Areas of the Ear Outer Ear (Hearing) Pinna(Auricle) External Auditory Canal/Meatus Ceruminous glands Tympanic Membrane(Eardrum)
Areas of the Ear Middle Ear (Hearing) Auditory Ossicles Malleus/Hammer Incus/Anvil Stapes/Stirrup Tiny Muscles Tensor tympani Stapedius Eustachian tube
Areas of the Ear Inner Ear Hearing and Equilibrium Oval Window Round WIndow Bony Labyrinth with perilymph • Membranous Labyrinth with endolymph
Bony Labyrinth Vestibule • Equilibrium Receptors • Utricle and Saccule Semicircular Canals • Equilibrium Receptors • Ampulla Cochlea • Hearing receptors • Modiolus • Scala Vestibuli, Scala Tympani, Scala Media • Organ of Corti with Hair cells
Physiology of Hearing The auricle directs sound waves into the external auditory canal When sound waves strike the eardrum, the pressure of air cause the eardrum to vibrate Vibration of the eardrum cause the malleus, incus and stapes to vibrate. As the stapes move back and forth, it pushes the membrane of the oval window in and out.
The movement of the oval window sets up flid pressure waves in the perilymph of the cochlea. As the oval window bulges inward, it pushes the perilymph of the scala vestibuli. Pressure waves are transmitted from the scala vestibuli to the scala tympani and eventually to the round window, causing it to bulge outward in the middle ear.
As the pressure waves deform the walls of the scala vestibuli and scala tympani, they also push the vestibular membrane back and forth creating pressure waves in the endolymph inside the scala media. The pressure waves in the endolymph cause the basilar membrane to vibrate, which moves the hair cells of the spiral organ against the tectorial membrane. Bending of the stereocilia produces receptor potentials that ultimately lead to the generation of nerve impulses.
Deafness Conductive Hearing Loss Occurs when sound cannot reach the cochlea Causes Obstruction (Cerumen Impaction) Mass loading ( Middle ear effusion) • Ear canal is very sensitive • Removal with a loop or hook Stiffness effect (Otosclerosis) Discontinuity (Ossicular disruption) • Resorption of bone • Stapedectomy
Symptoms Tinnitus - clicking in the ears Feeling of fullness in the ear Sounds are faint or non existent Needing everything to be repeated Withdrawal from social activities Depression and embarrassment
Treatment Removal of the offending obstruction Surgery Hearing Aids Draining of fluids that have built up Softening and removal of excessive ear wax Antibiotics such as oral medication or ear drops
Sensorineural Hearing Loss Disturbance in the inner ear in the cochlea or the acoustic nerve to the brain Causes Long-term exposure to loud sounds Ototoxic medications Trauma Aging
Symptoms: Unable to hear high tones (high frequency hearing loss) Can not understand or hear speech Loud TV volume Always needing conversation repeated Retreat from social activities and interaction with others Depression
Treatment Remove ear wax or use of antibiotics to treat an ear infection Intratympanic steroids may be effective Hearing aids Surgery: Tympanoplasty for repair of a perforated eardrum Myringotomy tubes surgically inserted to drain the ear of fluids caused by infections. Cochlear implant
Presbycusis Causes Atrophy of the sensory cells Loss of neuron in the cochlea and CNS Atrophy of the wall of cochlea Mechanical change of the outer ear
Meniere’s Disease Disorderof the middle ear with an increase amount of endolymph that enlarges the membranous labyrinth Treatment Symptomatic relief
Symptoms Hearing loss of several hours or more Vertigo, severe nausea, vomiting sweating Tinnitus Feelings of fullness or pressure in the ear Headache Abdominal pain Diarrhea
Otitis Media Infectionof the middle ear caused mainly by bacteria and associated with infections of the nose and throat. Causes Allergies Persistent infections Ear trauma Swelling of the adenoids
Treatment Oral or ear drop antibiotics Adenoidectomy Surgical repair of ruptured eardrum Otitis media complications may include: Cyst of the middle ear (cholesteatoma) Facial paralysis Mastoiditis Epidural abscess (inflammation surrounding the brain) Partial or profound hearing loss
Mixed Hearing Loss Combination of conductive and sensorineural losses Chronic ear infection that is a fairly common diagnosis could result in a defect ear drum and/or middle ear ossicle damages. Surgery is often attempted but not always successful. Functional Hearing Loss Individual does not respond to voice and appears not to hear
Treatments Hearing Aid an electroacoustic device which typically fits in or behind the wearers ear, and is designed to amplify and modulate sound for the wearer. receives sound, amplifies it, and transmits this stronger sound down the ear canal into the ear. sound is amplified to make the weak and distorted signals more audible.
The microphone - picksup the sound and sends itto the amplifier.The amplifier - makesthe sound louder.The receiver - sends theamplified sound into theear canal.The battery - suppliesthe power to the hearingaid.
Cochlear Implants Surgically implanted electronic device Provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. Referred to as bionic ear
can restore hearing in patients suffering deafness due to loss of sensory hair cells in their cochlea electrical hearing is much less rich than natural hearing, and offers only very limited appreciation of musical melody, or speech understanding in noisy environments.
Sound no longer travels via the ear canal and middle ear It will be picked up by a microphone and sent through the devices speech processor to the implants electrodes inside the cochlea.