e. Other Muscles of Mastication. The buccinator is an important facial muscle
used in mastication. There are also four assisting muscles of mastication listed below.
(1) Buccinator. The primary action of the buccinator (or cheek) muscle is to
compress the cheek, thus moving food between the teeth during the chewing or
grinding process. See figure 2-11.
(2) Assisting muscles. The mouth is opened by the lateral pterygoid
muscle, assisted by the digastric, mylohyoid, geniohyoid, and genioglossus muscles
(see figure 2-11). See figure 2-8 for the areas of attachment of these assisting muscles
TEMPOROMANDIBULAR JOINT (TMJ)
The temporomandibular joint (TMJ) makes possible the various movements of
the mandible (see figure 2-12). It allows for the up, down, forward, backward, and side
to side movements. All movements of the mandible and the functioning of the teeth are
closely associated with the TMJ. The structures of the TMJ and some information about
how they function follow.
Figure 2-12. Temporomandibular joint, lateral cross-section view.