10 U.S. NATIONAL MUSEUM BULLETIN 2 73 



posterior and lower borders of the pterygoid wing and more orally 

 from the inferior of the palatine pyramid. Some fibers of the muscle 

 actually override these edges and appear in the infratemporal fossa. 

 Insertion is by both fleshy and tendinous components on the deep 

 surface of the angle and ramus (fig. 2) over a wide quadrilateral area 

 bound below by the basis mandibulae, behind by the dorsal margin 

 of the ramus, and in front by the digastric fossa, the mylohoid, and 

 associated sulcus for the nerve. The upper limit Ues at a certain dis- 

 tance from the fossa for the lateral pterygoid. One to three bony 

 ridges of variable development are present within the area and 

 correspond to the attachment of a like number of intramuscular 

 tendinous strands. This description agrees with those of other authors 

 who studied the muscle in this genus (Sirena, 1871; Starck, 1933). 

 Starck (1933), in addition, found it to be divided into a lateral and a 

 medial larger part. Fibers of the first were said to be less oblique. 

 Nerve supply: A small branch is given off to both the medial 

 pterygoid and tensor veli palatini from the undivided mandibular 

 nerve. 



Function: Elevator and protractor of the mandible. 

 M. tensor veli 'palatini: This muscle is formed by two triangular 

 portions, a pars descendens and a pars horizontalis united at their 

 respective apices by an intermediate tendon (fig. 4). Pars descendens 

 has a firm origin by means of initially tendinous fibers from the antero- 

 lateral aspect of the auditory tube and by fleshy elements from the 

 inner surface of the pterygoid ala, between the hamulus and the base, in 

 front of the foramen ovale (fig. 5). Tubal fibers pass down and forward, 

 those from alar origin are almost vertical. They all converge into a 

 tendon which curves around the hook of the pterygoid. Its fibers spread 

 out within the soft palate to form the pars horizontahs. This meets in 

 the midline with that of the tensor of the other side and contributes to 

 the frame of the palatine aponeurosis. Pars descendens is laterally 

 related to the pterygoideus lateralis from which it is separated by the 

 otic ganglion and the maxillary artery with some of its branches. 

 Medially, it is separated from the levator veli palatini and pharyngeal 

 muscular coat by the highest fibers of the buccopharyngeal fascia. 

 This is reinforced by strong arciform fibers extended between the 

 sphenoid spine and the hamulus. 



Nerve supply: The same branch that innervates the medial 

 pterygoid muscle. 



Function : It tenses the soft palate. 



M. digastricus: The muscle has two well developed bellies con- 

 nected by an intermediate tendon. It extends from the mastoid region 

 to the inner surface of the mandible. Origin of the posterior belly is 

 by mixed fleshy and tendinous fibers firmly attached to the digastric 



