Vestibular aqueducts

Vestibular aqueducts are narrow, bony canals that travel from the inner ear to deep inside the skull (see figure). The aqueducts begin inside the temporal bone, the part of the skull just above the ear. The temporal bone also contains two sensory organs that are part of the inner ear. These organs are the cochlea, which detects sound waves and turns them into nerve signals, and the vestibular labyrinth, which detects movement and gravity. These organs, together with the nerves that send their signals to the brain, work to create normal hearing and balance. Running through each vestibular aqueduct is a fluid-filled tube called the endolymphatic duct, which connects the inner ear to a balloon-shaped structure called the endolymphatic sac.

Source: NIDCD (NIH)1

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What are vestibular aqueducts?

Vestibular aqueducts are narrow, bony canals that travel from the inner ear to deep inside the skull (see figure). The aqueducts begin inside the temporal bone, the part of the skull just above the ear. The temporal bone also contains two sensory organs that are part of the inner ear. These organs are the cochlea, which detects sound waves and turns them into nerve signals, and the vestibular labyrinth, which detects movement and gravity. These organs, together with the nerves that send their signals to the brain, work to create normal hearing and balance. Running through each vestibular aqueduct is a fluid-filled tube called the endolymphatic duct, which connects the inner ear to a balloon-shaped structure called the endolymphatic sac.

Recent studies indicate that a vestibular aqueduct is abnormally enlarged if it is larger than one millimeter, roughly the size of the head of a pin. This is called an enlarged vestibular aqueduct, or EVA; the condition is also known as a dilated vestibular aqueduct or a large vestibular aqueduct. If a vestibular aqueduct is enlarged, the endolymphatic duct and sac usually grow large too. The functions of the endolymphatic duct and sac are not completely understood. Scientists believe that the endolymphatic duct and sac help to ensure that the fluid in the inner ear contains the correct amounts of certain chemicals called ions. Ions are needed to help start the nerve signals that send sound and balance information to the brain.

Source: NIDCD (NIH)2

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Vestibular Aqueduct: A small bony canal linking the vestibule of the inner ear to the posterior part of the internal surface of the petrous Temporal Bone. It transmits the endolymphatic duct and two small blood vessels.3

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References

  1. Source: NIDCD (NIH): nidcd.nih.gov/ health/ enlarged-vestibular-aqueducts-and-childhood-hearing-loss
  2. ibid.
  3. Source: MeSH (U.S. National Library of Medicine)
  4. Source: NIDCD (NIH): nidcd.nih.gov/ health/ enlarged-vestibular-aqueducts-and-childhood-hearing-loss

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