120 SKELETON OF THE OX 



extensive than in the horse. The frontal sinus is very extensive, being continued 

 into the parietals and occipital, and the horn processes when present. 



The squamous and petrous parts of the temporal bone fuse early — in fact, 

 union is nearly complete at birth. The squamous part is relatively small. Its 

 external surface is divided into two parts by the prominent temporal crest, which is 

 continuous with the parietal crest above and turns forward below, ending at a 

 tubercle above the external auditory meatus. The part behind the crest faces 

 backward, and is partly free, partly united with the occipital. The area in front 

 of the crest is concave and enters into the formation of the temporal fossa; it is 

 perforated by foramina which communicate with the parieto-temporal canal. 

 The zygomatic process is much shorter and weaker than in the horse, and articu- 

 lates with the malar only. The condyle is convex in both directions. The post- 

 glenoid process is less prominent, and behind it is the chief external opening of the 

 parieto-temporal canal. The internal surface is almost completely overlapped by 

 the parietal and sphenoid. The petrous part proper is small, but the tympanic 

 part is extensive. The external auditory meatus is smaller than in the horse and is 

 directed outward. From it a plate projects downward and helps to inclose the 

 deep depression in which the hyoid process is placed. Behind this plate is the stylo- 

 mastoid foramen. The muscular process is large and often bifid at its free end. 

 The bulla ossea is large and laterally compressed. It is separated from the occipi- 

 tal bone by a narrow opening which is equivalent to part of the foramen lacerum 

 basis cranii of the horse. The parieto-temporal canal is formed entirely in the 

 temporal bone. The facial canal, on the other hand, is bounded partly by the occi- 

 pital bone. 



Bones of the Face 



The maxilla is shorter but broader and relatively higher than in the horse. 

 Its external surface bears instead of the facial crest a rough facial tuberosity 

 (Tuber malare), placed above the third cheek tooth; a rough curved line often 

 extends from it to the upper part of the malar bone. The infraorbital foramen — 

 often double — is situated above the first cheek tooth. The tuber maxillare is 

 small, laterally compressed, and usually bears a small pointed process (Processus 

 pterygoideus). The zygomatic process is very small. The interalveolar border is 

 concave, and there is no alveolus for a canine tooth. The palatine process is wider, 

 but somewhat shorter than in the horse. It incloses a large air-space, which is 

 continuous behind with a like cavity in the horizontal part of the palate bone, form- 

 ing the palatine sinus. This communicates externally (over the infraorbital canal) 

 with the maxillary sinus; in the macerated skull it communicates with the nasal 

 cavity by a large oval opening, which is closed by mucous membrane in the fresh 

 state. A median septum separates the two palatine sinuses. The alveoli for the 

 cheek teeth increase in size from before backward. The maxillary sinus proper is 

 small and is undivided. The maxillary foramen is a narrow fissure, deeply placed 

 at the inner side of the lacrimal bulla. The maxilla takes no part in the formation 

 of the palatine canal. Sutural (or Wormian) bones may be found at its junction 

 with the lacrimal and malar bones. 



The body of the premaxilla is thin and flattened, and has no alveoli, since 

 the canine and upper incisor teeth are absent. A deep notch takes the place of 

 the foramen incisivum. The nasal process is short, convex externally, and is not 

 closely attached to the nasal bone; the space between the two processes is greater 

 than in the horse. The palatine process is narrow and is grooved on its nasal sur- 

 face for the septal cartilage and the vomer. The palatine cleft is very wide. 



The palatine bone is very extensive. The horizontal part forms one-fourth or 

 more of the hard palate. The anterior palatine foramen opens near the junction 

 with the maxilla, about half an inch from the median palatine suture and crest. 



