Medical Terminology Chapter 8

blephar/o

eyelid

conjunctiv/o

conjunctive

corne/o

horny

dacry/o

tears, lacrimal sac or lacrimal duct

dipl/o

two, double

irid/o

iris

kerat/o

hard, cornea

lacrim/o

tear, lacrimal apparatus

ocul/o, ophthalm/o

eye

-opia

vision

opt/o

light, eye, vision

phac/o

lens

presby/o

old age

pupil/o

pupil

retin/o

retina

scler/o

relating to the sclera, hard

uve/o

denoting the pigmented middle eye layer

orbit

bone cavity (socket) formed by seven bones of the skull

extraocular muscles

those muscles within the orbit but outside the eyeball that move the eyes

eyebrows

are the crescent-shaped line of hairs on the superior edge of the orbit

eyelids

the moveable upper and lower folds that cover the surface of the eyeballs when they close

eyelashes

stiff hairs projecting from the eyelid margins

lateral angle of eye

the angle formed by the junction of the lateral parts of the upper and lower eyelids

conjunctiva

the mucous membrane that lines the anterior surface of the eyeball and the underside of the eyelid

lacrimal glands

secrete tears to cleanse and moisten the eyeball surface

lacrimal sac

stores tears

lacrimal ducts

channels that carry tears to the eyes

nasolacrimal ducts

carry tears from the lacrimal glands to the nose

3 layers of the eyeball (outermost to innermost)

1. fibrous layer

2. vascular layer

3. inner layer

sclera and cornea

fibrous layer of eyeball

sclera

white of the eye, helps maintain the shape of the eyeball and extends from the cornea to the optic nerve

cornea

the transparent portion that provides most of the optical power of the eye through its ability to bend light rays to focus on the surface of the retina

choroid, ciliary body, and iris (pupil)

vascular layer

ciliary body

a thickened portion between the choroid and iris

choroid

the opaque layer of the eyeball that contains vessels that supply blood to the eye

iris

the pigmented muscular ring that surrounds and controls the size of the pupil

pupil

the opening in the middle of the iris through which light enters the eye

retina and optic nerve

inner layer

retina

the innermost layer of the eye that contains visual receptors (rods and cones)

optic nerve

the first cranial nerve, carries nerve impulses from the retina to the brain to give us sense of sight

—> exits the eyeball through the optic foramen (opening) in the orbit

anterior chamber

the space between the cornea and the lens filled with a watery fluid called aqueous humor

posterior chamber

the large open space between the lens and retina that contains a semi-gelatinous liquid called the vitreous humor

photoreceptors

the specialized visual receptor cells in the retina

two types of photoreceptors

rods and cones

rods

black and white receptors that respond to dim light

cones

color receptors that provide color vision and sharp vision (visual activity)

macula

oval area of the retina

fovea centralis

the center pit of a macula

—> saturated with cones and thus permits the best possible color vision

optic disc

the location where nerve fibers from the retina converge to form the optic nerve

—> referred to as the blind spot because it has no photoreceptors

refraction

the bending of light rays, is the ability of the eye to change the direction of light in order to focus it on the retina

accommodation

the automatic adjustment of focusing the eye by flattening or thickening the lens

hyperopia

the medical term for farsightedness, a condition in which the image falls behind the retina

myopia

the medical term for nearsightedness, a condition in which the image falls in front of the retina

presbyopia

farsightedness caused by aging

astigmatism

means the light coming into the eye does not focus on a single point, this condition is caused by an irregularity of the curve of the cornea or lens that distorts light entering the eye

conjunctivitis

commonly known as pinkeye, an inflammation of the conjunctiva

keratitis

an inflammation of the cornea that occurs when the cornea has been scratched or otherwise damaged

dacryocystitis

an inflamed lacrimal sac

blepharoptosis

drooping of the upper eyelid

ectropion

a condition in which the eyelid is turned outward away from the eyeball

hordeolum

also called a sty, an infection of the oil gland of an eyelash

xerophthalmia

dry eyes, occurs when the surface of the eye becomes dry, often from wearing contact lenses or from a diminished flow of tears

glaucoma

a disease characterized by an increase in intraocular pressure (IOP) that causes damage to the optic nerve

cataract

cloudiness or opacity of the lens

ophthalmoscope

the instrument by which practitioners can examine the interior of the eye by looking through the pupil

laser-assisted in situ keratomileusis (LASIK)

this procedure uses a laser to create a corneal flap and reshape the cornea

scleral buckle

a permanent silicone band that attaches to the scleral peripheral behind the eye, pulling the retina together

ophthalmologist

provides eye care ranging from examining eyes to prescribing corrective lenses to perform surgery

ophthalmology

medical specialty concerned with the eye

optometry

the profession concerned with examination of the eyes and related structures

optometrist

a doctor of optometry (O.D.)

opticians

the technicians who fill eyeglass prescriptions and dispense eyewear

ear

the organ of hearing and equilibrium (balance)

three sections of the ear

1. external

2. middle

3. internal

external ear

consists of the auricle (outer ear), external acoustic meatus (passageway), and tympanic membrane (eardrum)

cerumen

earwax

—> protects the ear by preventing dust, insects, and some bacteria from entering the middle ear

middle ear

consists of the tympanic cavity with its auditory ossicles (bones), associated muscles, and the auditory tube

internal ear

contains the vestibule, which includes the bony labyrinth of semicircular canals and the cochlea

tympanic membrane

sound waves entering the ear vibrate the tympanic membrane

the three auditory ossicles

1. malleus

2. incus

3. stapes

auditory tube

reaches from the tympanic cavity to the nasopharynx to help equalize pressure in the ear with outside atmospheric pressure

internal ear

contains a bony labyrinth

labyrinth

maze that contains the sensory receptors for hearing and balance

—> major structures include semicircular canals (organ of balance) and cochlea (organ of hearing)

acous/o, acus/o, acoust/o

hearing

audi/o

sound

aur/o, auricul/o, ot/o

ear

myring/o

tympanic membrane (eardrum)

staped/o

stapes (smallest ear bone)

tympan/o

eardrum

impacted cerumen

an accumulation of earwax in the external acoustic meatus, may cause hearing loss

earache

termed otalgia or otodynia, may be caused by trauma or infection

otitis

any inflammation of the ear but can be divided into the otitis externa (inflammation of the outer ear), otitis media (OM) (inflammation of the middle ear), and otitis interna (inflammation of the inner ear), with otitis media being the most common type

deaf

unable to hear

conductive hearing loss

occurs when sound waves are not conducted through the external ear to the ossicles of the middle ear

sensorineural hearing loss

occurs when there is damage to the cochlea of the internal ear or to the nerve pathways to the brain

presbycusis

a progressive hearing loss that occurs with aging

anacusis

total deafness

myringitis

inflammation of the tympanic membrane

mastoiditis

inflammation of the mastoid air cells, which are intercommunicating cavities in the mastoid process of the temporal bone

labyrinthitis

an inflammation of the labyrinth, sound being unable to travel from the outer ear to the internal ear