insideear

The inner ear, or labyrinth, is a fluid-filled structure within the temporal bone that supports hearing and balance. It consists of the bony labyrinth and the membranous labyrinth, which contain perilymph and endolymph respectively.

The bony labyrinth includes the cochlea, vestibule, and three semicircular canals. The membranous labyrinth lies within it and follows the same shape, filled with endolymph.

Hearing occurs in the cochlea. The organ of Corti sits on the basilar membrane; sound waves deflect the membrane, bending hair cells and converting mechanical energy into electrical signals carried by the auditory nerve.

Balance is mediated by the vestibular apparatus: the utricle and saccule detect linear motion and gravity; the semicircular canals detect angular motion via hair cells in their ampullae.

Fluids include perilymph surrounding the membranous labyrinth and endolymph within. Endolymph's high potassium is essential for transduction. Disturbances can cause Menière’s disease or other vestibular or sensorineural disorders.

Clinically, the inner ear is evaluated with audiometry and imaging; cochlear implants can bypass hair cell loss; vestibular rehabilitation addresses balance problems. Developmentally, the inner ear arises from the otic placode and differentiates prenatally, with ongoing maturation after birth.