Crash course : Hearing and Balance

Outer Ear

The visible part of the ear (pinna) and auditory canal; collects and funnels sound.

Middle Ear

Chamber containing ossicles that amplify and transmit sound vibrations.

Inner Ear

Contains cochlea (hearing) and vestibular system (balance); filled with fluid.

Inner Ear

Contains cochlea (hearing) and vestibular system (balance); filled with fluid.

Tympanic Membrane

The eardrum; vibrates in response to sound waves.

Ossicles

The three tiny bones of the middle ear: malleus, incus, stapes.

Oval Window

Membrane-covered opening that transmits vibrations from stapes to cochlear fluid.

Cochlea

Spiral-shaped, fluid-filled organ in inner ear where sound transduction occurs.

Organ of Corti

The hearing organ in the cochlea containing hair cells.

Hair Cells

Mechanoreceptors in inner ear that convert mechanical vibrations into neural signals.

Basilar Membrane

Membrane in cochlea that vibrates at different locations for different frequencies.

Tectorial Membrane

Gel-like shelf in cochlea that hair cells brush against during sound vibration.

Vestibular System

System in inner ear responsible for balance and spatial orientation.

Semicircular Canals

Three fluid-filled loops that detect rotational head movements.

Vestibule

Central chamber of bony labyrinth containing utricle and saccule.

Utricle and Saccule

Sacs in vestibule that detect linear acceleration and gravity.

Otoliths

Tiny crystals in utricle and saccule that add weight to gel layer.

Acoustic Reflex

Protective reflex where middle ear muscles contract to dampen loud sounds.

Conductive Hearing Loss

Hearing loss due to problems in outer or middle ear (sound conduction).

Sensorineural Hearing Loss

Hearing loss due to damage to hair cells or auditory nerve.

Vertigo

Sensation of spinning or dizziness from vestibular system dysfunction.

Tinnitus

Perception of ringing or buzzing in ears, often from hair cell damage.

Eustachian Tube

Canal connecting middle ear to throat; equalizes air pressure.

Frequency

The pitch of a sound, measured in Hertz (Hz).

Amplitude

The loudness of a sound, measured in decibels (dB).