THE TEMPORO-MAXILLARY REGION. 403 



the cheeks have been previously distended with air, the Buccinator muscles expel 

 it from between the lips, as in blowing a trumpet. Hence the name (buccina, a 

 trumpet). The Risorius retracts the angles of the mouth, and is therefore regarded 

 as the "smiling" muscle. 



9. Temporo -maxillary Region. 

 * Masseter. J Temporal. 



Masseteric Fascia. Covering the Masseter muscle, and firmly connected with 

 it, is a strong layer of fascia derived from the deep cervical fascia. Above, this 

 fascia is attached to the lower border of the zygoma, and, behind, it covers the 

 parotid gland, constituting the parotid fascia. 



The Masseter is exposed by the removal of this fascia (Fig. 269) ; it is a short, 

 thick muscle, somewhat quadrilateral in form, consisting of two portions, super- 

 ficial and deep. The superficial portion, the larger, arises by a thick, tendinous 

 aponeurosis from the malar process of the superior maxilla, and from the anterior 

 two-thirds of the lower border of the zygomatic arch : its fibres pass downward 

 and backward, to be inserted into the angle and lower half of the outer surface 

 of the ramus of the jaw. The deep portion is much smaller and more muscular 

 in texture ; it arises from the posterior third of the lower border and the whole of 

 the inner surface of the zygomatic arch ; its fibres pass downward and forward, 

 to be inserted into the upper half of the ramus and outer surface of the coronoid 

 process of the jaw. The deep portion of the muscle is partly concealed, in front 

 by the superficial portion ; behind, it is covered by the parotid gland. The fibres 

 of the two portions are united at their insertion. 



Relations. By its superficial surface, with the Zygomatici, the Socia parotidis, 

 and Stenson's duct ; the branches of the facial nerve and the transverse facial 

 vessels, which cross it ; the masseteric fascia; the Risorius, SSjrtgri&i, Platysma 

 myoides, and the integument ; by its deep surface, with the Temporal muscle at 

 its insertion, the ramus of the jaw, and the Buccinator, from which it is separated 

 by a mass of fat. The masseteric nerve and artery enter it on its deep surface. 

 Its posterior margin is overlapped by the parotid gland. Its anterior margin 

 projects over the Buccinator muscle, and the facial vein lies on it below. 



The temporal fascia is seen, at this stage of the dissection covering in the 

 Temporal muscle. It is a strong, fibrous investment, covered, on its outer surface, 

 by the Attrahens and Attollens aurem muscles, the aponeurosis of the Occipito- 

 frontalis. and by part of the Orbicularis palpebrarum. The temporal vessels and 

 the auriculo-temporal nerve cross it from below upward. Above, it is a single 

 layer, attached to the entire extent of the upper temporal ridge ; but below, where 

 it is attached to the zygoma, it consists of two layers, one of which is inserted into 

 the outer, and the other into the inner, border of the zygomatic arch. A small 

 quantity of fat, the orbital branch of the temporal artery, and a filament from the 

 orbital, or temporo-malar, branch of the superior maxillary nerve, are contained 

 between these two layers. It affords attachment by its inner surface to the 

 superficial fibres of the Temporal muscle. , 



Dissection. In order to expose the Temporal muscle, remove the temporal fascia, which 

 may be effected by separating it at its attachment along the upper border of the zygoma, and 

 dissecting it upward from the surface of the muscle. The zygomatic arch should then 

 be divided in front at its junction with the malar bone, and behind near the external auditory 

 meatu.s. and drawn downward with the Masseter, which should be detached from its inser- 

 tion into the ramus and angle of the jaw. The whole extent of the Temporal muscle is then 

 exposed. 



The Temporal (Fig. 273) is a broad, radiating muscle situated at the side of the 

 head and occupying the entire extent of the temporal fossa. It arises from the 

 whole of the temporal fossa except that portion of it that is formed by the malar 

 bone. Its attachment extends from the external angular process of the frontal in 

 front to the mastoid portion of the temporal behind, and from the curved line on 

 the frontal and parietal bones above to the pterygoid ridge on the great wing of 



