On the upper plate of that part of the lamina which is outside the
vestibular membrane, the
periosteum
The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones.
Structu ...
is thickened to form the
spiral limbus, this ends externally in a concavity, the sulcus spiralis internus, which represents, on section, the form of the letter C.
References
External links
Histology at uc.edu
Ear
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