The osseous spiral lamina consists of two plates of bone, and between these are the canals for the transmission of the filaments of the

acoustic nerve The cochlear nerve (also auditory nerve or acoustic nerve) is one of two parts of the vestibulocochlear nerve, a cranial nerve present in amniotes, the other part being the vestibular nerve. The cochlear nerve carries auditory sensory information ...

. 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. Structure ...

is thickened to form the limbus spiralis (or limbus laminæ spiralis), this ends externally in a concavity, the

sulcus spiralis internus 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 spa ...

, which represents, on section, the form of the letter C.

References

External links

* http://www.anatomyatlases.org/MicroscopicAnatomy/Section16/Plate16311.shtml * http://www.med.uiuc.edu/histo/small/atlas/objects/103.htm Ear {{Anatomy-stub