Inner ear

The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:

The inner ear is found in all vertebrates, with substantial variations in form and function. The inner ear is innervated by the eighth cranial nerve in all vertebrates.

Structure

The labyrinth can be divided by layer or by region.

Bony vs. membranous

The bony labyrinth, or osseous labyrinth, is the network of passages with bony walls lined with periosteum. The membranous labyrinth runs inside of the bony labyrinth. There is a layer of perilymph fluid between them. The three parts of the bony labyrinth are the vestibule of the ear, the semicircular canals, and the cochlea.

Interior

Interior may refer to:

See also

Ear

The ear is the organ of the sense of hearing, and in mammals is also an organ of balance. In mammals, the ear is usually described as having three parts—the outer ear, middle ear and the inner ear. The outer ear consists of the auricle or pinna, and the ear canal. The middle ear includes the tympanic cavity and the three ossicles. The inner ear consists of the bony labyrinth which contains the semicircular canals, and the utricle and saccule of the vestibular system, to do with balance, and the cochlea a part of the auditory system.

The ear develops from the first pharyngeal pouch and six small swellings that develop in the early embryo called otic placodes, which are derived from ectoderm.

A number of conditions may relate to the ear, including hearing loss, tinnitus and balance disorders including vertigo, however these may also relate to diseases affecting the pathways in the brain relating to hearing and balance.

Although the entire organ is considered as the ear, it is often just referred to as the visible outer part. In most mammals, the visible ear is a flap of tissue that is also called the pinna (or auricle in humans) and is the first stage in hearing. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization.