Anatomy and Physiology of the Ear

Vocabulary flashcards covering the key terms, anatomical structures, and physiological processes of the outer, middle, and inner ear based on the lecture notes.

Pinna

The structure of the outer ear that directs sound into the ear canal.

Ear Canal

An auditory canal that is 1 to 1.5 inches long with a resonant frequency around $3\,\text{kHz}$, which is the frequency range where people hear best.

Eardrum

A membrane that vibrates as acoustic waves strike it, capable of detecting vibrations as small as $\frac{1}{10}$ the diameter of a hydrogen atom.

Ossicles

A group of three small bones in the middle ear—the Hammer (Malleus), Anvil (Incus), and Stirrup (Stapes)—that function as a mechanical amplifier carrying vibrations from the eardrum across the middle ear.

Hammer (Malleus)

One of the three middle ear ossicles that attaches to the eardrum to transmit acoustic vibrations.

Anvil (Incus)

The middle ossicle bone that connects the hammer (malleus) to the stirrup (stapes).

Stirrup (Stapes)

The innermost ossicle bone whose movement against the oval window initiates a hydraulic wave in the fluid of the inner ear.

Cochlea

A snail-shaped, fluid-filled structure of the inner ear where fluid waves pass along the basilar membrane.

Basilar Membrane

A membrane inside the cochlea lined with cilia (hairs) over nerve bundles that responds to sound frequencies ranging from high frequencies ($1,500\text{--}20,000\,\text{Hz}$) at its base to low frequencies ($200\text{--}600\,\text{Hz}$) at its apex.

Organ of Corti

A structure containing nerve endings beneath cilia that transmits both amplitude and frequency information to the auditory nerve.

Auditory Nerve

The nerve that receives sound amplitude and frequency information from the Organ of Corti and transmits it to the brain.

Eustachian Tube

A tube connecting the air-filled middle ear chamber to the back of the mouth, responsible for equalizing air pressure between the middle ear and the external environment.

Acoustic Reflex

An involuntary muscle contraction tightening the muscles connected to the eardrum and ossicles in response to loud sounds, reducing vibration amplitude across the middle ear.

Temporary Threshold Shift (TTS)

A temporary reduction in hearing sensitivity caused by muscle contraction during the acoustic reflex in response to loud sound exposure.

Tinnitus

The perception of noise or ringing in the ears when no external sound source is present.