TEMPORAL AND INFRATEMPORAL REGIONS 265 



mandible it is obvious that the mandible must be removed. 

 This will be done during the dissection of the temporal and 

 infratemporal regions, which must now be proceeded with. 



TEMPORAL AND INFRATEMPORAL REGIONS. 



Fascia Temporalis. The temporal fascia is a strong 

 glistening membrane which is stretched over the temporal 

 fossa, binding down the temporal muscle. Its upper margin 

 is attached to the upper of the two curved lines which 

 constitute the temporal ridge on the lateral aspect of the 

 skull, and anteriorly to the temporal line of the frontal 

 bone. As it approaches the zygomatic arch, it splits into 

 two laminae, which are separated from each other by a narrow 

 interval filled with fat. The two laminae are attached one to 

 the upper border of the zygomatic arch and the posterior 

 border of the zygomatic bone, and the other to the medial 

 surfaces of these two portions of bone. They can readily 

 be demonstrated by dividing the superficial layer close to its 

 attachment, and throwing it upwards ; by the handle of the 

 knife the attachment of the deep layer can then be made out. 

 In the upper part of its extent, the temporal fascia is com- 

 paratively thin and the fibres of the subjacent muscle may 

 be seen shining through it ; below, it is thicker, and owing 

 to the fat which is interposed between its laminae, it is 

 perfectly opaque. It is pierced immediately above the 

 posterior part of the zygomatic arch by the middle temporal 

 branch of the superficial temporal artery and by the middle 

 temporal vein (p. 157). 



Musculus Masseter. The masseter is a massive quadrate 

 muscle which covers the ramus of the mandible. Its 

 fibres are arranged in two sets a superficial and a deep. 

 The superficial part ofc-the muscle arises from the anterior two- 

 thirds of the lower border of the zygomatic arch, and its 

 fasciculi are directed downwards and posteriorly. The deep 

 part springs from the whole length of the medial aspect of the 

 zygomatic arch, and also from the posterior third of its lower 

 border. Its fibres proceed downwards and anteriorly. Only 

 a small piece of the upper and posterior part of this portion 

 appears on the surface. The masseter is inserted into the 

 lateral surface of the ramus of the mandible, over an area 



