary processes to the lense & suspending it and provide function

Question 12

Iris

Answer 12

Variably color extension of choroid
Suspended from edge of ciliary body and sclera
Pupil is the central opening, diameter can change
Pupil differently shaped among domestic animals

Question 13

Corpora Nigra or iridic granules

Answer 13

Found in ungulates. Extensions of Iris found in horses

Question 14

Horizontal pupils

Answer 14

Allow for better vision /field of view of the ground/surrounding areas
Can help eliminate dazzling light or refraction

Question 15

Iris - smooth muscles

Answer 15

Innervated by CN and control pupil size
Dilator - radial fibers throughout iridial substance
- mydriasis (dilation)
Sphincter - circumferential fibers surrounding pupillary margin
- under PNS control
- myosis (constriction)

Question 16

dilator

Answer 16

Dilator - radial fibers throughout iridial substance
- mydriasis (dilation)

Question 17

Sphincter

Answer 17

Sphincter - circumferential fibers surrounding pupillary margin
- under PNS control
- myosis (constriction)

Question 18

Cats & pupils

Answer 18

Small cats have vertical pupils when constricted, round when dilated
Big cats have round pupils

Question 19

Parts of vascular tunic

Answer 19

Choroid - lines posterior & circumferential parts of globe
Black pigmented inside

Question 20

Tapetum lucidum

Answer 20

Unpigmented part of of choroid in all domestic mammals except pigs
- lies dorsal to fundus
- reflects photons bc of absence of pigment
- gives eye shine at night among species

Question 21

fundus

Answer 21

Internal portion of globe visible via scope

Question 22

Ora serrata

Answer 22

Ridge or edge at the junction of visual and non-visual retina caused by the sudden thinning of tissue as rods and cones are lost. Also demarcates choroid from ciliary body

Question 23

Lens

Answer 23

Flexible, layered structure that changes shape to focus light onto retina
Generally is asymmetrically biconvex anterior curvature is less than posterior
Constantly under tension, zonular fibers attach here
Action fo ciliary muscle & body alter lens shape by altering tension on capsule

Question 24

Chamber behind lens

Answer 24

Vitreous chamber

Question 25

Anterior and posterior chamber

Answer 25

Aqueous humor produced by ciliary epithelium (pars ciliaris retinae) moves from posterior chamber to anterior chamber & is returned to venous circulation via spaces of Fontana at iridocorneal angle

Question 26

Cause for glaucoma

Answer 26

Blocked iridocorneal angel and spaces of fontana

Question 27

Nervous tunic

Answer 27

Pars optica retinae
Pars ceca retinae (posterior epi on iris and ciliary body)
Direct outgrowth of developing brain

Question 28

innervation of eye

Answer 28

CNII - visual afferent
CNIII - pregang PNS fibers - ciliary ganglion in orbit
CNV - ophthalmic branch GSA fibers

Question 29

Innervation of Extraocular structures

Answer 29

CNIII - orbital fissure
CNIV - orbital fissure
CNV - trigeminal
ophthalmic branch via orbital fissure - afferent from eyelids & conjunctiva (medial)
Maxillary branch via round foramen - afferent from eyelids & conjuctiva (Lat/vent)