a group of four paired muscles in man and animals, providing movement of the lower jaw (mandible) during mastication. The masseter muscle, or the masticatory muscle proper, originates from the zygomatic arch and the temporal fascia and attaches to the angle of the mandible. The temporal muscle, originating from the temporal bone and the temporal fascia, attaches to the coronoid process of the mandible. The pterygoideus internus and externus muscles are deeperlying, originating from the sphenoid bone at the base of the skull; the former attaches to the neck of the condyloid process of the mandible, and the latter to the interior surface of the angle of the mandible.

In addition to providing masticatory movement, the masticatory muscles work with the mimetic muscles to articulate speech, facial expression, and yawning. Several neck muscles—the geniohyoid, mylohyoid, and digastric—also provide movement during mastication. Blood is supplied to the masticatory muscles by branches of the carotid artery. Innervation is provided by the third branch of the trigeminal nerve.