176 MAXILLARY GROUP. 



7. Maxillary group. Masse ter, ' 

 Temporalis, 

 Buccinator, 



Pterygoideus externus, 

 Pterygoideus interims. 



Dissection. The masseter has been already exposed by the pre- 

 ceding dissection. 



/* /* ^ The MASSETER {pa.aaa.opcU) to chew,) is a short, thick and some- 

 rX^* times quadrilateral muscle, composed of two planes of fibres, super- 



^ A ~~~+ ficial and deep. The superficial layer arises by a strong aponeurosis 

 &-from the tuberosity of the superior maxillary bone, the lower border 

 of the malar bone and zygoma, and passes backwards to be inserted 

 into the ramus and angle of the inferior maxilla. The deep layer 

 arises from the posterior part of the zygoma, and passes forwards, to 

 k e i 1lse ,rfai i n to the upper half of the ramus. This muscle is tendinous 

 and muscular in its structure. 



Relations. By its external surface with the zygomaticus major and 

 risorius Santorini muscle, the parotid gland and Stenon's duct, the 

 transverse facial artery, the pes anserinus and the integument. By 

 its internal surface, with the temporal muscle, the buccinator, from 

 which it is separated by a mass of fat, and with the ramus of the 

 lower jaw, By its posterior border with the parotid gland ; and by 

 the anterior border with the facial artery and vein. 



Dissection. Make an incision along the upper border of the 

 zygoma, for the purpose of separating the temporal fascia from its 

 attachment. Then saw through the zygomatic process of the malar 

 bone, and through the root of the zygoma, near to the meatus audi- 

 torius. Draw down the zygoma, and with it the origin of the mas- 

 seter, and dissect the latter muscle away from the ramus and angle 

 of the inferior maxilla. Now remove the temporal fascia from the 

 rest of its attachment, and the whole of the temporal muscle will be 

 exposed. 



The TEMPORAL is a broad and radiating muscle occupying a consi- 

 derable extent of the side of the head and filling the temporal fossa. 

 *ft is covered in by a very dense fascia (temporal fascia) which is 

 > -^-"attached along the temporal ridge on the side of the skull, extending 

 n~>*^ from the external angular process of the frontal bone to the mastoid 

 *-^ portion of the temporal ; inferiorly, it is connected to the upper border 

 of the zygoma. The muscle arises by tendinous fibres from the whole 

 length of the temporal ridge, and by muscular fibres from the temporal 

 fascia and entire surface of the temporal fossa. Its fibres converge to 

 a strong and narrow tendon, which is inserted into the apex of the 

 coronoid process, and for some way down upon its inner surface. 



Relations. By its external surface with the temporal fascia, which 

 separates it from the attollens and attrahens aurem muscle, the tem- 

 poral vessels and nerves ; and with the zygoma and masseter. By its 

 internal surface with the bones forming the temporal fossa, the exter- 



