MOD 13 Part 2 - Ear

ruptured tympanic membrane

Another disorder that can be caused either by trauma or disease, is what it sounds like—a tear, or perforation, of the eardrum

otorrhea

any external ear condition, a discharge (-rrhea) from the ear

pure tone audiometry

measurement of perception of pure tones—is made with all extraneous noises screened out

speech audiometry

measurement of the ability to hear and understand speech

process of hearing

the series of events involved in the process of hearing (audi/o, acous/o). Sound waves, conducted by air, enter the ear with the aid of the auricle. They are conducted along the auditory meatus to the tympanic membrane. When the taut eardrum is struck by the sound waves, it begins to vibrate, moving the three small bones in the middle ear. The ossicles amplify the sound waves and conduct them through the middle ear, to the oval window, and into the inner ear. Sound is then picked up by the sensory hair cells of the cochlea, which produce impulses that are transmitted by the auditory nerve fibers to the auditory cortex. Viewing the accompanying animation may help you to better synthesize this process

otitis media (OM)

the structure of the eustachian tube and its connection to the nasopharynx causes the middle ear to be prone to infection or inflammation. Caused by a myriad of bacteria, acute otitis media is characterized by a sense of fullness in the ear, diminished hearing, pain, and fever. If the inflammation is accompanied by a pus-filled fluid, it is called suppurative OM. If it is characterized, instead, by a clear fluid discharge, it is secretory OM

mastoidectomy

the surgical removal of the mastoid process

Rinne tuning fork test

the tuning fork is placed alternately near the auditory canal and behind the ear on the mastoid bone to compare how the patient hears sounds transmitted through air (near the auditory canal) with how the patient hears sounds transmitted through bone. This test helps the examiner distinguish between conductive and sensorineural hearing loss. Not being able to hear the tuning fork longer when the sound waves are conducted through the air is a sign of conductive hearing loss. The Weber test is done in conjunction with the Rinne test

otosclerosis

(ot/o = ear + -sclerosis (abnormal condition of hardening), which involves the excess formation of bony tissue in the labyrinth that attaches to and prevents movement of the stapes. The stapes can no longer transmit sound vibrations to the inner ear and there is conductive hearing loss

cholesteatoma

Hearing loss may also be affected by a cystic mass composed of epithelial cells and cholesterol (chol/e = bile; steat/o = fat; -oma = tumor). This can not only occlude the middle ear but also destroy adjacent bones

inner ear structures

Once sound is conducted to the oval window, it moves into the inner ear, or labyrinth. There is more than one labyrinth. The inner ear itself is composed of a bony labyrinth, inside of which is a membranous labyrinth surrounded by a fluid called perilymph (peri = surrounding; lymph/o = lymph) and filled with endolymph (endo- = within). The bony labyrinth consists of three parts: the vestibule (vestibul/o), semicircular canals, and the cochlea (cochle/o). The first two contribute to the body's sense of equilibrium, or balance. The cochlea houses the organ of Corti, a sensitive receptor with hair cells that relay sound waves to the eighth cranial nerve, or vestibulocochlear nerve. This nerve then conveys impulses to the temporal lobe of the brain. Before long, we'll see that Sara's hearing difficulty may very well be caused by age-related changes of these inner ear structures.

otalgia

Outer ear conditions can be accompanied by pain (-algia) in the ear

tympanoplasty

Surgical repair of the bones of the middle ear (tympan/o = eardrum + -plasty = surgical repair)

structures of the ear

The ear (ot/o, aur/o, auricul/o) has the dual function of hearing (audi/o, acous/o) sound and serving as the organ of balance, or equilibrium. The ear is divided into three anatomic regions: the outer ear, the middle ear, and the inner ear (labyrinth/o). The inner ear is also called the labyrinth. It is the organ of receptors for both hearing and balance.

external ear structures

The external ear consists of the auricle or pinna, which gathers sound waves and funnels them into the external auditory canal, or meatus. The auricle, a skin-covered cartilaginous flap, projects from the side of the head. The temporal (tempor/o) bone and its small projection point called the mastoid process (mastoid/o) are both immediately behind the external auditory meatus. The auditory canal, the external portion of which is about one inch in length, is lined with glands that secrete a sticky substance called earwax, or cerumen (cerumin/o). Cerumen lubricates the ear and prevents the entry of foreign particles into the internal portions of the ear. The tympanic membrane, or eardrum (tympan/o, myring/o), marks the division between the external and middle ear. This thick membrane in the middle ear transmits sound vibrations from the external auditory canal through the middle ear and on to the inner ear.

audiogram

The listener signals when the tone is perceived and the results are plotted on a graph

equilibrium

The structures of the ear involved in maintaining equilibrium are the macula (macul/o) and the semicircular canals, both of which are found in the vestibule. Sensitive hair cells and fluid within these structures can detect changes in the position of the head. Movement of the hair cells generates nerve impulses, which communicate through the brain to the body's muscles and provide for the recovery of balance

