280 



MUSCLES OF THE HEAD AXD NECK. 



is inserted into the angle and the inner snrflice of the ramus of the jaw 

 as high as the dental foramen. 



Bdations. — The intemal i^terygoid muscle is placed on the inner side of the 

 ramus of the jaw, somewhat in the same manner as the masseter lies on the 

 outside. Between the external surface of the muscle and the ramus of the 

 maxilla are the internal lateral ligament and the internal maxillary vessels, with 

 the dental artery and nerve ; and at its upper part the muscle is crossed by the 

 external pterygoid muscle. Its inner sm-face is in contact, whilst in the ptery- 

 goid groove, with the tensor palati muscle, and lower down with the superior 

 constrictor of the pharjaix. 



Fig. 20(3. 



A 



- y 



Fig. 206, — Views of the Pterygoid I\Iuscles — A, from the outer side ; B, from 



THE INNER SIDE. \ 



1 , external pterygoid ; 2, internal pterygoid — the outer surface in A, the inner surface 

 inB. 



The external pterygoid nmscle, occupying the zygomatic fossa, 

 arises by two fleshy heads placed close together, the superior of which 

 is attached to that part of the external surface of the great wing of the 

 sphenoid bone which looks into the zygomatic fossa, and to the ridge 

 which separates that surface from the temporal fossa; while the in- 

 ferior, which is larger, is attached to the outer surface of the external 

 pterj^goid plate, and to the tuberosities of the palate and upper max- 

 illary bones. The fibres from both heads pass backwards, and converge 

 to be inserted into the fore part of the neck of the condyle of the lower 

 jaw, and into the interarticular fibro-cartilage of the temporo-maxillary 

 articulation. 



Hi'lationx. — The intemal maxillary arteiy is usually placed on the outer surface 

 of this muscle, passing thence between the heads of origin ; while the buccal 

 neiwe issues fi'om between those heads. The deep siu'face rests against the 

 upper part of the intemal pterygoid muscle, whose direction it crosses, also the 

 intemal lateral ligament of the lower jaw, the inferior maxillary nerve, and the 

 middle meningeal artery. The upper border is in contact with the great wing of 

 the sphenoid bone, and is crossed by the deep temporal nerve and arteries. 



Varieties. — The jftei'i/'/oideit.'; 2>>'e>j)?-iii.'i (Henle). This is nearly a vertical slip, 

 which passes from the crest of the great wing of the sphenoid to the tuberosity 

 of the palate bone or to the posterior margin of the external pterygoid plate. In 

 some cases reported by Mr. Wagstaffe (Joum. of Anat. vol. v., p. 2S1), in which 

 this slip was present, the maxillary head of the external i^terygoid was absent, 

 and some of the ordinary fibres arose from those vertical bands. Another fonn 



