4 U.S. NATIONAL MUSEUM BULLETIN 2 73 



Nerve supply: The anterior division of the mandibular nerve. 



Function : Elevator and retractor of the mandible. 



M. masseter (fig. 1) : This strong muscle is incompletely divided 

 from behind forward by a sagittal cleft into a superficial and a deep 

 portion. They are united into a single mass only in the anterior half 

 of the belly. 



Pars superficialis is the larger of the two parts. Its origin is on the 

 external surface and lower margin of the entire zygomatic arch. 

 Anterior fibers are initially tendinous and firmly anchored to the bone. 



Figure 1. — Masticatory and facial muscles (1, capsule of temporomandibular joint; 2, 

 aponeurotic part of the pars superficialis in continuity with the capsule of the joint; 3, m. 

 masseter; 4, deep layer of m. buccinator; 5, its intermediate layer; 6, its superficial vertical 

 layer; 7, m. orbicularis oris; 8, m. caninus; 9, m. maxillo-naso-labialis; 10, m. temporalis). 



