Publication:

The human cochlea - anatomical aspect: a brief review

The inner ear or the labyrinth performs the function of hearing and balance. It consists of a bony and a membranous labyrinth. Bony labyrinth consists of three parts – the vestibule, cochlea and the semicircular canals. Membranous labyrinth consists of the cochlear duct, the utricle and saccule, the three semicircular ducts, and the endolymphatic duct and the sac. The membranous labyrinth contains fluids which are in a state of dynamic equilibrium with the intracranial cerebrospinal fluid. Basilar membrane displacements result in electrolyte alterations and thus generate nerve impulses. Scala media is filled with endolymph that can be distinguished by its ion composition that is much like an intracellular character with respect to its potassium content. Scala tympani and scala vestibuli are filled with perilymph containing an extracellular-like ion composition and communicate at the apex of the cochlea via the helicotrema. The fluid contained within the tunnel of Corti and Nuel's spaces within the sensory epithelium resembles composition of the perilymph. The disturbance in the milieu interior is consequent to auditory and vestibular impairments. The unique anatomy of the membranous labyrinth shall be elaborated.