adult ptilinal muscle transverse vertex muscle 2022-07-05T13:30:44Z Temporary muscle that lies underneath the adult dorsal head (vertex) and extends transversely between the compound eyes. The contraction of this muscle layer diminishes the volume of the head. As with other temporary eclosion muscles, it soon degenerates and is not found in older flies. fly_anatomy.ontology FBbt:00058812 temporary eclosion muscle