_12_, Supraorbital process; _14_, parietal bone; _15_, frontal bone; _16_, squamous temporal bone; _19_, orbit; _20_, malar bone; _21_, lacrimal bone; _22_, nasal bone; _23_, premaxilla; _26_, maxilla; _27_, facial tuberosity; _24_, incisor teeth. (After Ellenberger-Baum, Anat. f. Künstler.) ] [Illustration: FIG. 92.—SKULL AND ATLAS OF OX, VENTRAL VIEW. _13_, Basi-occipital; _13″_, paramastoid or styloid process; _13‴_, occipital condyle; _24′_, incisor teeth; _28_, body of mandible; _31_, condyle of mandible; _32_, ventral tubercle of atlas. (After Ellenberger-Baum, Anat. für Künstler.) ] The =frontal bones= are very extensive, forming about one-half of the entire length of the skull, and all of the roof of the cranium. The posterior borders form with the parietals a large central =frontal eminence= (Torus frontalis), the highest point of the skull. At the junction of the posterior and the lateral borders are the =processus cornu= or “horn-cores,” for the support of the horns. These processes are of elongated conical form, and vary greatly in size, length, curvature, and direction. The external surface is rough and porous, marked by numerous grooves and foramina; in the fresh state they are covered by the matrix of the horns. The base has a constriction, the neck. The interior is excavated to form a number of irregular intercommunicating spaces, divided by bony septa, and communicating with the frontal sinus. In the polled breeds these processes are absent, the skull is narrower in this region, and the frontal eminence more pronounced. The supraorbital process is situated about half-way between the anterior and posterior margins; it is short and joins the frontal process of the malar bone. The supraorbital foramen (often double) is situated about an inch inward from the root of the process; it is the external orifice of the =supraorbital canal= (Canalis supraorbitalis), which passes downward and forward into the orbit. The foramen is in the course of the =supraorbital groove= (Sulcus supraorbitalis), which marks the course of the frontal vein. The anterior ends of the naso-frontal parts form a notch which receives the nasal bones, and sutural or Wormian bones are often found at this junction (naso-frontal suture). The orbital part is extensive; it is perforated behind by the orbital opening of the supraorbital canal, and below by the ethmoidal or internal orbital foramen. It does not articulate with the palatine, from which it is separated by the orbital wing of the sphenoid. The temporal part is also more extensive than in the horse. The frontal sinus is very extensive, being continued into the parietals and occipital, and the horn processes when present.