Comprehensive Eye and Ear Anatomy, Functions, and Disorders

Auditory

Pertaining to sense of hearing

Acoustic

Pertaining to sound or hearing

Cerumen

Earwax secreted by ceruminous glands lining auditory canal

Tympanic Membrane

Eardrum located between outer and middle ear

Mastoid process

Temporal bone containing hollow air space surrounding the middle ear

Auditory Ossicles

Transmit sound waves from eardrum to inner ear by vibration

Eustachian Tubes

Lead from middle ear to nasal cavity and throat

Inner Ear

Contains sensory receptors for hearing and balance

Oval window

Membrane separating the middle ear from the inner ear

Cochlea

Snail-shaped structure where sound vibrations are converted into nerve impulses

Organ of Corti

Relays vibrations to auditory nerve fibers

Semicircular canals

Contain endolymph and sensitive hair cells that assist with equilibrium

Acoustic nerves

Transmit information to the brain

Air Conduction

Process of sound waves entering the ear through pinna

Bone Conduction

Occurs as eardrum vibrates causing auditory ossicles to vibrate

Sensorineural Conduction

Occurs when sound vibrations reach inner ear

Audiologist

Specializes in measurement of hearing function and rehabilitation of hearing impairments

Speech-language pathologist

Assists patients with problems related to swallowing, speech, and communication disorders

Otalgia

Pain in the ear

Otorrhea

Any discharge from the ear

Otitis Media

Inflammation of middle ear

Vertigo

Sense of dizziness and loss of balance

Tinnitus

Ringing, buzzing, or roaring sound in one or both ears

Hearing Loss

Complete or partial loss of ability to hear

Presbycusis

Gradual loss of sensorineural hearing related to aging

Conductive hearing loss

Sound waves are prevented from passing air to fluid-filled inner ear

Sensorineural hearing loss

Due to damage to auditory nerve or hair cells in inner ear

Audiometry

Use of audiometer to measure hearing acuity

Otoscope

Instrument used to examine external ear canal

Tympanometry

Use of air pressure in ear canal for testing disorders of middle ear

Weber and Rinne tests

Use of tuning fork to distinguish between conductive and sensorineural hearing losses

Tympanostomy Tubes

Ventilating tubes inserted into the eardrum for drainage and pressure relief

Cochlear implant

Bypasses damaged portion of ear and directly stimulates auditory nerves

Hearing aids

Electronic devices worn to correct hearing loss

Analog hearing aid

Uses microphone to detect/amplify sounds

Digital hearing aid

Computer chip converts incoming sound into code that is filtered before being amplified

Adnexa of the Eyes

The structures outside the eyeball, including the orbit, eye muscles, eyelids, eyelashes, conjunctiva, and lacrimal apparatus.

Bony Orbit

Cavity of skull that contains and protects the eyeball and associated muscles, blood vessels, and nerves; also known as the eye socket.

Muscles of Eye

Six major eye muscles (three pairs): superior and inferior oblique muscles, superior and inferior rectus muscles, lateral and medial rectus muscles.

Binocular vision

Coordination of eye muscles allowing for depth perception.

Depth perception

Ability to see things in three dimensions.

Eyelids, Eyebrows, and Eyelashes

Provide protection from foreign matter, excessive light, and injuries.

Cilia

Small hair making up eyebrows/eyelashes.

Conjunctiva

Transparent mucous membrane lining underside of the eyelid protecting the exposed surface of the eyeball.

Lacrimal Apparatus

Structures producing, storing, and removing tears.

Lacrimal glands

Located on underside of upper eyelid just above outer corner of each eye.

Lacrimal fluid

Maintains moisture on the anterior surface of eyeball.

Lacrimal canal

Ducts at the inner corner of each eye that collect tears emptying them into lacrimal sacs.

Lacrimal sac

Enlargement of the upper portion of the lacrimal duct.

Lacrimal duct

Passageway draining excess tears into nose.

Ocular

Pertaining to the eye.

