38 



bulletin: museum of comparative zoology. 



The innervation of the two preceding muscles is from the ventral 

 ramus of the first spinal nerve, which passes between m. sterno- 

 hyoideus and m. omohyoideus to supply both (Plate 7, fig. 22; Plates 

 2, 3). 



4. Muscles of the Jaw and Neck. 



M. pferygo-mandibidaris (Bradley). This is the muscle (Plates 5, 

 6, figs. 14-19, pt-md.) generally described as the external ptery- 

 goid. It is best seen from the ventral side with the roof of the pharynx 

 removed (Fig. 7). Its origin is along the entire posterior edge of the 

 main portion of the pterygoid bone, and chiefly by means of a strong 

 tendinous fascia that is continuous with the muscle sheath on the 



pl-md. 



pt-5ph.]i.- 



plpar. 



prcplqd ' jitjphp ba'occ. 



Fig. H. Fig. I. 



Fig. H. — Right lateral aspect of a portion of the skull to show attachments 

 of the deeper muscles, m. pterygo-parietalis and m. pterygo-sphenoidalis 

 posterior. 

 Fig. I. — Ventral aspect of a portion of the right half of the skull with man- 

 dible removed to show m. pterygo-mandibularis. This really covers the 

 m. -J pterygo-sphenoidalis posterior, but is slightly displaced to show the 

 position of the latter. 



ventral side. The most posterior[fibers have a fleshy origin along the 

 posterior wing of the pterygoid. The insertion of this muscle is on 

 the angulare and articulare over the entire ventral plate as well as on 

 the dorsal face of the median extension of these bones (Plate 6, fig. 19). 

 Those muscle fibers that pass around the ventral side of the jaw to an 

 extreme lateral insertion have their origin along the surface of the 

 tendinous sheath instead of extending to the pterygoid bone. 



The innervation (Plate 3, fig. 6, pt-md.) is from a ventral twig of the 

 same ramus of mandibular V which innervates the deeper portion of 

 the m. pterygoideus. 



M. pterygo-sphenoidalis posterior {pt-sph. p., Figs. H, I, PlateT6, 

 figs. 16, 17) of Bradley. The following is Bradley's (:03, p. 478) 



