ZYGOMATIC FOSSA. 



65 



pterygoid plate ; superiorly by the lower part of the great wing of the sphenoid, in which 

 are seen the foramen ovale and foramen spinosum, and by a small part of the squamous 

 of the temporal ; and anteriorly by the zygomatic surface of the superior maxilla, 

 presenting the orifices of the posterior dental canals, together with the lower part of 

 the malar bone. Inferiorly, the external pterygoid plate approaches closely the 

 superior maxillary bone, but the two are usually prevented from meeting by a thin 

 portion of the pyramidal process of the palate bone ; superiorly, they are separated 

 by the pterygo-maxillary fissure, a vertical slit leading above into the spheno- 



Fig. 67. LATERAL VIEW OF THE SKULL REPRESENTED IN FIGURE 65. (Allen Thomson.) J 



1, frontal bone ; 2, parietal bone at the upper temporal line ; x x , coronal suture ; 3, on the 

 occipital bone at the lower end of the lambdoid suture, near its meeting with the occipito-mastoid and 

 parieto-mastoid sutures ; 3', external occipital protuberance ; 4, great wing of sphenoid ; 5, squamous 

 part of temporal ; 6, the same at the root of the zygoma, immediately over the external auditory 

 meatus ; 7, mastoid portion of temporal, at the front of which is the mastoid process ; 8, left condyle of 

 occipital bone ; 9, anterior nasal aperture ; 10, on the lachrymal bone in the inner wall of the orbit ; 

 11, malar bone, near its junction with the zygoma ; 12, superior maxillary bone behind the canine 

 fossa ; 13, ramns of the lower jaw ; 14, body of the lower jaw, near the mental foramen. 



maxillary fossa, and closed internally by the vertical plate of the palate bone. At 

 the upper part of the zygomatic fossa the horizontal spheno-maxillary fissure leads 

 into the orbit. 



The spheno-maxillary fossa is the space which lies in the angle between the 

 pterygo-maxillary and the spheno-maxillary fissures. It is bounded behind by the 

 pterygoid process and the lower part of the anterior surface of the great wing of the 

 sphenoid bone ; in front by the superior maxillary bone ; and internally by the 

 vertical plate of the palate bone with its orbital and sphenoidal processes. Into this 

 narrow space five foramina open, viz., on the posterior wall, the foramen rotundum, 

 the Vidian canal, and, between the sphenoidal process of the palate bone and the root 

 of the internal pterygoid plate, the pterygo-palatine canal ; on the inner wall, the 



VOL. II. Tf 



