BASE OF THE SKULL. 181 



tremity of the superior curved line of the occiput. It is formed by the palate 

 processes of the superior maxillary and palate bones, the vorner, the pterygoid, 

 under surface of the great wing, spinous process and part of the body of the 

 sphenoid, the under surface of the squamous, mastoid, and petrous portions 

 of the temporal, and the under surface of the occipital bone. The anterior 

 part of the base of the skull is raised above the level of the rest of this surface 

 (when the skull is turned over for the purpose of examination), surrounded by 

 the alveolar process, which is thicker behind than in front, and excavated by 

 sixteen depressions for lodging the teeth of the upper jaw ; the cavities varying 

 in depth and size according to the teeth they contain. Immediately behind 

 the incisor teeth is the anterior palatine fossa. At the bottom of this fossa 

 may usually be seen four apertures, two placed laterally, which open above, 

 one in the floor of each nostril, and transmit the anterior palatine vessels, and 

 two in the median line of the intermaxillary suture, one in front of the other, 

 the anterior transmitting the left, and the posterior (the larger) the right naso- 

 palatine nerve. These two latter canals are sometimes wanting, or they may 

 join to form a single one, or one of them may open into one of the lateral 

 canals above referred to. The palatine vault is concave, uneven, perforated 

 by numerous foramina, marked by depressions for the palatal glands, and 

 crossed by a crucial suture, formed by the junction of the four bones of which 

 it is composed. One or two small foramina, in the alveolar margin behind the 

 incisor teeth, occasionally seen in the adult, almost constant in young subjects, 

 are called the incisive foramina ; they transmit nerves and vessels to the incisor 

 teeth. At each posterior angle of the hard palate is the posterior palatine 

 foramen r for the transmission of the posterior palatine vessels and descending 

 palatine nerve, and running forwards and inwards from it a groove, which 

 lodges the same vessels and nerve. Behind the posterior palatine foramen is the 

 tuberosity of the palate bone, perforated by one or more accessory posterior 

 palatine canals, and marked by the commencement of a ridge, which runs trans- 

 versely inwards, and serves for the attachment of the tendinous expansion of 

 the Tensor Palati muscle. Projecting backwards from the centre of the pos- 

 terior border of the hard palate is the posterior nasal spine, for the attachment 

 of the Azygos Uvulaa. Behind and above the hard palate is the posterior 

 aperture of the nares, divided into two parts by the vomer, bounded above by 

 the body of the sphenoid, below by the horizontal plate of the palate bone, 

 and laterally by the pterygoid processes of the sphenoid. Each aperture 

 measures about an inch in the vertical, and 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 the rostrum of the sphenoid. Near the lateral 

 margins of the vomer, at the root of the pterygoid processes, are the pterygo- 

 palatirie 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 plate is long and narrow, presenting on the outer side 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 occi- 

 pital 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 Eectus Capitis Anticus (major and minor). At the base 

 of the external pterygoid plate is the foramen ovale ; behind this, the foramen 

 spinosum, and the prominent spinous process of the sphenoid, which gives 



