The Human Ear Name the structures that make

The Human Ear

• Name the structures that make up the outer ear. – Pinna – External Auditory Meatus (Ear Canal) – Tympanic Membrane (Ear Drum)

• What are the ossicles? – The small bones of the ear. – Hammer (Malleus) – Anvil (Incus) – Stirrup (Stapes)

• Name the structures that make up the bony (osseous) labyrinth. – Cochlea – Semicircular Canals – Vestibule

• Which structures are not involved in hearing? They contain the receptors for the sense of ↔. – Semicircular Canals – Vestibule

• Which structure allows pressure in the middle ear to be equalized with Patm? • Auditory Tube (Eustacian Tube)

• This structure vibrates as longitudinal sound waves strike it; then transmits the vibrations to the ossicles. – Tympanic Membrane (Ear Drum)

• Connects the nasopharynx and middle ear – Auditory (Eustacian) Tube

• The structure that transmits vibrations from the stirrup to the fluid in the inner ear. – Oval Window

• The fluid that bathes the sensory receptors of the inner ear. – Endolymph

• The fluid contained within the osseous labyrinth that bathes the membranous labyrinth – Perilymph

• Contains the Organ of Corti – Cochlea

• Identify the major areas of the membranous labyrinth: semicircular canals, saccule, utricle, and cochlear duct

• ID each receptor: Organ of Corti, Crista Ampullaris, Macula

Organ of Corti

Acoustic Macula Otoliths Gelatinous Cap Hair Cells Supporting Cells Vestibular Nerve Axons

Normal Hair Cells

Damaged Hair Cells

• The receptors for ____ ↔ are found in the crista ampullaris of the ____. • These receptors respond to Δs in ____ motion. • When motion begins, the ___ fluid lags behind and the ___ is bent, which excites the hair cells. • When motion stops suddenly, the fluid flows in the opposite dxn and again stimulates the hair cells

• The receptors for ___ ↔ are found in the maculae of the ___ and ___. • These receptors report the position of the head in space. • Tiny stones found in a gel overlying the hair cells roll in response to the pull of ___.

• As they roll, the gel moves and tugs on the hair cells, exciting them. • Besides the ↔ receptors of the inner ear, the sense of ___ and ___ are also important in helping to maintain ↔.

Deafness

Conduction • Can result from the fusion of the ossicles

Sensorineural • Can result from damage to the cochlear nerve

Sensorineural • Sound is heard in one ear but not in the other, during both bone and air conduction

Conduction • Often improved by a hearing aid

Conduction and Sensorineural • Can result from otitis media – an inflammation/infection of the middle ear (the cavity between the eardrum and the inner ear).

Conduction • Can result from XSive earwax or a perforated eardrum

Sensorineural • Can result from a blood clot in the auditory cortex of the brain

Conduction Deafness • hearing loss due to problems with the bones of the middle ear

Sensorineural (Central) Deafness • Hearing loss or impairment due to a lesion or defect of the cochlea or the acoustic nerve.