294 THE MUSCLES AND FASCIAE OF THE HEAD AND NECK. 



anterior auricular muscles ; and from the temporal muscle, at the lower part, by a 

 layer of fat. 



The temporal muscle (fig. 269, 1) is fan-shaped, and arises from the whole 

 surface of the temporal fossa, with the exception of the anterior or malar wall, and 

 from the deep surface of the temporal fascia, except close to the zygomatic arch : 

 some of its posterior fibres arising from this fascia blend with the deep fibres of the 

 masseter muscle. The direction of the anterior fibres is nearly vertical, that of the 

 middle fibres oblique, and that of the posterior fibres at first almost horizontal. The 

 fibres converge as they descend, and terminate mostly in a tendon, which is 

 implanted into the upper and anterior borders of the coronoid process of the lower 

 jaw, while the deeper fibres have a fleshy insertion into the inner side of the process, 

 reaching down to the union of the ramus and body of the jaw. 



Relations. The upper part of the muscle is closely covered by the temporal fascia ; the 

 lower and anterior part is embedded in fat continuous with that which lies between the 



Fig. 274. THE PTERYGOID MUSCLES 



FROM OUTSIDE. (GK D. T.) ^ 



The masseter muscle, the greater 

 portion of the zygomatic arch, the tem- 

 poral muscle with the coronoid process, 

 and a large part of the ramus of the 

 jaw have been removed. 1, external 

 pterygoid ; the figure is placed on the 

 lower head ; 2, internal pterygoid. 



masseter and buccinator muscles. 

 Between the muscle and the bone of 

 the temporal fossa are the deep tem- 

 poral arteries and nerves, which 

 penetrate its substance. In contact 

 with the deep surface of the muscle 

 near its insertion the buccal nerve 



descends, and at the posterior border of the insertion the masseteric nerve and artery 



emerge. 



The internal pterygoid muscle arises from the pterygoid fossa, its fibres, 

 tendinous and fleshy, being attached mostly to the inner surface of the external 

 pterygoid plate and to that portion of the tuberosity of the palate bone which is 

 situated between the pterygoid plates, and by a second smaller slip, lying outside the 

 external pterygoid muscle, from the outer surface of the tuberosities of the palate 

 and superior maxillary bones. Thence it is directed downwards, with an inclination 

 backwards and outwards, and is inserted into the rough mark on the inner side of 

 the ramus of the lower jaw between the angle and the dental foramen. 



Relations. The internal pterygoid muscle is placed on the inner side of the ramus of the 

 jaw, somewhat in the same manner as the masseter lies on the outer side. Between the 

 external surface of the muscle and the ramus of the mandible are the internal lateral 

 ligament, the internal maxillary vessels with their inferior dental branches, and the inferior 

 dental and lingual nerves ; and at its upper part the larger head is crossed by the external 

 pterygoid muscle. Its inner surface is in contact with the tensor palati muscle, with the 

 superior constrictor of the pharynx, and with the ascending palatine artery. 



The external pterygoid muscle, occupying the zygomatic fossa, arises by two 

 fleshy heads placed close together, the superior of which is attached to the zygomatic 

 surface of the great wing of the ^phenoid, and to the infratemporal crest which 

 separates that surface from the temporal fossa ; while the inferior, which is larger, 

 is attached to the outer surface of the external pterygoid plate. The fibres from 



