Mammalia: Skin, Muscles, Skeleton 



601 



laiyl 



occ.b7 s : Cocc 



B 



Fig. 465. Dog skull. (A) Dorsal view. (B) Ventral view. (Cav.gl) Fossa for 

 articulation of lower jaw; (C.occ.) occipital condyle; (F) frontal; (Finf) infraorbital 

 foramen; {Jg) jugal (malar); (Jm) premaxillary; (L) lacrimal; (M) maxillary; 

 (TV) nasal; {Occ.bas.) basioccipital; (P, in A) parietal; (P, in B) palatine; (Pjt) 

 zygomatic process of temporal; {PI) pterygoid; {Sph) alisphenoid; {Sph') basi- 

 sphenoid; {Sph") presphenoid; {Sg.occ) supraoccipital ; {T) tympanic bulla of 

 temporal; {Vo) vomer. (Courtesy, Wiedersheim : "Grundriss der vergleichenden 

 Anatomie der Wirbeltiere," Jena, Gustav Fischer.) 



a strong process of the squamosal. The middle span of the arch is the 

 jugal, in mammals known as the "malar." This remnant of a tem- 

 poral arcade is called the zygomatic arch. In the anapsid skull the 

 great muscles which elevate the lower jaw occupy the space between 

 the side of the cranium and the temporal arcade. In the mammal the 

 masseter muscle extends from the zygomatic arch to the lower jaw 

 (Figs. 454, bottom; 460). The large space between the arch and the cra- 

 nial wall is occupied by the temporalis, a bulky muscle which arises 

 from an extensive area on the temporal region of the cranium (Fig. 460) 

 and inserts on a prominent dorsal coronoid process (Fig. 4365) of the 

 lower jaw. When the mouth is closed, the coronoid process, surrounded 

 on all sides by the muscles which attach to it, extends up into the 

 temporal space. Therefore the outer surface of the masseter (cheek- 

 muscle) and the considerable area of the temporalis extending above 

 it are covered externally only by the skin and some thin sheets of 



