postorbital process 

 frontal 

 ethmoid 



lacrimal 

 nasal 

 premaxi 



zygomatic arch 



parietal 



squamosal lacrimal foramen 

 infraorbital foramen 

 postparietal 

 supraoccipital 



ethmoid foramen 

 palatine 



prbitosphenoid 



alisphenoid 



dentory 

 mental foramin 



coronoid process 

 articular condyle 

 angular process 



cerotobronchial I (major cornua 

 bosihyol 

 hypohyal D 



ceratohyal 



posterior 



palatine foramen 

 sphenopolatine foramen 



optic foramen 



orbital fissure 

 foramen rotundum 

 foramen ovale 



incisor tooth 



cribriform plate 



frontal 



vomer 



sphenoidal sinus' 



hamulus 

 dorsum sellae 



eustachian canal and petrotympanic fissure 



parietal 



tentorium 



borcuate fossa 



cerebellar fossa 

 endolymphatic 

 foramen 



foramen ovale 

 glenoid fossa 

 postglenoid process- 

 tympanic 

 condylar foramen 

 perilymphatic foramen 

 nternal auditory meatus entotymponic 

 hiatus facialis 



hypoglossal foramen 

 v^ foramen magnum 



.occipital 

 condyle 

 mastoid process 

 stylomastoid foramen 

 tympanic aperture 



postglenoid process 



incisive foramen 



anterior palatine foramen 

 nfraorbital foramen 



vomer 



.orbitosphenoid 



alisphenoid 



zygomatic 



process 



pterygoid canal 



bosisphenoid 

 stylomastoid foramen 

 mastoid process 



exoccipital process 

 jugular foramen 

 hypophyseal fenestra 



Figure 3-2. Head skeleton of young cat. A, lateral view; B, lateral view of skull with zygomatic 

 arch cut away; C, medial view of right half of skull; D, ventral view of skull. 



the rabbit the squamosal has a long, thin posl-tympanic 

 process and an irregular ventral suture line. 



The petrosal is exposed on the outer surface of the cra- 

 nium in a small area between the squamosal and the exoc- 

 cipital. In the cat and dog this part of the bone extends down 

 and forward behind the bulla to end as a rounded process, 

 the mastoid process. The stylomastoid foramen (the outer 

 opening of the facial canal) opens just in front of the 

 process^between this process and the tympanic bone. 



The zygomatic process of the squamosal sutures loosely 

 with the jugal, which forms the ventral margin of the orbit. 

 In the cat and less so in the dog the jugal has an upward 

 projecting postorbital process; anteriorly it tapers to a nar- 

 row upcurved process ending at the lacrimal canal. Ven- 



trally the jugal sutures broadly with the zygomatic process 

 of the maxilla. This suture is lost through fusion in the 

 rabbit. 



In front of the parietals are the paired frontals, w^hich 

 form the major fore part of the roof of the skull. In the cat 

 and dog each frontal has a postorbital process extending out- 

 ward and downward behind the orbit. This process in the cat 

 nearly contacts the short upward process from the jugal. 

 The rabbit lacks this process but has an anterior and poste- 

 rior incisure ("cut out") in the orbit margin. The frontal 

 forms not only the top of the skull between the eyes but also 

 much of the orbit wall. Deep in the orbit it sutures, in the 

 cat and dog, with the alisphenoid ( behind), the orbitosphenoid 

 (next anteriorly), the palatine and then the lacrimal (at the 



38 • OSTEOLOGY AND THE MAMMALIAN HEAD SKELETON 



