130 



SPECIAL ANATOMY OF THE SKELETON 



vomer, bounded above by the body of the sphenoid, below by the horizontal plate 

 of the palate bone, and laterally by the internal pterygoid plate of the sphenoid. 

 Each aperture measures about an inch in the vertical and about half an inch 

 in the transverse direction. At the base of the vomer may be seen the expanded 

 alse of this bone, receiving between them, on each side, the rostrum of the sphe- 

 noid. Near the lateral margins of the vomer, at the root of the pterygoid processes, 

 are the pterygopalatine canals. The pterygoid process, which bounds the posterior 

 nares on each side, presents near its base the pterygoid or Vidian canal, for the 

 Vidian nerve and artery. Each process consists of two plates, which bifurcate at 

 the extremity to receive the tuberosity of the palate bone, and are separated behind 

 by the pterygoid fossa, which lodges the Internal pterygoid muscle. The internal 



FIG. 98. Base of the skull. External surface. 



plate is long and narrow, presenting on the border of its base the scaphoid fossa, 

 for the origin of the Tensor palati muscle, and at its extremity the hamular process, 

 around which the tendon of this muscle turns. The external pterygoid plate is 

 broad, forms the inner boundary of the zygomatic fossa, and affords attachment by 

 its outer surface to the External pterygoid muscle. 



Behind the nasal fossae in the middle line is the basilar surface of the occipital 

 bone, presenting in its centre the pharyngeal spine, for the attachment of the 

 Superior constrictor muscle of the pharynx, with depressions on each side for 

 the insertion of the Rectus capitis anticus major and minor. At the base of the 

 external pterygoid plate is the foramen ovale, for the transmission of the third divi- 

 sion of the trigeminal nerve, the small meningeal artery, and sometimes the small 

 petrosal nerve; behind this, the foramen spinosum, which transmits the middle 



