MUSCLES OF MASTICATION
Four pairs of muscles are considered the major muscles of mastication. These
muscles are used for chewing and swallowing food. The masseter, the temporalis, and
the medial pterygoid raise the mandible against the maxilla with considerable force.
The fourth pair of muscles, the lateral pterygoids, act to thrust the mandible forward.
Acting with other muscles, it opens the mouth. See figures 2-9, 2-10, and 2-11.
a. Masseter. The masseter is one of the primary muscles that close the jaws
and exerts pressure on the teeth, particularly in the molar region.
b. Temporalis. The temporalis muscle is a fan-shaped muscle that attaches
along the side of the head. Like the masseter, it closes the jaws. Because of its
posterior horizontal fibers, it can also pull the mandible backward.
c. Medial Pterygoid. Together with the masseter and temporalis muscles, the
medial pterygoid muscle elevates the mandible against the maxilla. The combined
action of the three muscles creates a very strong masticating pressure between the
opposing maxillary and mandibular posterior teeth.
Figure 2-10. Medial and lateral pterygoid muscles.