Anatomy of the Inner Ear

Timothy C. Hain, MD Page last modified: January 5, 2008

While there are several other surveys of inner ear anatomy, we have diffidently here set out to put the content in our lecture on this subject on the web.

Overview of peripheral anatomy

• Mechanical sensors (canals and otoliths) respond to angular and linear movement
  • The semicircular canals are very small rings -- about 1 cm in diameter. The image below taken from a CT scan shows that the anterior canal is less than 1 cm - -smaller than a dime !
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  • There are three semicircular canals - -the anterior, superior and horizontal. Between the three canals the brain can determine rotational velocity in three dimensions.
  • There are also two otolith organs (click here for more). The otoliths respond to linear acceleration such as gravity or changing velocity of movement in a straight line.
• Cochleo-Vestibular(8th) cranial nerve (click here for an animation if viewing on the site DVD)
• Spiral (cochlear) and Scarpa's (vestibular) ganglion
• Brainstem nuclei

Next --> Tour the ear