The is a thin quadrilateral muscle, occupying the interval between the
Maxilla and the
Mandible at the side of the face. Its action is to pull back the angle of the mouth and to flatten the cheek area.
It arises from the outer surfaces of the
Alveolar Processes of the maxilla and mandible, corresponding to the three
Molar Teeth ; and behind, from the anterior border of the pterygomandibular raphé which separates it from the
Constrictor Pharyngis Superior .
The fibers converge toward the angle of the mouth, where the central fibers intersect each other, those from below being continuous with the upper segment of the
Orbicularis Oris , and those from above with the lower segment; the upper and lower fibers are continued forward into the corresponding lip without decussation.
