[TA] head of origin from the infratemporal surface and crest of the greater wing of the sphenoid; this part of the muscle attaches to the discocapsular system (fibrous layer of the joint capsule and articular disc) of the temporomandibular joint and has been determined by electromyography to be active during both protrusion and retrusion of the mandible serving in both to ensure that the disc moves in concert with the excursion of the head of the mandible. SYN: caput superius musculi pterygoideus lateralis [TA], superior head of lateral pterygoid (muscle)*.