BASE OF THE SKULL. 



59 



Fig. 25.* 



The external surface of the base of the skull is extremely irregu- 

 lar. From before backwards it is formed by the palate processes 

 of the superior maxillary and pa- 

 late bones ; the vomer ; the ptery- 

 goid, spinous processes, and part 

 of the body of the sphenoid ; under 

 surface of the squamous portion, 

 and mastoid portion of the tem- 

 porals ; and by the occipital bone. 

 The palate processes of the supe- 

 rior maxillary and palate bones 

 constitute the hard palate, which 

 is raised above the level of the 

 rest of the base, and is surrounded 

 by the alveolar processes contain- 

 ing the teeth of the upper jaw. At 

 the anterior extremity of the hard 

 palate, and directly behind the 

 front incisor teeth, is the incisive 

 foramen , the term ination of the naso- 

 palatine canal, which contains the 

 naso-palatine ganglion, and trans- 

 mits the anterior palatine nerves. At 

 the posterior angles of the palate are the posterior palatine foramina, 

 for the posterior palatine nerves and arteries. Passing inwards from 

 these foramina are the transverse ridges to which are attached the ex- 

 pansions of the tensor palati muscles, and at the middle line of the 

 posterior border the palate spine which gives origin to the azygos 

 uvulae. The hard palate is marked by a crucial suture, which distin- 

 guishes the four processes of which it is composed. Behind, and above 

 the hard palate, are the posterior nares, separated by the vomer, and 

 bounded on each side by the pterygoid processes. At the base of the 

 vomer, and partly formed by its expansion, are the pterygo-palatine 

 canals. The internal pterygoid plate is long and narrow, terminated 

 at its apex by the hamular process, and at its base by the scaphoid 

 fossa. The external plate is broad, and the space between the two is 

 the pterygoid fossa, which contains part of the internal pterygoid 

 muscle and the tensor palati. Externally to the external pterygoid 



* The external or basilar surface of the base of the skull. 1, 1. The hard palate. 

 The figures are placed upon the palate processes of the superior maxillary bones. 2. 

 The incisive, or anterior palatine foramen. 3. The palate process of the palate bdne. 

 The large opening near the figure is the posterior palatine foramen. 4. The palate 

 spine; the curved line upon which the number rests, is the transverse ridge. 5. The 

 vomer, dividing the openings of the posterior nares. 6. The internal pterygoid plate. 

 7. The scaphoid fossa. 8. The external pterygoid plate. The interval between 6 and 8, 

 (left side of the figure,) is the pterygoid fossa. 9. The zygomatic fossa. 10. The 

 basilar process of the occipital bone. 11. The foramen magnum. 12. The foramen 

 ovale. 13. The foramen spinosum. 14. The glenoid fossa. 15. The meatus audi- 

 torius externus. 16. The foramen lacerum basis cranii. 17. The carotid foramen of 

 the left side. 18. The foramen lacerum posterius, or jugular foramen. 19. The 

 styloid process. 20. The stylo-mastoid foramen. 21. The mastoid process. 22. One 

 of the condyles of the occipital bone. 23. The posterior condyloid foramen. 



