THE HEAD. 



59 



replaces the foramen rotnndum and the preat 8i)henoi(iiil fissure, as in tlie Ox. The wings, 

 slightly salient, are articulated by suture with the frontal bone. 



E. Dog, Cat. — The superior sphenoid of the Do<j is very short, and bears, laterally, two 

 wide wings which ascend to the temporal fossa ; they correspond to those of the sphenoid bone 

 in Man. The inferior sphenoid is, on the contrary, very narrow, and its lateral prolongations, 

 or processes of Ingrassias, are reduced to very small proportions. The subsphenoidal or 

 pterygoid process is very short, and tlie canal is single, and communicates with the foramen 

 rotundum. The pituitary fossa is shallow, limited behind and before by the posterior clinoid 

 and anterior clinoid processes, so named because of tlieir being 



compared to tlie four posts of an ancient bed. The supra- 

 splienoidal canals are ouly two in number: one represents 

 the great sphenoidal fissure, the other the round foramen. 

 The carotid notch, joining a similar out- in the temporal 

 bone, forms an opening which may be designated the carotid 

 foramen, because it gives passage to an extremely remark- 

 able loop the internal carotid artery describes after passing 

 through the carotid canal. The oval foremen is the same as 

 in the Ox. 



In the Cat there is the same dispdsition, with the excep- 

 tion of no sphenoidal canal or carotid notch being present 



F. Rabbit. — The body of the sphenoid is short, tri- 

 angular, thick at its upper border, pierced in the middle by 

 an orifice which opens into the pituitary fossa. The wings 

 are very developed ; the eubsphenoidal processes, bifid, are 

 closely embraced by the pterygoids and palatine bones; and 

 the optic fossa is replaced by a large foramen, which com- 

 municates at the same time with the two orbital fo8S£e. 



6. Temporal Bone (Figs. 26, 33). 



The temporal hones enclose the cranial cavity 

 laterally, and articulate with the occipital, parietal, 

 frontal, sphenoidal, and malar bones -, also with 

 the inferior maxilla and the hyoid bone. Each 

 is divided into two pieces, which are never consoli- 

 dated in the horse ; one forms the squamous portion 

 of the temporal hone ,• the other, the petrous portion. 

 They will be described separately. 



Squamous portion. — This is flattened on both 

 sides, oval, and slightly incurvated like a shell, a 

 shape to which it owes its name. It offers for 

 study an external and an internal face, and a circum- 

 ference. 



Faces. — The external face is convex, and marked 

 by some muscular imprints, vascular fissures, and 

 openings which penetrate the parieto-temporal canal. 

 It forms part of the temporal fossa, and gives origin near its middle to the zijgomaiic 

 process — a long eminence which at first runs outwards, and soon curves forwards 

 and downwards to terminate in a thin summit. The base of this eminence forms, 

 in front, a concave surface belonging to the temporal fossa ; behind, it offers the 

 articular surface which corresponds with the maxillary bone. The latter is com- 

 posed of : 1. A condyle transversely elongated, convex above and below, and sHghtly 

 concave from side to side. 2. A glmoid cavity, limited below by the condyle, above 

 by a mammiliform eminence, the supra-condyloid (or anterior mastoid) process,^ 



» In Man this is represented by the inferior or vertical ramus of the upper root of the 

 Bygomatic process. 



14,.— -14 



HEAD OF THE RABBIT (POS- 

 TERIOR face). 



1, Occipital tuberosity; 2, sty- 

 loid process of the occipital 

 bone ; 3, condyle of ditto ; 4, 

 tympanic bulb ; 5, basilar pro- 

 cess of the occipital bone ; 6, 

 body of the sphenoid ; 7, ptery- 

 goid bone ; 8, zygomatic bone ; 

 9, 9, condyles of the temporal 

 bone; 10, palatine bone; 11, 11, 

 superior maxillary bone; 12, 12, 

 premaxilla; 13, orbital pro- 

 cess of the frontal bone ; 14, 14, 

 superior double incisors. 



