SHH 382: Exam 3

Central Auditory System

auditory pathways

Peripheral Auditory System Physiology

captures sound signals, transmits and transforms them into information that can be experienced as an auditory percept

Peripheral Auditory System Anatomy

outer ear, inner ear, middle ear

Central Auditory System Anatomy

cochlear nerve, brainstem, thalamus, auditory cortex

Central Auditory System Physiology

interprets auditory information delivered by the peripheral auditory system

Outer Ear

pinna, ear cannal, ear drum, acoustic energy

Middle Ear

ear drum, ossicles, muscles, mechanical energy

Inner Ear

vestibular system, cochlea, auditory nerve, hydraulic and electrical energy

Ear drum

vibrates under sound pressure (acoustic energy —> electrical energy) and sets the ossicles into motion

Ossicle to oval window

ossicle movement sets inner ear fluid into motion (mechanical energy —> hydraulic energy)

Cochlear hair cells

bend under fluid movement (hydraulic energy —> electrical energy) and send nerve impulses along the auditory nerve

Conductive Mechanism Anatomy

outer ear, middle ear

Conductive Mechanism Physiology

natural transmission (movement) of sound through the outer ear, ear drum and middle ear

Sensorineural Mechanism Anatomy

cochlea, auditory nerve

Sensorineural Mechanism Physiology

transmission of energy through the cochlea (sensory organ) and the auditory nerve (neural structure)

Pinna

helps with sound localization, visible part of ear, channels sound waves into the ear canal

Ear canal protective function

cartilaginous part lined with hair follicles and glands that secrete cerumen

Ear canal resonator

open at the pinna and closed at the ear drum, the resonant frequency of the ear canal is 3000-3500 Hz

Middle ear physiology

increases the amplitude of sound waves to overcome the impedance mismatch between the middle ear (air) and inner ear (fluid); transfer of mechanical energy

Malleus (hammer)

first middle ear bone attached to the tympanic membrane

Incus (anvil)

connected to the malleus and the stapes

Stapes (stirrup)

connected to the incus on one end, and embedded into the oval window of inner ear on other end

Impedance

resistance to movement; a measure of the difficulty of signal transmission through a medium (ex; air, liquid)

Impedance Mismatch

air-filled middle ear offers low impedance to sound waves; fluid-filled inner ear offers high impedance to sound waves

Pressure amplification

decrease in area (oval window vs. tympanic membrane) results in increased pressure

Eustachian tube

connection between the middle ear and the nasopharynx; middle ear end ope, nasopharyngeal end open during yawning and swallowing

Eustachian tube ventilation

equalize air pressure between the otherwise closed middle ear

Middle ear infection

no mucus drainage due to blockage of pharyngeal opening

Vestibular system

organ of balance, monitors the motion and position of the head in space

Cochlea

organ of hearing, filled w fluid, built of bone

Basilar membrane

base of cochlear duct

Tonotopic arrangement

high frequency sounds processed at the base, low-frequency sounds processed at the apex

Organ of Corti

sensory organ of hearing, which transforms fluid vibrations into electrical energy