PHYSIOLOGY, AND PATHOLOGY OF THE CHIMPANZEE. 



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of both muscles are continuous on the root of the pinna. Slips 

 from the platysnia (Pla) go to the back of the auricle, and a 

 small tragicus (Trag) is present. 



The masseter (text-fig. 28 A) consists of the usual superficial 

 and deep parts. The former (S.P.M) arises from the lower 

 borders of the malar bone and anterior two-thirds of the zygoma ; 



Text-figure 28. 



Muscles of mastication ; A : Masseter ; B : Attachments of muscles to the 

 mandible ; C : Muscles, nerves and vessels below the labial mucous 

 membrane. B. A. and BUG : buccal artery and buccinator muscle ; I.O.N., 

 L.B.N., and M.B.T : infra-orbital, long buccal, and mental nerves ; L.L. and 

 U.L : lips; M.I. and M.M ; incisive and mentalis muscles; L.P. and S.P : 

 labial and salivary papillae ; S.P.F : suctorial pad of fat. Other letters as in 

 text-fig. 26. 



the fibres pass downwards and backwards to be inserted into the 

 margin of the lower border, angle, and lower half of the posterior 

 border of the ramus of the mandible. Between the two parts is 

 a strong fascial sheet into which fibres of both parts are inserted. 

 The deep part (D.P.M) arises from the entire length of the deep 