Extraocular

Outside the eyeball.

Intraocular

Within the eyeball.

Sclera

White of the eye that maintains shape and protects delicate inner layers of tissue.

Choroid

Opaque middle layer of eyeball that provides blood supply to the entire eye.

Retina

Innermost layer lining posterior segment of the eye that receives nerve impulses and transmits them to the brain via optic nerve.

Anterior Segment of Eyeball

Front one-third of eyeball located behind the cornea and in front of the iris.

Aqueous humor

Helps maintain shape and nourishes intraocular structures.

Intraocular pressure

Measures fluid pressure inside the eye which is regulated by the rate at which aqueous humor enters/leaves the eye.

Posterior Segment of Eyeball

Remaining two-thirds of the eyeball located behind the iris and in front of the ligaments holding the lens in place.

Ciliary Body

Set of muscles and suspensory ligaments that adjust thickness of the lens and refine the focus of light rays on retina.

Iris

Colorful circular structure surrounding the pupil that controls the amount of light entering through the pupil.

Cornea

Transparent outer surface of eye covering iris and pupil that focuses light rays entering the eye.

Pupil

Black circular opening in the center of the iris permitting light to enter the eye.

Lens

Clear, flexible, curved structure contained within clear capsule located behind the iris and pupil that focuses images on the retina.

Accommodation

The process whereby the eyes make adjustments for seeing objects at various distances.

Convergence

Simultaneous inward movement of the eyes toward each other to maintain single binocular vision as an object comes nearer.

Emmetropia

Normal relationship between the refractive power of the eye and the shape of the eye that enables light rays to focus correctly on the retina.

Refraction

Ability of the lens to bend light rays so they focus on the retina.

Visual Acuity

Ability to distinguish object details and shape at a distance.

Ophthalmologist

Specializes in diagnosing/treating diseases/disorders of eyes.

Optometrist

Provides diagnosis of eye diseases, measuring accuracy of vision determining need for corrective lenses.

Optician

Health care practitioner who designs, fits, and dispenses lenses for vision correction.

Conjunctivitis

Inflammation of conjunctiva usually due to infection or allergy; also known as Pinkeye.

Xerophthalmia

Dry eye due to decreased production of tears by tear glands.

Corneal abrasion

Injury to outer layers of cornea.

Diabetic retinopathy

Damage to retina as complication of uncontrolled diabetes.

Cataract

Loss of transparency of lens causing progressive loss of visual clarity.

Floaters

Particles of cellular debris in vitreous humor casting shadows on the retina.

Miosis

Contraction of pupil in response to light.

Mydriasis

Dilation of pupil.

Nystagmus

Involuntary, constant, rhythmic movement of eyeball.

Retinal detachment

Separation of some or all of the retina from the choroid.

Glaucoma

Group of diseases characterized by increased intraocular pressure resulting in damage to the retinal nerve fibers and optic nerve.

Macular Degeneration

Progressive condition causing damage to the macula, resulting in the loss of central vision.

Photophobia

Excessive sensitivity to light.

Strabismus

Improper eye alignment due to the inability of eye muscles to coordinate.

Presbyopia

Decline of near vision related to aging.

Astigmatism

Lack of focus due to uneven curvature of cornea.

Hyperopia

Farsightedness; light rays focus beyond the retina.

Myopia

Nearsightedness; light rays focus in front of the retina.

Blindness

Inability to see; legal blindness = best-corrected vision of 20/200.

Snellen chart

Measures visual acuity, recorded as fraction with 20/20 representing normal vision.

Slit-lamp ophthalmoscopy

Focusing the beam of light onto parts of the eye to permit examination of structures at front of the eye.

Tonometry

Measurement of intraocular pressure; abnormally high pressure may indicate glaucoma.

Corneal transplant

Surgical replacement of scarred/diseased cornea with clear corneal tissue from donor.

L A S I K

Treats vision conditions caused by the shape of cornea.

Retinopexy

Reattaches retinal detachment.