Vet 300 Chapter 14

Ocular system

Responsible for vision

Eyes

The receptor origins for sight

opt/i, opt/o, optic/o, ocul/o, ophthalm/o

Combining forms for Eye or sight

Extraocular

Outside the eyeball

Intraocular

within the eyeball

Periocular

around the eyeball

Adnexa

Accessory structures of an organ

Stroma

Term used to describe the supporting tissue of an organ

Orbit

Bony cavity of the skull that contains the eyeball

Periorbita

eye socket

Eye muscles

seven major muscles attached to each eye that make a range of movement possible

Binocular

Both eyes

Extrinsic muscles

six muscles that attach the outside of the eyeball to the bones of the orbit

Extrins/o

Combining form for Contained outside

Levator palpebrae muscles

muscles that raise the upper eyelid

Eyelids

each eye has an upper and lower one to protect the eye from injury, foreign material, and excessive light

Blephar/o

Combining form for Eyelid

Palpebra or palpebrae (plural)

another term for eyelid

Palpebral

pertaining to the eyelid

Canthus

The angle where the upper and lower eyelids meet

Canth/o

Combining form for corner of the eye

Tarsal plate

platelike framework within the upper and lower eyelids that provides stiffness and shape

Tars/o

Combining form for edge of the eyelid or "ankle" joint

Meibomian glands or tarsal glands

sebaceous glands on the margins of each eyelid

Eyelashes

the edge of each eyelid has hairlike structures called cilia; protect eyes from foreign material

Conjunctiva

mucous membrane that lines the underside of each eyelid

Conjunctiv/o

Combining form for Conjunctiva

Nictitating membrane, third eyelid, nictitans, or haws

conjunctival fold attached at the medial canthus that moves across the cornea when the eyelids close

lacrimal apparatus

the structures that produce, store, and remove tears

Lacrimation

condition of normal tear secretion

Lacrim/o, Dacry/o

Combining forms for teardrop, tear duct, or lacrimal duct

Lacrimal canaliculi

the ducts at the medial canthus that collect tears and drain them into the lacrimal sac.

Lacrimal sac or dacryocyst

the enlargement that collects tears at the upper portion of the tear duct

Nasolacrimal duct

passageway that drains tears into the nose

Dorsal punctum

the small spot near the upper medial canthus where the nasolacrimal duct begins

Ventral punctum

The small spot near the lower medial canthus where the nasolacrimal duct begins

Punctum

a point or small spot

Eyeball or globe or orb

A sphere with multilayered walls

Sclera (white of the eye)

The fibrous outer layer of the eye that maintains the shape of the eye

Scler/o

Combining form for Sclera or hard

Episclera

thin membrane covering the sclera

Cornea

The anterior portion of the sclera is transparent

Corne/o, Kerat/o

Combining forms for Cornea

Descemet's membrane

the innermost or deepest layer of the cornea

Choroid

the opaque middle layer of the eyeball that contains many blood vessels and provides the blood supply for the entire eye

Opaque

That light cannot pass through

Tapetum lucidum (Choroid tapetum)

the brightly colored iridescent reflecting tissue layer of the choroid of most species

Tapetum nigrum

the black pigmented tissue layer of the choroid in some species

Choroid/o

Combining form for Choroid

Iris

The pigmented muscular diaphragm of the choroid that surrounds the pupil

Corpora nigra

the black pigmentation at the edge of the iris in equine and ruminants

Ir/i, ir/o, irid/o, irit/o

Combining forms for Iris of eye

Pupil

The circular opening in the center of the Iris

Pupill/o, Core/o

Combining forms for Pupil

Constriction

Making an opening smaller

Miosis

pupillary constriction

Dialation

Making an opening larger

Mydriasis

Pupillary dilation

Lens

the clear, flexible, avascular, curved capsule located posterior to (behind) the Iris and pupil

Phac/o

Combining form for lens of the eye

Ciliary body

The thickened extension of the choroid that assists in accommodation or adjustment of the lens

Ciliary muscles

located in the ciliary body, are muscles that adjust the shape and thickness of the lens

Iridocorneal

pertaining to the iris and cornea

uvea

term used to describe the iris, ciliary body, and choroid

Limbus

term used for the corneoscleral junction

Retina

The nervous tissue layer of the eye that receives images and lines the posterior chamber of the eye

Retin/o

Combining form for Retina

Rods

Specialized cells of the retina that react to light

Cones

Specialized cells of the retina that react to color and fine detail

Optic disk (Blind Spot)

The region of the eye were nerve endings of the retina gather to form the optic nerve; doesn't contain any rods or cones

Macula lutea

A centrally depressed, clearly defined yellow area in the center of the retina

Fovea centralis

Contains the greatest concentration of cones in the retina (no rods) and the area of sharpest vision

Macul/o

Combining form for Spot

Lute/o

Combining form for Yellow

Fove/o

Combining form for Pit

Fundus

The part of the retina opposite the lens that includes the retina, optic disc, macula lutea, and fovea centralis

Anterior segment

The cranial 1/3 of the eyeball and is divided into anterior and posterior chambers

Anterior chamber

The eye cavity located between the caudal surface of the cornea and the cranial surface of the Iris

Posterior chamber

The eye cavity located between the caudal surface of the iris and the cranial surface of the lens

Aqueous humor

Watery fluid that fills the anterior and posterior chambers of the eye

Aque/o

Combining form for Water

Vitreous chamber

The caudal two-thirds chamber of the eyeball

Vitreous humor

the soft, clear, jellylike mass that fills the vitreous chamber

Vitre/o

Combining form for Glassy

Accommodation

the process of eye adjustments for seeing objects at various distances

Refraction or focusing

The process of the lens bending the light rays to help them focus on the retina

Convergence

Simultaneous inward movement of both eyes

Acuity

Sharpness or acuteness, usually in reference to vision

Conjunctival scrape

diagnostic test using an instrument to peel cells from the conjunctiva so that they can be viewed microscopically

Electroretinography

procedure of recording the electrical activity of the retina

Electroretinogram (ERG)

The record of electrical activity of the retina

Fluorescein Dye Stain

diagnostic test to detect corneal injury by placing dye on the surface of the cornea

Goniometry

procedure to measure the drainage angle of the eye

Gon/i

Combining form for angle or seed

Menace response

diagnostic test to detect vision in which movement is made toward the animal to test whether it will see movement and try to close its eyelids

Ophthalmoscope

instrument used for ophthalmoscopy

Ophthalmoscopy (funduscopy)

procedure used to examine the interior eye structures; may be direct or indirect

Palpebral reflex

diagnostic test in which the eye should blink in response to touch to the medial canthus of the eye

Pupillary light reflex (PLR)

response of pupil to a bright light source

Schirmer Tear Test

diagnostic test using a graded paper strip to measure tear production