BONES OF THE CRANIUM 



135 



They constitute the upper part of the posterior wall, bend sharply forward along 

 tne lateral wall, and enter into the formation of the temporal fossa. The line of 

 inflection is marked by the prominent parietal crest, which is continuous with the 

 temporal crest below and the frontal crest anteriorly. The pari(>tals are excavated 

 to form part of the frontal sinuses in the adult animal. 



Frontal Parietal 

 eminence bone 



Zygomatic mrh 

 Frontal banc 



Supraorbital foramen 

 Supraorbital groove 



Palatine fissure 



Maxilla 

 — Facial tuberosity 



Nasal process of premaxilla 



Palatine process of premaxilla 



Boilij of premaxilla 



Fig. 133. — Skull of Jersey Cow; Dorsal View. 



The condition in the young subject is as follows: The two parietals are united with each other 

 and also with the interparietal and supraoocipital. The resulting mass is somewhat horseshoe- 

 shaped. Its occipital part (Planum occipitale) forms the greater part of the posterior waU of 

 the cranium and bears about its center the tuberosity for the attachment of the hgamentum 

 nuchas. From either side of this a hne curves outward and divides the surface into an upper 

 smooth area and a lower area which is rough for muscular attachment. The upper border joins 

 the frontal bone and concurs in the formation of the frontal eminence. The temporal parts 

 (Plana temporaha) are much smaller and are concave externally; they join the frontal above and 

 the squamous temporal below. A median occipital crest extends ventrally from the external 

 occipital protuberance. 



The frontal bones are very extensive, forming about one-half of the entire 



