Labyrinth (inner ear)

For more uses of the word labyrinth, see Labyrinth (disambiguation)

The labyrinth is a system of fluid passages in the inner ear, including both the cochlea which is part of the auditory system, and the vestibular system which provides the sense of balance. It is named by analogy with the mythical maze that imprisoned the Minotaur, because of its appearance.

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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.

Pathology

Interference with or infection of the labyrinth can result in a syndrome of ailments called Labyrinthitis. The symptoms of Labyrinthitis include temporary nausea, disorientation, vertigo, and dizziness. Labyrinthitis can be caused by viral infections, bacterial infections, physical blockage of the inner ear, or due to decompression sickness.

Anatomical details

Top image is antero-lateral and bottom image is postero-medial.

1. Lateral semicircular canal; 1’, its ampulla;
2. Posterior canal; 2’, its ampulla.
3. Superior canal; 3’, its ampulla.
4. Conjoined limb of superior and posterior canals (sinus utriculi superior).
5. Utricle. 5’. Recessus utriculi. 5”. Sinus utriculi posterior.
6. Ductus endolymphaticus.
7. Canalis utriculosaccularis.
8. Nerve to ampulla of superior canal.
9. Nerve to ampulla of lateral canal.
10. Nerve to recessus utriculi (in top image, the three branches appear conjoined). 10’. Ending of nerve in recessus utriculi.
11. Facial nerve.
12. Lagena cochleæ.
13. Nerve of cochlea within spiral lamina.
14. Basilar membrane.
15. Nerve fibers to macula of saccule.
16. Nerve to ampulla of posterior canal.
17. Saccule.
18. Secondary membrane of tympanum.
19. Canalis reuniens.
20. Vestibular end of ductus cochlearis.
21. Section of the facial and acoustic nerves within internal acoustic meatus (the separation between them is not apparent in the section).

See also

• Cochlea
• Vestibular system
• Inner ear
• Endolymph