part of part of organ part cochlear duct of membranous labyrinth lamina of spiral limbus spiral limbus lamina MA:0001191 spiral limbus Wikipedia:Limbus_laminae_spiralis limbus lamina spiralis limbus laminae spiralis osseae 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. On the upper plate of that part of the lamina which is outside the vestibular membrane, the periosteum is thickened to form the limbus spiralis (or limbus laminæ spiralis), this ends externally in a concavity, the sulcus spiralis internus, which represents, on section, the form of the letter C. [WP,unvetted]. UBERON:0002276 limbus laminae spiralis FMA:77721 EMAPA:35496