EXTERNAL BASE OF THE SKULL. 



67 



spheno-palatine foramen formed by the palate bone and the sphenoid, and opening 

 into the nasal cavity ; and infer iorly, the posterior palatine or palate-maxillary 

 canal, which leads down to the roof of the mouth between the palate and superior 

 maxillary bones. 



The external base of the skull, excluding the lower jaw, is divisible into 

 three parts, anterior, middle, and posterior. 



The anterior division consists of the palate and the alveolar arch. It is 

 traversed longitudinally by a median suture, and transversely by that between the 

 maxillary and palate bones. Anteriorly, in the middle line, is the anterior palatine 



Fig. 70. EXTERNAL BASE OF THE SKULL 

 SHOWN IN FIGURE 65. (Allen Thomson.) J 



1, palate plate of the superior maxil- 

 lary bone ; 2, palate plate of the palate 

 bone ; 3, anterior palatine fossa ; 4, is 

 placed outside the posterior palatine canal, 

 inside the tuberosity of the superior 

 maxilla, and in front of the smaller poste- 

 rior palatine canals ; 5, inner surface of 

 the external pterygoid plate ; 6, is placed 

 within the posterior opening of the right 

 nasal fossa on the internal pterygoid plate; 

 7, vomer ; x , posterior opening of the 

 pterygo-palatine canal in front of the 

 foramen lacerum ; 8, spheno-maxillary 

 fissure leading into the orbit ; 9, foramen 

 spinosum ; 10, foramen ovale ; 11, placed 

 on the apex of the petrous bone, between 

 the foramen lacerum and the inferior 

 opening of the carotid canal ; 12, jugular 

 foramen ; 13, articular eminence of the 

 temporal bone ; 14, external auditory 

 meatus ; 15, glenoid fossa in front of the 

 fissure of Glaser ; 16, tympanic plate or 

 posterior part of the glenoid fossa, close 

 to the styloid process, behind which is 

 seen the stylo-mastoid foramen ; 17, mas- 

 toid process, and to its inside the digas- 

 tric and occipital grooves ; 18, basilar 

 process of the occipital bone, and in front 

 the mark of the still incomplete union with 

 the body of the sphenoid bone ; 19, con- 

 dyle of the occipital bone ; 20, is placed 

 in the foramen magnum, and points to 

 the inner opening of the anterior con- 

 dylar foramen ; 21, posterior condylar 



foramen ; 22, jugular process of the occipital bone ; 23, external occipital crest running down from the 

 protuberance ; 24, superior curved line of the occipital bone ; 25, 26, inferior curved line. 



fossa, with the four foramina opening into it (p. 52) ; posteriorly, on each side, 

 at the base of the alveolar arch, is the opening of the posterior palatine canal, 

 from which the palatine groove, lodging the large palatine nerve and vessels, 

 runs forwards ; and farther back, on the under aspect of the tuberosity of the palate 

 bone, are the apertures of the posterior and external small palatine canals. The palate 

 is surrounded in front and on the sides by the alveolar arch bearing the teeth of the 

 upper jaw. 



The middle division extends back to the front of the foramen magnum. Its 

 central portion has been called the guttural fossa. In the middle line is the basilar 

 process of the occipital bone, and in front of that the body of the sphenoid, covered 

 anteriorly by the alse of the vomer. On each side, the petrous portion of the 

 temporal bone reaches as far forwards as the extremity of the basilar process ; and 



F 2 