Meniere disease

The structures responsible for equilibrium and balance are housed in the labyrinth of the inner ear. This affects the vestibular labyrinth and can lead to profound hearing loss. The cause of the disease is unknown, but it is marked by vertigo, a sensation that the body is spinning or that objects are spinning around the body

otoscopy

This is the process of viewing (-scopy) the structures of the outer and middle ear with a handheld, lighted magnifying device called an otoscope. A pneumatic attachment to the otoscope allows evaluation of the eardrum's mobility

middle ear structures

Within the middle ear cavity are three small bones called the ossicles (ossicul/o), or ossicular chain. These ossicles include the malleus, incus, and stapes (staped/o), named because they resemble a hammer, anvil, and stirrup, respectively. They are attached to, or articulate with, one another. The "handle" of the malleus is connected to the tympanic membrane. When the eardrum conducts sound to these three ossicles, the ossicles transmit the sound to the oval window through vibration of the stapes. The footplate of the stapes, when it moves, touches this oval window, which leads to the inner ear. Within the middle ear is the opening for the auditory, or eustachian tube (salping/o). This structure is sometimes identified as the pharyngotympanic tube as well because it joins the nasopharynx (part of the throat) with the middle ear cavity, where the tympanic membrane is. The eustachian tube is lined with a mucous membrane and its job is to equalize air pressure between the middle ear and the external atmosphere.

impacted cerumen

a blockage of the external auditory canal with earwax, or cerumen

microtia

a condition of abnormally small (micro-) auricles

presbycusis

a loss of hearing common in the elderly (presby-)

otologist

a physician who studies and treats diseases of the ear

tinnitus

a subjective noise such as ringing, buzzing, whistling, or clicking—heard in the absence of sound—is another symptom of Meniere disease. Various options exist to treat this disorder, including tranquilizers, antihistamines, diuretics, and surgery to reduce the pressure of the endolymph on cochlear hair cells. It can also spontaneously go away, as Sara's did after two years

paracusis

abnormality (para-) of hearing

acoutic neuroma

also called a vestibular schwannoma, is a benign tumor of the auditory nerve that can cause tinnitus and hearing loss. A benign tumor that develops from the acoustic nerve and grows in the auditory canal. The presence of the tumor may cause tinnitus, vertigo, or progressive hearing loss. The tumor is removed either by surgical incision or by radiosurgery, the use of x-ray beams to destroy the growth

audiometer

an electric device used to measure the sensitivity of hearing by delivering a series of acoustic tones that range from very low to very high frequencies

macrotia

auricles, or pinnae, were abnormally large (macro- = large; ot/o = ear; -ia = condition)

conductive hearing loss

characterized by hearing loss resulting from damage to or malformation of the middle or outer ear

ceruminoma

derived from the glands that produce earwax, which can obstruct the ear canal and detract from a patient's ability to hear

hearing aids

electronic devices that amplify sound—may be worn externally or implanted within the ear

audiometric testing

evaluates hearing acuity and helps to establish the degree and severity of hearing loss (audi/o = hearing; -metric = pertaining to measurement)

sensorineural hearing loss

from damage to the cochlea or auditory nerve

infectious myringitis

inflammation occurs in the eardrum (myring/o) and vesicles due to a bacterial or viral infection

labyrinthitis

inflammation of the inner ear (labyrinth/o), may be due to either infection or trauma. Symptoms usually include vertigo, nausea, and nystagmus

mastoiditis

inflammation of the mastoid process (mastoid/o) of the temporal bone

otitis externa

is inflammation of the outer ear

tympanotomy

or myringotomy, shown here, is a surgical incision (-tomy) of the tympanum to relieve the pressure and build-up of fluid. This procedure may be required for those who don't respond to antibiotic treatment.

tympanometer

process of measuring (-metry) the condition and mobility function of the tympanic membrane or eardrum (tympan/o). A tympanogram is the graph seen as a result of this test

otoplasty

refers to the surgical or plastic repair (-plasty) and/or reconstruction of the external ear

stapedectomy

removal (-ectomy) of the third ossicle, the stapes (staped/o)

cochlear implant

surgically implanted to electrically stimulate the cochlea

Weber tuning fork test

the tuning fork is placed on the midline of the skull to assess bone conduction of sound for evaluation of auditory acuity. It can detect unilateral conductive hearing loss and unilateral sensorineural hearing loss. With normal hearing, the sound the patient hears is the same loudness on each side

universal newborn hearing screening (UNHS)

uses otoacoustic emissions (OAEs) measured by insertion of a probe into the infant's ear canal. Four electrodes are then placed on the baby's head and auditory brainstem response (ABR) is measured while the baby sleeps

anacusis

which is the general term for hearing (-cusis) loss or deafness. (The spelling of this term actually comes directly from the Greek: an- (without [privative case]) + akousis hearing)

tympanostomy

which is the surgical creation of an opening (-stomy) through the eardrum to promote drainage. This procedure also allows the insertion of artificial tubes to maintain this new opening, something often useful in preventing those recurrent ear infections mentioned earlier. In the accompanying photograph, we see the tympanostomy tube in place