Innerörat

Innerörat, or the inner ear, is the part of the ear located within the petrous portion of the temporal bone. It comprises the cochlea, responsible for hearing, and the vestibular apparatus, responsible for balance. The cochlea is a spiral, snail-shaped canal containing the organ of Corti on the basilar membrane and the tectorial membrane; hair cells transduce mechanical vibrations into neural signals that travel via the spiral ganglion to the cochlear nerve, a component of cranial nerve VIII. Perilymph surrounds the membranous labyrinth, while endolymph fills it.

The vestibular apparatus includes the utricle and saccule, which detect linear acceleration, and the semicircular canals, which detect angular acceleration, with hair cell–bearing cristae within the ampullae. The inner ear is innervated by the vestibulocochlear nerve (cranial nerve VIII) and receives its blood supply primarily from the labyrinthine artery, a branch of the basilar or anterior inferior cerebellar artery (AICA).

Functionally, the inner ear converts sound vibrations into neural impulses and provides sensory input for balance and spatial orientation, including gaze stabilization via the vestibulo-ocular reflex. Developmentally, it originates from the otic placode and resides within the temporal bone.

Clinical relevance includes disorders that cause sensorineural hearing loss and vertigo, such as Menière’s disease, vestibular neuritis, labyrinthitis, and benign paroxysmal positional vertigo. Diagnostic approaches encompass audiometry, otoacoustic emissions, vestibular tests (e.g., videonystagmography), and imaging like MRI; treatments vary by condition and may involve hearing aids or cochlear implants, diuretics for Menière’s disease, and vestibular rehabilitation.