Otic capsule

Last revised by Craig Hacking on 7 Mar 2019

The otic capsule or osseous (bony) labyrinth refers to the dense bone of the petrous temporal bone that surrounds the membranous labyrinth of the inner ear. It is surrounded by the less dense and variably pneumatized petrous apex and mastoid part of the temporal bone.

From anterior to posterior, the osseous labyrinth is comprised of:

It is lined by periosteum. As the membranous labyrinth is slightly smaller than the osseous labyrinth, the two are separate by perilymph, which does not communicate with the endolymph contained in the membranous labyrinth.

There are 4 openings:

Related pathology

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Cases and figures

  • Figure 1: otic capsule (blue arrow)
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  • Case 1: PTB fracture involving otic capsule
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