SKTJLL OF THE OX AS A WHOLE 



143 



than the rest of the floor. The ethmoidal fossa are smaller, and the hypophyseal 

 fossa or sella turcica is much deeper than in the horse. A deep groove leads from 

 ll-^^iT^ temporal forward over the foramen ovale to the foramen rotundum 

 -cenmcl the sella there is often a distinct prominence (Dorsum sells) . The internal 

 parietal crest is prominent anteriorly, but subsides further back. A faintly marked 

 elevation represents the internal occipital protuberance. The petrous temporal 

 bone projects into the cavity laterally. The ridges and digital impressions are very 

 pronounced. The temporal canal is formed entirely in the temporal bone, and 

 opens mternally at the apex of the petrous, where it is joined by the condyloid 

 canal, ihe foramen lacerum is divided into two parts (For. lacerum orale et ab- 

 orale) . 



The nasal cavity is incompletely divided by the septum, which does not reach 



Dorsal meatus 



Nasal bone 

 i 



Dorsal turhiiKitt 

 Middle meatu. 



LdcriiiHil bo)te 



A'aso-lacrimal canal 

 Maxilla 



Fig. 141. — Cross-section of N.^sal Region op Skull of Ox. Section is Cut between Fourth and Fifth Cheek 



Tooth. 

 1, Cartilage of septum nasi; 2, vomer; 3, ventral meatus; 4. 4', ma.xillary sinuses; 5, .5', palatine sinuses; 6, infra- 

 orbital canal and nerve; 7, horizontal part of palatine bone; 8, communication between maxillary and palatine sinuses. 

 Dotted lines indicate mucous membrane which closes gap in bony floor of nasal cavity. 



the floor posteriorly. The floor is relatively long, and is more concave from side to 

 side than in the horse. In the dry skull it has a large oval opening (Hiatus maxillaris) 

 into the palatine sinus, which is closed during life by mucous membrane. The 

 middle meatus is divided behind into upper and lower branches by the great eth- 

 moturbinate. The choanse or posterior nares are narrow and oblique. 



The frontal sinus is very large. It involves almost all of the frontal bone and 

 a large part of the posterior wall of the cranium. It also extends for a variable dis- 

 tance into the horn processes when these are present. A complete median septum 

 separates the right and left sinuses. The anterior limit is indicated by a transverse 

 plane through the middle of the orbits. It extends laterally to the crest, which 

 limits the temporal fossa above, and into the root of the supraorbital process. At 

 the highest part of the cranial cavity and at the external occipital protuberance 



