CRANIUM 



141 



forward and outward to the supraorbital process. The internal surface is concave 

 and is marked by digital impressions. The lower border projects into the cranial 

 cavity and forms a crest which separates the cerebral and cerebellar compartments 

 laterally. The interior forms part of the frontal sinus in the adult. There is no 

 parieto-temporal canal. 



The frontal bone is long. The frontal surface slopes downward and forward, 

 the inclination varying in different subjects. The anterior part is concave and is 

 marked by the supraorbital foramen and the groove leading forward from the 

 foramen to the nasal bone. The supraorbital 

 canal opens into the orbit at the upper part of 

 the inner wall of the latter. The supraorbital 

 process is short and blunt-pointed, and is not 

 connected with the zygomatic arch. The gap 

 in the orbital margin is closed by the orbital 

 hgament in the fresh state. The orbital part 

 is extensive and forms the greater part of the 

 inner wall of the orbit. Its upper part is per- 

 forated by the orbital orifice of the supraorbital 

 canal, in front of which is the distinct fov(>a 

 trochlearis. The ethmoidal or internal orbital 

 foramen is situated in the lower part near the 

 junction with the orbital wing of the sphenoid. 

 The temporal part is very narrow and is sei:)ar- 

 ated from the orbital plate by a ridge which 

 joins the pterygoid crest below. The interior 

 of the bone is excavated by the frontal sinus in 

 practically its entire extent in the adult. In 

 the young subject the cavity is confined to the 

 anterior part and the rest of the bone is thick. 



The temporal bone has a general resem- 

 blance to that of the ox. The zygomatic pro- 

 cess is short and stout and is bent at a right 

 angle. The upper border of the process is thin ; 

 traced from before backward it curves sharply 

 upward and forms a high prominence in front 

 of the external auditory meatus; beyond this 

 it drops rather abruptly and is then continued 

 upward to the occipital crest. The anterior 

 part of the lower border joins the zygomatic 

 process of the malar, which is deeply notched. 

 The condyle is concave in the transverse direc- 

 tion. The postglenoid process is absent, but 

 the articular surface is bounded behind and in- 

 ternally by a crest. There is no parieto-tem- 

 poral canal. The external auditory canal is very 



long and is directed upward and outward. The bulla ossea is large, compressed 

 laterally, and bears a pointed muscular process in front. A narrow space intervenes 

 between the bulla and the basilar part of the occipital bone, so that the foramen 

 lacerum resembles that of the horse. The small hyoid process is situated in a deep 

 depression in front of the root of the paramastoid process, and the stylo-mastoid 

 foramen is immediately external to it. The petrous part presents no important 

 differential features. The squamous part (including the root of the zygomatic 

 process) contains an air-cavity, which is continuous with the sphenoidal sinus. 



The sphenoid bone is short and resembles that of the ox in general. The body 



Fig. 111. — Basal Surface of Skull of 

 Young Pig, without the Mandible. 

 Sq.o., Supraoccipital; E'.o., exoccipital; 

 B.O., basioccipital; B.s., body of sphenoid; 

 Sq., squamous temporal bone; V, vomer; Mx., 

 maxilla; Pa., horizontal part of palate bone; 

 P.p., palate process of maxilla; Z ., malar bone; 

 J, premaxilla; D.c, canine tooth; Jl-3, in- 

 cisor teeth; O, temporal fossa; 1 , occipital crest; 

 2, for. magnum; 3, occipital condyle; 4, para- 

 mastoid (stjloid) process; 6, bulla ossea; 6, 

 for. lacerum basis cranii; 7, pterygoid process 

 of sphenoid; 8, posterior nares; 9, anterior 

 palatine foramen; /O, palatine cleft. (Struska, 

 Anat. d. Haustiere.) 



