The temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. The TMJ is a bilateral synovial articulation between the mandible and temporal bone.The name of the joint is derived from the two bones which form the joint: the upper temporal bone which is part of the cranium (skull), and the lower jawbone or mandible.ach TMJ is classed as a ginglymoarthrodial joint since it is both a ginglymus (hinging joint) and an arthrodial (sliding) joint. The condyle of the mandible articulates with the temporal bone in the mandibular fossa. The mandibular fossa is a concave depression in the squamous portion of the temporal bone.