66 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



the angle between the external wall and floor is the spheno- 

 maxillary fissure, bounded by the palate, superior maxilla, 

 malar, and sphenoid bones; it leads into the sphenomaxillary 

 fossa at its back part and the zygomatic fossa at its forepart. 

 Passing forward from the margin of this fissure is the com- 

 mencement of the infraorbital canal. On the inner wall in 

 front is the lacrymal groove, leading to the canal of the nasal 

 duct, and farther back, between the frontal and ethmoid, are 

 the anterior and posterior internal orbital or ethmoidal canals. 

 At the junction of the inner and middle thirds of the anterior 

 margin of the roof is the supraorbital foramen or notch. Within 

 the external angular process is the lacrymal fossa, and on the 

 outer wall are the temporal and malar canals. 



The lateral region of the skull presents from behind forward 

 the mastoid portion, the mastoid foramen, the external audi- 

 tory meatus, the glenoid fossa with the condyle of the lower 

 jaw, eminentia articularis, coronoid process, and zygomatic 

 arch. Above this arch is the temporal fossa, and below it, 

 separated by the infratemporal crest, is the zygomatic fossa. 



The temporal fossa, occupied by the temporal muscle, is 

 bounded above by the temporal crest of the frontal and the 

 lower temporal line of the parietal; the latter runs into the 

 supramastoid crest, and that into the zygomatic arch. 



The zygomatic or infratemporal fossa contains a part of the 

 temporal muscle, the external and internal pterygoids, the 

 internal maxillary artery, and the inferior maxillary nerve. 

 Some of its boundaries are indefinite; externally is the ramus 

 of the lower jaw; superiorly the great wing of the sphenoid, 

 showing the foramen ovale and spinosum, also a small part 

 of the squamous portion of the temporal; anteriorly is the 

 lower part of the malar and zygomatic surface of the superior 

 maxilla; the inferior limit is the extremity of the external 

 pterygoid plate and alveolar border of the superior maxilla. 

 The inner wall is formed by the external pterygoid plate; 

 the posterior limit is the eminentia articularis and posterior 

 border of the external pterygoid plate. 



Inferiorly the pterygoid process approaches close to the 

 superior maxilla, but is prevented from meeting by the 

 pyramidal process of the palate. Above they are separated 

 by the pterygomaxittary fissure, leading into the sphenomaxillary 



