Glossary

 

 

Auditory canal

A channel leading from the external ear (pinna) to the eardrum or tympanic membrane.

 

Basilar membrane

A membrane located between the scala tympani and the scala media in the cochlea.

 

Cochlea

A spiral bony structure located in the inner ear that contains the hair cells which transduce sound.

 

Conductance

The relative ability of an electrical charge to move from one point to another, measured in siemens (S) and represented by the symbol g.

 

Endolymph

The fluid in the scala media of the cochlea, containing high potassium ion and low sodium ion concentrations.

 

Eustachian tube

An air-filled tube connecting the nasal cavities and the middle ear.

 

Hair cell

An auditory cell that transduces sound energy into a change in membrane potential, or a vestibular cell that converts head movements into a change in membrane potential.

 

Helicotrema

A small hole at the apex of the cochlea that connects the scala tympani to the scala vestibule.

 

Incus

An ossicle in the middle ear attached to malleus and stapes; shaped somewhat like an anvil.

 

Inner ear

The cochlea, which is part of the auditory system, as well as the labyrinth, which is part of the vestibular system.

 

Inner hair cell

A type of auditory cell in the organs of Corti; the primary transducer of sound into change in membrane potential.

 

Malleus

An ossicle in the middle ear connected to the tympanic membrane; shape somewhat resembles a hammer.

 

Middle ear

The tympanic membrane and the ossicles

 

Neurotransmitter

A chemical released from a presynaptic element upon stimulation and activates postsynaptic receptors.

 

Organ of Corti

An auditory receptor organ which contains rods of Corti, hair cells, and supporting cells.

 

Ossicle

One of the three tiny bones in the middle ear

 

Outer ear

The pinna and the auditory canal

 

Outer hair cell

A type of auditory receptor cell in the organ of Corti within the inner ear.

 

Oval window

A small hole in the bony cochlea, where movement of the ossicles is transmitted to the movement of the cochlea fluids.

 

Perilymph

The fluid in the scala vestibule and scala tympani within the cochlea, containing low potassium ion and high sodium ion concentrations.

 

Pinna

The funnel-shapped external ear made largely of cartilage covered by skin.

 

Receptor potential

A change induced by a stimulus in the membrane potential of a sensory receptor.

 

Reissner’s membrane

A membrane in the cochlea that separates the scala vestibule and the scala media.

 

Round window

A hole covered by membrane in the bony cochlea that is continuous with the scala tympani.

 

Scala media

A chamber in the cochlea between the scala vestibule and the scala tympani.

 

Scala tympani

A chamber in the cochlea which spans from the helicotrema to the round window.

 

Scala vestibule

A chamber in the cochlea which spans rom the oval window to the helicotrema.

 

Stapes

An ossicle in the middle ear connected to the oval window; shaped somewhat like a stirrup.

 

Stereocilium

A hair-like cilium attached to the top of a hair cell in the organ of Corti.

 

Tectorial membrane

A membrane that hangs over the organ of Corti in the cochlea.

 

Tympanic membrane

A membrane at the end of the auditory canal that vibrates in response to changes in air pressre; also known as eardrum.