Temporalis muscle

At a glance

English

Temporalis muscle

Latin (TA2)

Musculus temporalis

System

Muscle

Region

Head

Side

Paired, left and right

Arises from

The frontal bone, parietal bone, sphenoid bone and temporal bone

About the temporalis muscle

Temporalis occupies the temporal fossa, the shallow hollow on the side of the skull above the zygomatic arch. Its fibres spread out like an open fan over the side of the head and gather into a thick tendon below. Together with masseter and the two pterygoid muscles it makes up the group that moves the mandible during chewing, and it is the strongest muscle acting on the temporomandibular joint.

The fibres take origin from the whole floor of the fossa, where the frontal, parietal, sphenoid and temporal bones meet, and from the deep surface of the dense temporal fascia that roofs it over. They converge downwards, pass deep to the zygomatic arch, and end on the mandible's coronoid process. The tendon reaches down along the front edge of the ramus as far as the retromolar fossa, just behind the last lower molar. You can feel the muscle harden at the temple each time you clench your teeth.

Fibre direction decides what each region does. The front fibres are nearly vertical and lift the mandible to close the mouth. The rear fibres run almost horizontally above the ear and draw the jaw backwards after it has been pushed forward. The intermediate, oblique fibres help with both, and one muscle acting alone helps swing the jaw to the side when grinding food. Like the other chewing muscles it develops from the first pharyngeal arch and so is served by the mandibular division of the trigeminal nerve.

Clinically, temporalis is a common source of temple headache and jaw pain, especially in people who clench or grind their teeth at night. Very forceful clenching, as can happen during a seizure, may tear it where muscle meets tendon on the coronoid process. Dentists keep lower dentures short of the retromolar fossa so that the contracting tendon does not rub the gum. Surgeons often harvest the overlying temporal fascia as graft material when repairing a perforated eardrum.

Attachments, action and supply

Origin

Floor of the temporal fossa (frontal, parietal, sphenoid and temporal bones) and the deep surface of the temporal fascia.

Insertion

The mandible's coronoid process and the front border of the ramus down to the retromolar fossa.

Action

Elevates the mandible to close the mouth; posterior fibres retract it; one side helps move the jaw sideways.

Nerve supply

Deep temporal nerves from the mandibular division of the trigeminal nerve (CN V3).

Blood supply

Anterior and posterior deep temporal arteries from the maxillary artery, joined by the middle temporal artery.