TllK BONES. 



cerebellum; and for tl.is purjww it .-hows four fossa-, distinguished into snperi 

 ccnlirul, and inferior or cereliell ir. These fossa- ar> .-ipant-d liyacnici.il projection 

 whose moat dfvelo|N-d portion forms lln- internal occipital protnln ranee. 



'I'lic union of the occipital with th<- parietal hones con.siitutes the lamMoidal .-iitnn-. 

 At tlio jHiiut whore this bone meets the ptrietal ami the squamous portion of tl.e 

 ti mporul, is fouml. in the infnnt, (lie lateral posterior fontanclla. 



'2. 1'nriital lme#. The parittnls are always isolated in early life. :unl sum- ' 

 consolidated with each otber at the adult ago. They are very large, quadrilateral, ami 

 occupy tbe summit and aides of the cranium. 



The parietal create are absent, but are rep] 



Fig. 35. j n certain individuals, by two faintly-marked 



curved lines situated a little above the inferior 

 border of the bone. Tbe middle portion of the 

 external face is very convex. 



On the internal face there is no parietal pro- 

 tuberance, but in its stead the internal occipital 

 protuberance. It also exhibits ramous channels, 

 which in disposition are analogous to the rilis of 

 a tig-leaf; as well as the parietal fossa which cor- 

 responds to the parietal eminence. 



H. Frontal bone. The frontal bone of Man forms 

 the upper part of the face and the anterior portion 

 of the cranium. Convex from behind forward, then 

 vertical in its upper three-fourths, the bone .sud- 

 denly bends at the orbits, so as to become hori- 

 zontal in its lower fourth. 



The external face offers, above the forehead, two 

 lateral frontal eminences, and above the n< 

 middle frontal boss. To the right and left of the 

 latter are two salient arches, the supraorbital i 

 The internal face entirely belongs to the cranial 

 cavity. It offers on the median line, the saggital 

 groove terminated by a frontal crest; and on each 

 side of this line the frontal fossa), corresponding 

 to the eminences of that name, and orbital bosses 

 1, Frontal bone ; 2, Nasal tuberosity ; to match the orbital roofs. There is no mortice for 

 3, Supra-orbital ridge ; 4, Optic the articulation of the sphenoid bone, 

 foramen ; 5, Sphenoidal fissure ; On the middle portion of the superior frontal 

 6, Spheno-maxillary fissure ; 7, border, in young persons, is tbe anterior angle of 

 Lachrymal fossa ; 8, Opening of the anterior fontanclla. The anterior border ex- 

 the nose divided by the vomer; 9, hibits three superciliary foramina and the orbital 

 luf'ra-orbital foramen ; 10, Malar arches. 



bone; 11, Symphysis of the lower 4. Ethmoid lone. In Man, the external face of 

 jaw; 12, Mental foramen; 13, the lateral masses, formed by a very thin lamina, 

 Ramus of the lower jaw ; 14, Parie- termed the o planum or lamina pupyritw, liel< >nu r > 

 tul bone; 15, Coronal suture; 16, to the internal wall of the orbit. 

 Temporal bone; 17, Squamous 5. Sphenoid bone. This is distinguished, in 

 suture; 18, Upper part of the great Man, into a body and four wings, two large and 

 ala of the sphenoid bone ; 19, Com- two small. 



rnencement of the temporal ridge; The inferior surface of the body offers nothing 

 20, Zygoma of the temporal bone, remarkable, except the presence of a conical pro- 

 concurring to form the temporal longation named the beak (rottrum) of the sphe- 

 arch ; 21, Mastoid process. noid. The external face of the greater wings forms 



part of the temj>oral fossa, as also the external wall 



of the orbit. At the union of the wings with the body are detached two bifid ptery- 

 yoid processes; their internal branch represents the pterygoid bones of animals. There 

 is no subsphenoidal canal. 



The two lesser wings are very thin and triangular, and visible? only on the superior sur- 

 face of the bone; they constitute the processes of Ingra- 



On the internal face of the bone are found : 1, A deep pituitary I'o.-sa, limited l, v 

 four clinoid processes; 2, An optic fossa, shallow, showing very short optic canals trans- 

 formed into foramina; 3, The sphenoidal fissure, which replaces the great snp< r- 

 . pie noidal canal in the Horse; 4, The greatforamen rotnmlum ; :">, The internal face of 

 the wings, much excavated ; t, The foramen ovule, which transmit.- the inferior maxillary 

 nerve; 7, The small foramen rotundum that lodges the spheno-spiiious artery. 



FHO.NT VIEW OF THE HUMAN 

 CRANIUM. 



