Structure and Development - Arises from the temporal fossa and deep part of temporal fascia - Passes medial to the zygomatic arch - Inserts onto the coronoid process of the mandible - Covered by the temporal fascia - Accessible on the temples and can be seen and felt contracting - Derived from the first pharyngeal arch in development - Has a complex structure - Sarcomeres are a consistent length - Larger muscle fibers vary in length within the muscle and between individuals

Blood and Nerve Supply - Receives blood supply from the deep temporal arteries - Anastomoses with the middle temporal artery - Controlled by the third branch of the trigeminal nerve - Supplied by the deep temporal nerves - At least 6 smaller branches recruit muscle fibers - Recruitment of motor units maximizes contractile strength

Function - Most powerful muscle of the temporomandibular joint - Can be divided into anterior and posterior parts - Anterior portion elevates the mandible (closing the mouth) - Posterior portion retrudes the mandible - Middle portion used for both elevation and retraction, as well as lateral movement of the mandible

Clinical Significance - Involved in jaw pain and headaches - Overwork of the temporalis muscle can result in pain - Bruxism and jaw clenching can lead to temporalis muscle overuse - Myotendinous rupture of the temporalis muscle can occur during a seizure - Extreme clenching of the jaw during a seizure can cause the rupture - Temporalis muscle may be used in reconstructive surgery of the mouth - Incisions during pterional craniotomy are chosen based on ease of reattaching the temporalis muscle

Additional Information - Temporal muscle (red) - Muscles of head and neck - Deep dissection of temporal muscle - Mummification process - References to relevant studies and publications