94 ANNALS NEW YORK ACADEMY OF SCIENCES 



MUSCLES OF THE DEPRESSOR OR DIGASTRIC GROUP 

 {INXERVATED BY YIl) 



Depressor mandibultp. 



MUSCLES OF THE ADDUCTOR OR TEMPORAL GROUP 

 (IXXERVATED BY Y^) 



Capiti-m an dibularis. 



{a) Capiii-mandibularis superficialis (C. m. s.). — This is the outer 

 slip of the temporal mass, which does most of the work in the closing of 

 the jaw. It arises on the parietal, squamosal, quadrate and quadrato- 

 jugal and is inserted in the suprameckelian fossa, extending forward into 

 the dentary. It fills the region of the skull behind the pterygoids. The 

 large external fenestra of the niandi[)le gives the muscle room for expan- 

 sion. The superficial layer (masseter) is subdivided into several layers, 

 one being attached to the surangular. 



(h) C a pit i-ni an dibularis mcdiiis (C. m. m.). — This is the smaller of 

 the slips of the mass. It extends down on the inner side of the capiti- 

 mandibularis mass, arising on the bones surrounding the supratemporal 

 fossa, into which it extends. It arises on the i^arietal, squamosal and 

 postfrontal. Its insertion is on the coronoid, where it curves around the 

 anterior edge of the capiti-mandibularis superficialis and extends under 

 this slip to the mandible. The mandibular nerve separates it from the 

 superficial slip. A small capiti-mandibularis profundus (pterygoideus 

 post. Lubosch) attaches to the tendon of this muscle. Lubosch (1914, p. 

 699) says: 



Sehen wir vom Masseter und Pterygoideus anterior ab, so inseriert der sehr 

 schwaclie. zweischichtige Temporalis mit einer kraftigen kurzeu Sehne am Com- 

 plementare. Ein Tell der Fasern endet an einer knorpelharten Zwischenselme. 

 Von dieser Zwischensehne entspringen fraglichen Muskelportionen. welche 

 ihrerseits zum Pterygoideus posterior geliuren. 



(c) Capili-inandihularis profundus (C. m. p.). — This small muscle 

 which joins the temporal mass is given this name, as it is assumed to 

 belong to the inner layer of the temporal mass. 



Pterygoideus anterior. — This anterior slip arises on the palatine, 

 maxilla, pterygoid and transverse (ectopterygoid), extending over the 

 floor formed by these bones and digging into the maxillae. It extends 

 inward to the limits of the narial passage. This muscle is the same as 

 the great pterygoid nniscle in Chelydra and is typical of the monimostylic 

 reptiles. In the crocodile, however, it has a much greater forward ex- 

 tension. 



