THE HEAD. 



91 



Fig. 55. 



4. Ethmoid hone.— In Man, the external fa^e of the lateral masses— formed by a very 

 thin lamina, termed the os planum or lamina pap2/r«e«— belongs to the internal wall of the orbit. 



5. Sphenoid bone.— TLiis is distinguished, in Man, into a body and four wings- two large 

 and twfi small. 



Tlie inferior surface of the body oflfers nothing remarkable, except the presence of a conical 

 prolongation named the beak (rostrum) of the .sphenoid. The external face of the greater 

 wings forms part of the temporal fowsa, as also the external wall of the orbit. At the union 

 of the wing.s with the body, are detached two bifid 

 pterygoid proce.-^ses ; their internal branch represents 

 the pterygoid bones of animals. There is no sub- 

 sphenoidal canal. 



Tlie two lesser wings are very thin and triangular, 

 and visible only on the superior surface of the bone ; 

 they constitute the processes of Ingrassias. 



On the internal face of the bone are found : (1) 

 a deep pituitary fossa, limited by four cUnoid pro- 

 cesses; (2) an optic fossa, shallow, showing very 

 short optic canals transformed into foramina ; (3) the 

 sphenoidal fissure, which replaces the great super- 

 spheiioidal canal in the Horse; (4) the great foramen 

 rotundum; (5) the internal face of the wings, much 

 excavated ; (6) the foramen ovale, which transmits 

 the inferior maxillary nerve ; (7) the small foramen 

 rotundum that lodges the spheno-spinous artery. 



6. Temporal hone. — In the squamous portion of 

 the temporal bone of Man, the zygomatic process only 

 rests on the malar bone, as in Ruminants. The glenoid 

 cavity is concave in every sense, ami divided into two 

 parts by an opening named t\\e fi'<sura Glaneri ; the 

 anterior portion only is articular — the posterior, lying 

 against the external auditory canal, does not belong 

 to the articulation ; it corresponds to the supra-con- 

 dyloid eminence of the Horse. The tuberous portion 

 is consolidated with the squamous. It is divided into 

 a mastoid and a pyramidal portion ; the latter com- 

 prises, in its turn, the petrous an^l tympanic portions. 

 The mastoid portions correspond to the mastoid pro- 

 cess, mastoid protuberance, and superior border of the 

 petrous bone in the Horse. It presents a rugged 

 mast(;id process. Above this is the mastoid canal ; 

 and aliove and behind it, tlie digastric groove — tlie 

 pyramid forming a considerable projection in the 

 interior of the cranium. The styloid process or bone 

 is altogether separate from the other pieces of the 

 hyoid, and in the adult is consolidated with the tem- 

 poral bone. 



7. Supermaxilla. — In Man the premaxilla is no 

 longer found independent, the centre which forms it 

 coalescing with the supermaxillary bone. 



The supermaxilla of man concurs, for the greater 

 part of its extent, to form the floor of the orbit ; it 



is also divided into three faces : an external or facial, a superior or orbital, and an internal 

 or naso-palatine. The external face presents, from before to behind: (1) a small fossa, into 

 which is inserted the niyrtiform muscle; (2) the infra-orbital, or canine fossa, showing the 

 inferior orifice of the infra-orbital canal; (3) a crest corresponding to the maxillary spine of 

 Solipeds : (4) the alveolar tuberosity. This face carries, in front, a prolongation that forms the 

 ascending process, also named, because of its relation, the tronto-nasal process. The superior 

 or orbital face oflfers a fissure which precedes the infra-orbital canal, and, outwards, the malar 

 process. The internal face is divided by the palatine process. It shows, in front, the half of 

 the anterior nasal spine and a groove which participates in the formation of the incisive canal. 



8. Palatine fcojie.- The palatine bone of Man isformedof two osseous laminae— one horizontal, 

 the other vertical— which are joined at a right angle. The first part presents : one-half of the 



EXTERNAL OR BASILAR SURFACE OF 

 THE BASE OF THE HUMAN SKULL. 



, ], The bony palate; 2, incisive, or 

 anterior palatine foi-amea; 3, pala- 

 tine process of p date bone, with the 

 posterior palatine foramen ; 4, palate 

 spine with transverse ridge ; 5, vomer ; 

 6, internal pterygoid palate ; 7, sca- 

 phoid fossa; 8, external pterygoid 

 plate, with fossa ; 9, zygomatic fossa ; 



10, basilar process of occipital bone ; 



11, foramen magnum; 14, glenoid 

 fossa; 15, meatus auditorius exter- 

 nus ; 16, foramen lacerum anterius ; 

 17, carotid foramen of left siile; 18, 

 foramen lacerum posterius, or jugular 

 foramen; 19, styloid process; 20, 

 stylo-mastoid foramen, with jugular 

 tubercle and digastric fossa ; 21, mas- 

 toid process ; 22, occipital bone ; 23, 

 posterior condyloid fossa. 



