22- Special Senses - Hearing and Balance

Hearing

The interpretation of vibrations that allows us to perceive sound.

Sound

interpretation of vibrations.

Volume

Measured by wave amplitude.

Pitch

Measured by wave frequency.

Incus

One of the auditory ossicles in the middle ear.

Auricle

The outer part of the ear, also known as the pinna.

Tympanic membrane

Commonly known as the eardrum; it vibrates in response to sound waves.

Cochlea

A spiral-shaped inner ear structure that plays a key role in hearing.

Vestibulocochlear nerve

Cranial nerve VIII; responsible for hearing and balance.

Auditory ossicles

The three small bones in the middle ear (malleus, incus, stapes) that transmit sound vibrations.

Stapes

The stirrup-shaped bone in the middle ear.

Hair cells

Sensory cells in the inner ear that convert mechanical sound vibrations into neural signals.

Stereocilia

Tiny hair-like structures on hair cells that detect sound vibrations.

Tip link

A structure that connects adjacent stereocilia in hair bundles.

Basilar membrane

Membrane that runs along the cochlea and supports the organ of Corti.

Endolymph

The fluid contained within the membranous labyrinth of the inner ear.

Perilymph

The fluid located between the bony labyrinth and the membranous labyrinth.

Scala vestibuli

The upper duct of the cochlea filled with perilymph.

Scala tympani

The lower duct of the cochlea filled with perilymph.

Cochlear duct

The middle duct of the cochlea filled with endolymph.

Spiral organ (organ of Corti)

The sensory organ of hearing located in the cochlea.

Otoliths

Calcium carbonate crystals that contribute to balance.

Macula

Sensory organ for static equilibrium found in the utricle and saccule.

Cupula

A gelatinous structure in the semicircular canals that aids in balance.

Crista ampullaris

Sensory structure within the semicircular canals that detects rotational movement.

Static equilibrium

The maintenance of the body's position relative to gravity.

Dynamic equilibrium

The maintenance of the body's position during movement.

Semicircular canals

Structures in the inner ear responsible for detecting rotational acceleration.

Auditory pathway

The neural route that sound signals follow from the cochlea to the auditory cortex.

Cochlear nuclei

The brainstem nuclei that receive input from the cochlear nerve.

Inferior colliculus

A midbrain structure that acts as a relay station for auditory information.

Medial geniculate nucleus

The thalamic relay nucleus for auditory signals.

Primary auditory cortex

The part of the brain responsible for processing auditory information.

Malleus

The hammer-shaped bone in the middle ear.

Oval window

An opening in the cochlea that receives vibrations from the stapes.

Round window

An opening in the cochlea that allows for pressure release.

Tectorial membrane

A membrane in the cochlea that interacts with stereocilia.

Basilar membrane displacement

Movement of the basilar membrane caused by sound wave vibrations.

Action potentials

Electrical signals generated by hair cells in response to sound.

Supporting cells

Cells that provide structure and support to hair cells in the organ of Corti.

Auditory tube

A canal that connects the middle ear to the nasopharynx.

Temporal lobe

The brain region where the primary auditory cortex is located.

Kinocilium

A single long hair-like structure found on hair cells.

Cerebellum

Part of the brain involved in coordination and balance.

Motor nuclei

Nuclei that control eye muscles in response to balance signals.

Vestibular area of the cortex

Brain region where vestibular information is processed.

Vestibular nuclei

Brainstem nuclei that receive input from the vestibular nerve.

Helicotrema

The apex of the cochlea where the scala vestibuli and scala tympani meet.

Ossicular chain

The three small bones in the middle ear that transmit sound.

Cochlear branch

Part of the vestibulocochlear nerve responsible for hearing.