The human ear (latin: auris) is a paired sensory organ responsible for the sense of hearing and balance. This complex anatomical structure is also referred to as the vestibulocochlear apparatus. Most of the structures of the vestibulocochlear apparatus are located inside the temporal bone of the skull.
The ear consists of three parts:
- external ear,
- middle ear,
- internal ear.
The first two parts conduct the sound vibrations to the internal ear, which contains the receptors of hearing and balance.
The external ear consists of the auricle and the external auditory meatus. The middle ear includes the tympanic cavity and the auditory tube that connects the tympanic cavity with the pharynx. At the deep end of the external acoustic meatus, separating the external ear from the tympanic cavity of the middle ear lies the tympanic membrane (eardrum).
The internal ear (or inner ear) is located within the petrous part of the temporal bone. It is formed by a bony labyrinth and a membranous labyrinth. The bony labyrinth of the inner ear consists of the vestibule, three semicircular canals and the cochlea. The membranous labyrinth is located within the bony labyrinth, and it includes two sacs (utricle and saccule), three semicircular ducts and the cochlear duct. The space inside the membranous labyrinth is filled with the endolymphatic fluid, while outside the membranous labyrinth the space is filled with perilymph.
The vestibulocochlear apparatus contains two types of receptors located in the inner ear: the organ of Corti for receiving the sound stimulus - located in the cochlear duct, and the receptors of the vestibular apparatus for appreciation of the impact of gravitation (static balance) - located in the utricle and saccule, and acceleration (kinetic balance) - located in the semicircular ducts.