Inner Ear Anatomy and Basilar Membrane Function - VOCABULARY Flashcards

Vocabulary-style flashcards covering key concepts from the lecture notes on inner ear anatomy, the cochlea, and basilar membrane function.

Inner ear

The fluid-filled, bony labyrinth in the temporal bone that contains the vestibular (balance) and cochlear (hearing) components; the vestibulocochlear nerve carries auditory information to the brain.

Bony labyrinth

The rigid, bony outer shell of the inner ear within the temporal bone that houses the fluid-filled chambers.

Vestibular system

The balance portion of the inner ear that detects head position and movement, interacting with visual and somatosensory systems.

Cochlea

The snail-shaped, fluid-filled structure of the inner ear where the organ of Corti resides and hearing occurs.

Organ of Corti

The sensory organ for hearing located on the basilar membrane, containing hair cells.

Hair cells

Sensory receptors for hearing in the organ of Corti; include inner hair cells (IHCs) and outer hair cells (OHCs).

Stereocilia

Hair-like bundles on hair cells that bend in response to fluid motion, triggering receptor potentials.

Inner hair cells (IHCs)

One row of hair cells with U-shaped stereocilia; primary transducers sending signals to the auditory nerve via the spiral ganglion.

Outer hair cells (OHCs)

Three rows of hair cells with V- or W-shaped stereocilia; amplify basilar membrane motion.

Basilar membrane

The flexible membrane along the floor of the scala media that vibrates in response to sound, with base stiff and apex floppy.

Scala vestibuli

The upper cochlear chamber filled with perilymph.

Scala tympani

The lower cochlear chamber filled with perilymph.

Scala media (cochlear duct)

The middle chamber filled with endolymph; contains the Organ of Corti.

Endolymph

Fluid in the scala media with high potassium content, creating a unique electrochemical environment.

Perilymph

Fluid in the scala vestibuli and scala tympani that surrounds the endolymph within the cochlea.

Oval window

The membrane connecting the middle ear to the cochlea via the stapes; movement initiates cochlear fluid motion.

Round window

A pressure-relief valve that accommodates fluid movements within the cochlea.

Stapes

The small ossicle whose footplate pushes on the oval window to transmit vibrations into the cochlea.

Modiolus

The central bony core of the cochlea that houses the auditory nerve fibers.

Spiral lamina

A bony shelf on the modiolus that supports the Organ of Corti.

Helicotrema

Apex region where the scala vestibuli and scala tympani connect and share fluid.

Spiral ganglion

Cluster of neuron cell bodies in the modiolus that form the auditory nerve fibers.

Auditory nerve

Nerve fibers carrying auditory information from the spiral ganglion to the brainstem and cortex.

Organ of Corti and basilar membrane relationship

The Organ of Corti sits on the basilar membrane; hair cells and tectorial membrane interact to transduce sound.

Basilar membrane traveling wave

A frequency-dependent wave along the basilar membrane that peaks at different locations for different frequencies.

Tonotopic organization

Spatial mapping of different frequencies along the basilar membrane and auditory pathways.

Tectorial membrane

Membrane above the hair cells that interacts with stereocilia to influence transduction.

Hasler membrane

A term referenced in class notes as located at the bottom of the organ of Corti in some slides.

IHC stereocilia pattern

Inner hair cells have a single row with stereocilia arranged in a U shape.

OHC stereocilia pattern

Outer hair cells have three rows with stereocilia arranged in a V- or W-shape.

Hair cell transduction

Movement of hair bundles opens ion channels, generating receptor potentials that signal to the spiral ganglion and beyond.

Traveling wave consequence

Each frequency component stimulates a specific place along the basilar membrane, enabling tonotopic coding.

500 Hz example

A 500 Hz pure tone causes the stapes/oval window to move in and out at 500 cycles per second.

Base vs apex frequency mapping

High frequencies peak near the base of the cochlea; low frequencies peak near the apex.

Three primary inner ear structures

Semicircular canals, vestibule, and cochlea.

Unrolled cochlea analogy

A teaching visualization that flattens the cochlea to study frequency mapping along its length.