orifice round window of inner ear EMAPA:19239 FMA:56932 GAID:878 MA:0002814 MESH:A09.246.631.246.814 UBERON:0002502 cochlear window fenestra cochleae fenestra rotunda round window round window of petrous part of temporal bone the opening on the medial wall of the middle ear leading into the cochlea, closed in life by the secondary tympanic membrane; serves to regulate fluid pressure in the inner ear uberon anatomical conduit mesoderm-derived structure neural crest-derived structure