Chapter 9: The Sensory system

Sclera

outer protective layer of the eye

Cornea

transparent anterior part of the sclera

Choroid

middle layer of the eye with many blood vessel

Iris

muscular structure that gives the eye its color

Pupil

opening in the center of the iris

Lens

lies directly behind the pupil and functions to focus and bend light

Retina

innermost layer of the eye which contains the vision receptor

Aqueous fluid

watery liquid found in the anterior cavity of the eye

Vitreous Fluid

Jelly liquid found behind the lens in the posterior cavity of the eye

Meibomian glands

oil glands found in the upper and lower edges of the eyelids

Lacrimal glands and ducts

produced and drain tears

Optic nerve

carries visual impulses from the retina to the brain

Conjunctiva

mucous membrane lining the eyelids and covering the anterior portion of the sclera

Orbit

where the eyes located, the bony protective cavity if the skull

Inner eye three layers

cornea, sclera, uvea

Uvea consist of:

choroids, ciliary body, and the iris

Ciliary body

consist of the ciliary muscles and the ciliary process.

Optic disc or blind spot

one small area of the retina has no cones or rods and doesn’t produce visual image.

Outer eye

consist of the orbital cavity, the ocular muscle, the eyelids, conjunctival membrane, and lacrimal apparatus.

Choroiditis

inflammation of the choroid

Cilietomy

surgical removal of a portion of the ciliary body

Corodiastasis

dilation of the pupil

Corneal

pertaining to the cornea

Cycloplegia

paralysis of the ciliary body

Iritis

Inflammation of the iris

Iridomalacia

softening of the iris

Keratitis

inflammation of the cornea

Ocular

pertaining to the eyes

Ophthalmology

study of the eyes

Optometry

measurement of the eyes and vision

Papilledema

swelling of the optic disk

Aphakia

absence if the lens

Pupillary

pertaining to the pupil

Retinopathy

any diseases of retina

Scleritis

inflammation of the sclera

Uveitis

inflammation of the uvea

Vitreous

glass-like substance

Blepharospasm

twitching of the eyelids

Conjunctivitis

inflammation of the conjunctiva

Dacryoma

swelling of a blocked tear duct

Amblyopia

dulled vision

photosensitivity

sensitivity to light

Scotoma

area of darkness in the visual field

Heteropsia

unequal vision in the two eyes

Achromatopsia

color blindness

Amblyopia

reduced or dulled vision

Ametropia

general term for any error of refraction in which light is not properly focused on the retina

Anisocoria

inequality in the size of the pupils

Astigmatism

refractive disorder in which excessive curvature of the cornea or lens causes light to be scattered over the retina rather than focused on the single point.

Blepharoptosis

drooping of the upper eyelids; often called ptosis for short

Cataract

condition in which the crystalline lens becomes cloudy or opaque as a result of protein deposits on its surface.

Dacryocysivitis

inflammation or swelling of a lacrimal duct, usually as a result of a blockage

Diabetic retinopathy

damage to the retina resulting from vascular abnormalities in the eyes of patients with diabetes

Diplopia

double vision

Glaucoma

causing damage to the retina and/or optic nerve and irreversible loss of vision

Hemianopia

blindness in one half of the visual field

Hyperopia

Farsightedness; refractive disorder in which light is focused on a point from of the retina.

Myopia

nearsightedness; refractive disorder in which light is focused on a point in front of the retina

Nyctalopia

night blindness

Nystagmus

constant rhythmic oscillation (movement back and front) of the eyeball

Presbyopia

reduced ability of the eye to focus on nearby object due to age-related reduction in the elasticity of the crystalline lens

Retinal detachment

hereditary disease involving progression degeneration of the rods and cones of the retina

Scleritis

inflammation of the sclera; usually occurs in conjunction with rheumatoid arthritis and other collagen diseases.

Scotoma

an area of darkness in an otherwise normal filled of vision

Strabismus

any disorder in which both eyes cannot focus on the same point. (lazy eyes)

Stye

inflammation of a gland within the eyelid

Uveitis

inflammation of the iris

Xeropthalmia

dryness of the conjunctiva, often as a result of vitamin deficiency.

Fundoscopy

use of a funduscope to examine the innermost structures of the eye, particularly the blood vessels supplying the retina and the optic disk.

Gonioscopy

measurement of the angle of the anterior chamber of the eye

Ophthalmoscopy

visual examination of the interior of the eye using an ophthalscope

Retinoscopy

technique in which a beam of light is shone on the retina to determine if errors of refraction occur.

Snellen’s chart

standard test of visual acuity in which a subject is asked to read letter and number on a chart 20 feet away. (“E” chart)

Tonometry

measurement of pressure within the eye used to detect glaucoma

Cataract surgery

procedure in which an opaque or clouded lens is removed and artificial lens is inserted in its place.

Iridectomy

surgical removal of a portion of the iris

Keratoplasty

procedure in which an opaque section of the cornea is replaced with normal tissue

Orthopic training

exercise program designed to restore normal coordination of the eye muscles in patients with strabismus

radial keratotomy

procedure in which a series of shallow, pokelike incision are made to flatten the cornea, correcting an error of refraction commonly associated with nearsightedness.

Auricle

soundwaves are encouraged toward the ear canal

Tragus

the hard little flap of cartilage that stick out in front of the ear canal, and the earlobe

Cerumen (earwax)

the external auditory meatus is lined with numerous glands that secrete a yellowish waxy substance

Ossicle

conduct the sound waves through the middle ear

Bones in the order of their vibration:

malleus, incus, and the stapes

Oval window

as the stapes moves, it touches a membrane. It separates the middle ear from the inner ear

Auditory or Eustachian tube

a canal leading from the middle ear to the pharynx

Inner ear

also called “labyrinth” because of its circular, mazelike stracture.

Bony

the part of the labyrinth that leads from the oval window

Cochlea

snail-shaped, contains auditory liquids that the vibration travel through

Organ of Corti

the cochlea is a sensitive auditory receptor

Tympanic membrane

comes from the Greek tympanon, meaning “drum”, because it resembles a drum (hence eardrum)

Stapes

latin for “stirrup”, was named, not surprisingly, for its stirruplike shape

3 organs within the inner ear

semicircular canals, the saccule, and utricle

Endolymph

organs contain a fluid, as well as sensitive hair cells.

Vestibulocochlear Nerve

impulses generated by the hair cells in the inner ear and vestibular apparatus are conveyed to the brain. (Eighth cranial nerve/ auditory nerve)

Anacusis

complete hearing loss

Conductive hearing loss

hearing loss due to an impairment in the transmission of sound because of damage to the eardrum or ossicle or obstruction of the ear canal

Labyrinthitis

inflammation of the inner ear, usually due to viral infection

Mastoiditis

inflammation of the air cells of the mastoid process

Meniere’s Disease

rare disorder characterized by progressive deafness, vertigo, and tinnitus, possibly due to swelling of membranous structures within labyrinth.