82 THE BONES. 



are the condyloid fossae, with their condyloid foramen., and the styloid processes of 

 the occipital hone or Jugular eminences. 



2. Suhsphenoidal region. — This region is notably constricted in its middle 

 part, where it has for base the body of the posterior sphenoid bone ; it is enlarged 

 above by the temporal articular surfaces. It is limited by the inferior border 

 of the foramen lacerum, on which are three notches transformed into foramina 

 by the tissue that partitions the foramen lacerum basis cranii in the fresh 

 state. These openings are, passing from within to without, the carotid or cavernous 

 foramen, the foramen ovcde or foramen rotundum ; they are all preceded by a 

 groove on the surface of the bone. On each side of the body of the sphenoid is 

 the narrow Vidian fissure, prolonged by the Vidian canal, and margined outwardly 

 by the origin of the suhsphenoidcd process. Laterally, is the suhsphenoidal canal 

 for the passage of the internal maxillary artery, which is continued forward 

 by two branches, one of which opens into the orbital hiatus, the other into the 

 temporal fossa. 



3. Spheno-pcdatine region. — This extends from the superior sphenoid to the 

 palatine arch. In the median plane it shows a vast elliptical opening — the 

 gutturcd opening of the nascd cavities, divided at the bottom into two portions by 

 the vomer, and bordered laterally by two elevated crests (pterygo-pcdatines) 

 resulting from the junction of the pterygoids with the palatine crests ; and 

 limited in front by the posterior border of the palatine bones, which is raised in 

 its middle by a blunt point directed backwards — the nasal spine. Beyond the 

 pterygo-palatine orests is a slightly depressed surface, on which run the branches 

 of the internal maxillary artery and the superior maxillary nerve. This surface 

 extends, above, to the orhital or sphenoidctl hiatus, below to the maxillary hiatus. 

 In the maxillary hiatus are : the upper opening of the superior dental canal, the 

 palatine caned, and the nasal foramen. In passing from the maxillary hiatus on 

 the margin of the guttural opening of the nasal cavities, we meet with the 

 staphyline fissure, which is limited above by the alveolar tuberosity. 



4. Pcdatine region. — .This is a wide elongated surface, limited laterally by the 

 molar teeth and interdental spaces, and in front by the incisors. It shows : in 

 the middle, the pcdcdine and superior maxillary suture, which terminates at the 

 incisive canal ; on the sides and above, the inferior opening of the pcdatine grooves^ 

 prolonged by the pcdatine fissures ; in front, the incisive slits. 



C. Lateral Face. — This is a pair face, and comprises three regions (Fig. 51) : 



1. Maxillary region. — This is very extensive. Its shape is triangular, base 

 superior — the supermaxilla being joined to the premaxilla. Proceeding backward, 

 there are observed : a fossa, in which opens the infra^rhital foramen ; the lower 

 orifice of the superior dental canal, pierced above the third molar tooth ; the 

 malar or zygomatic spine — a long vertical crest for the insertion of the masseter 

 muscle, commencing above the fourth molar teeth, and continuing upwards with 

 the malar bone and zygomatic process. Lastly, the maxillary region is limited, 

 above, by the orbit and the maxillary tuherosity. 



2. Orhital region. — This includes the orbit or orbital cavity, for the reception 

 of the essential and some of the accessory organs of vision. In Man and the 

 Quadrumana this cavity has complete bony walls, but in the domestic animals it 

 always largely communicates with the temporal fossa, and it is not always 

 even circumscribed at its opening by a soHd ring. A fibrous lining {ocular sheath) 

 converts it into a distinct cavity. 



In the Horse, the outline of the orbit is constituted : below, by the lachrymal 



