has part has part has_part characteristic of part of has modifier abnormal masticatory muscle morphology abnormal masseter muscle morphology any structural anomaly of the masticatory muscle of posterior cheek with origin from the inferior border and medial surface of the zygomatic arch, with insertion into the lateral surface of the ramus of the mandible, with nerve supply from the masseteric nerve, and whose action closes the jaw during chewing MPheno.ontology MP:0004235 morphology abnormal masseter muscle