QUESTIONS AND ANSWERS 45 



Describe the frontal bone of the ox. 



A very large, flat bone, occupying nearly one-half the anterior 

 surface of the head and forming the front part of the roof of the 

 cranium and part of the face. Quadrilateral in shape, it presents 

 an external and internal face and four borders. The external face, 

 slightly convex, is extended laterally by the processes which form 

 the orbital arches and rest on the malar bone. Its middle region is 

 covered by the skin and constitutes the base of the forehead. In the 

 upper third, the supra-orbital foramen opens into a vasculo- 

 nervous groove which ascends toward the base of the horns, and 

 descends to near the lower border of the bone. The internal face 

 is concave and divided into two unequal parts by a transverse ridge. 

 The superior, the more extensive, is covered with digital impres- 

 sions and belongs to the cranial cavity. The inferior part, articu- 

 lating in the median line with the ethmoid, shows, between the 

 external and internal plates of the bone, the frontal sinuses, two 

 spaces which form part of the roof of the nasal cavities. Projecting 

 from each side of the superior border are the osseous conical cores 

 which support the horns (absent in hornless breeds). These projec- 

 tions are long and curved, very rugged, perforated by foramina and 

 grooved by small vascular channels. The inferior border is deeply 

 notched in its middle to receive the nasal bones. Laterally, the 

 bone articulates with the sphenoid, parietal, lachrymal and malar. 

 The orbital foramen, in the ox, belongs entirely to the frontal bone. 



Describe the superior maxillary bone. 



This bone, the most extensive in the upper jaw, is situated on the 

 side of the face; it is bordered above by the frontal, palatine, 

 zygomatic and lachrymal bones, below by the premaxillary, in front 

 by the nasal, behind and within by that of the opposite side. It is 

 elongated vertically and is irregularly triangular. 



The external face shows a convex surface ending below in the 

 supermaxillary spine ; the infra-orbital foramen. The internal face 

 shows a flat surface which forms the outer wall of the nasal fossa ; 

 the maxillary sinus, the palatine canal ; a ridge for the attachment 

 of the inferior turbinated ; the inferior opening of the lachrymal 

 canal. 



The external border is very thick and hollowed into six large 

 quadrilateral cavities, alveoli, which hold the molar teeth. Above 

 the last alveolus is the alveolar tuberosity, and, below the first, the 

 interdental space. 



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