See also Labyrinth, an article treating the mythical maze that imprisoned the Minotaur.
The labyrinth is a system of fluid passages in the inner ear, comprising the semicircular canals and the vestibule, which provides the sense of balance. It is named by analogy with the mythical maze that imprisoned the Minotaur, because of its appearance.
Three structures of the labyrinth, the semicircular canals, let us know when we are in a rotary (circular) motion. The semicircular canals, the superior, posterior, and horizontal, are filled with fluid. Motion of the fluid tells us if we are moving. The semicircular canals and the visual and skeletal systems have specific functions that determine an individual's orientation. The vestibule is the region of the inner ear where the semicircular canals converge, close to the cochlea (the hearing organ). The vestibular system works with the visual system to keep objects in focus when the head is moving. Joint and muscle receptors also are important in maintaining balance. The brain receives, interprets, and processes the information from these systems that control our balance.
Interference with or infection of the Labyrinth can result in a syndrome of ailments called Labyrinthitis. The symptoms of Labrynthitis include temporary nausea, disorientation, vertigo, and dizziness. Labyrinthitis can be caused by viral infections, bacterial infections, or physical blockage of the inner ear.
Stimulation of the hair cells in the vestibularapparatus is associated with the sense of hearing.
Stimulus of the vestibularapparatus is mediated largely through histamine and acetylcholine receptors.
Located within the inner ear, the vestibularapparatus is the sense organ that detects linear and angular accelerations of the head and relays this information to brainstem nuclei that elicit appropriate postural and ocular responses.
The vestibularapparatus is the nonauditory portion of the inner ear.
The vestibular nuclei give rise both to the vestibulospinal tracts, which play a role in movement and posture, to be discussed in Chapter 16, and to connections with cranial nerve nuclei III, IV, and VI and motoneurons of the neck by way of the medial longitudinal fasciculus (MLF).
Disturbances of vestibular function include motion sickness, a failure to adapt to repeated movements; vertigo, a false sense of rotation due to irritation of vestibular nerve fibers; and short-term disturbances of equilibrium associated with destruction of one or both labyrinths.
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