Special senses of sight and hearing

Special senses

Chemical receptors and physical receptors

Chemical receptors

Smell, taste, touch

Physical receptors

Sight (electromagnetic energy) and hearing (mechanical energy)

Orbit

Bony cavity (socket) of the eye

Extraocular muscles

Muscles within orbit but outside eyeball that move the eyes

Eyebrows

Crescent-shaped line of hairs on superior edge of the orbit

Eyelids

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

Eyelashes

Stiff hairs projecting from eyelid margins

Conjunctiva

Mucous membrane that lines anterior surface of eyeball and underside of eyelid

Lacrimal glands

Secrete tears to cleanse and moisten eyeball surface

Lacrimal sac

Stores tears

Lacrimal ducts

Channels that carry tears to the eyes

Nasolacrimal ducts

Carry tears from lacrimal glands to the nose

Sclera

White of eye; helps maintain shape of eyeball and extends from cornea to optic nerve

Cornea

Transparent portion; provides most of optical power of the eye

Choroid

Opaque layer; contains vessels that supply blood to the eye

Ciliary body

Thickened portion between choroid and iris

Lens

Transparent structure posterior to pupil that bends and focuses light rays on retina

Iris

Pigmented muscular ring that surrounds and controls size of the pupil

Pupil

Opening in middle of iris through which light enters the eye

Retina

Contains visual receptors (rods and cones)

Optic nerve

Carries nerve impulses from retina to the brain to give us sense of sight

Chambers

Interior spaces that contain fluid

Aqueous humor

Fluid in anterior chamber of the eye

Vitreous humor

Fluid in posterior chamber of the eye

Photoreceptors

Specialized visual receptor cells in retina

Rods

Black and white receptors in dim light

Cones

Color receptors

Fovea centralis

Point in center of retina

Optic disc

Where nerve fibers from retina converge to form optic nerve

Refraction

Bending of light rays

Accommodation

Automatic adjustment of focusing the eye

Refractive errors

Vision problems caused by improper focusing of light

Hyperopia

Farsightedness

Myopia

Nearsightedness

Presbyopia

Farsightedness caused by aging

Astigmatism

Irregularity of curve of cornea or lens that distorts light entering the eye

Conjunctivitis

Pinkeye; inflammation of conjunctiva

Keratitis

Inflammation of cornea related to corneal scratch or damage

Dacryocystitis

Inflamed lacrimal sac

Blepharoptosis

Drooping of eyelid

Ectropion

Turning outward of eyelid

Entropion

Turning inward of eyelid

Hordeolum

Sty; infection of oil gland of eyelash

Xerophthalmia

Dry eyes

Glaucoma

Increased intraocular pressure

Cataract

Cloudiness or opacity of lens

Ophthalmoscope

Instrument used to examine interior of eye by looking through the pupil

LASIK

Laser-assisted in situ keratomileusis; procedure to correct vision problems

Scleral buckle

Permanent silicone band attached to scleral peripheral behind the eye to pull retina together

Ophthalmology

Study of the eye

Ophthalmologist

Provides eye care from examining eyes and prescribing corrective lenses to performing surgery

Optometrist

Doctor of optometry (O.D.) who examines eyes and prescribes corrective lenses

Optician

Technician who fills eyeglass prescriptions and dispenses eyewear

External ear

One of the three sections of the ear

Middle ear

One of the three sections of the ear

Internal ear

One of the three sections of the ear

Auricle

Outer ear

External acoustic meatus

Passageway of external ear

Tympanic membrane

Eardrum

Ceruminous glands

Glands that secrete cerumen (earwax)

Tympanic cavity

Contains auditory ossicles in middle ear

Auditory ossicles

Bones of middle ear

Auditory tube

Tube associated with middle ear

Vestibule

Bony labyrinth of semicircular canals and cochlea

Malleus

Hammer-shaped auditory ossicle

Incus

Anvil-shaped auditory ossicle

Stapes

Stirrup-shaped auditory ossicle

Function of ossicles

Transmit sound vibrations to internal ear

Labyrinth

Inner ear structure containing sensory receptors for hearing and balance

Cochlea

Changes sound waves to nerve impulses that brain can process

Impacted cerumen

Buildup of earwax

Otalgia

Ear pain

Otodynia

Ear pain

Conductive hearing loss

Hearing loss caused by interference with sound conduction

Sensorineural hearing loss

Nerve-related hearing loss

Presbycusis

Hearing loss associated with aging

Anacusis

Total deafness

Otitis

Inflammation of the ear

Otitis externa

Inflammation of outer ear

Otitis media (OM)

Inflammation of middle ear

Otitis interna

Inflammation of inner ear

Myringitis

Inflammation of tympanic membrane

Mastoiditis

Inflammation of mastoid process

Labyrinthitis

Inflammation of labyrinth

Otosclerosis

Hardening of ear structures affecting hearing

Ménière’s syndrome

Inner ear disorder causing vertigo and hearing symptoms

Vertigo

Sensation of spinning or dizziness

Tinnitus

Ringing or buzzing in the ears

Otoplasty

Surgical repair of auricle of the ear

Mastoidectomy

Surgical removal of mastoid process of temporal bone

Myringectomy

Surgical removal of all or part of tympanic membrane

Tympanectomy

Surgical removal of all or part of tympanic membrane

Myringotomy

Surgical incision of eardrum to create opening for placement of drainage tubes

Tympanoplasty

Surgical correction of damaged tympanic membrane

Stapedectomy

Surgical removal of the stapes

Labyrinthotomy

Surgical incision into labyrinth

Audiology

Specialty dealing with hearing and hearing disorders

Audiologist

Specialist who measures hearing and treats hearing impairments

Otoscope

Instrument with light and lenses used to visually examine external ear and eardrum