THE CAT. 



[CHAP. in. 



form plate), and in part by the nasal cavity (in front of the 

 cribriform plate). 



The nasal fossce extend backwards, above the palate, from the 

 anterior to the posterior nares, and are enclosed between the pre- 

 inaxillaD, maxilla, and palatines, being separated from each other 

 by the median ethmoid and vomer, and, in front of these, by a 

 median cartilage of the nose called " septal." The lateral ethmoid 

 projects forwards into each fossa from the cribriform plate (cp). 



The roof of the nasal cavity slopes downwards both anteriorly 



el- 



Fig. 50. LONGITUDINAL VERTICAL SECTION OF FACE MADE A LITTLE FURTHER OFF 



THAN THE MIDDLE LINE. 



cp. Cribriform plate. 



et. Lateral ethmoid or ethmo-turbinal. 



Js. Frontal sinus. 



mt. Maxillo-turbiual. 



in. Maxilla. 



p. Palatine. 

 pm. Pre-maxilla. 

 ps. Pre-sphenoid. 

 pt. Pterygoid. 



and posteriorly. Its floor is formed by the palatal plates of the 

 maxillae and palatines, and is pierced, towards its anterior end, by 

 the anterior palatine foramina. 



The spheno-palatine foramen opens into the nasal cavity on each 

 side towards the hinder end very near its floor. 



The bones of the cranial vault are densest at the surface, beneath 

 which is a coarser, spongy bone-tissue termed " dipfoc." Here and 

 there are much larger cavities, which are filled with air, and are 

 termed sinuses. Of such there are two sets. 



The first of these, the frontal sinuses, are in the substance of the 

 frontals (/$), and they communicate with the nasal fossaB. The 

 other set, the sphenoidal sinuses, are situated in the pre-sphenoid, 

 and are smaller than the frontal sinuses (Fig. 49, ps). 



40. Besides the LIGAMENTS of the skull already noticed those 

 connecting it with the vertebral column other ligaments connect 

 the mandible with the cranium. 



These maybe described as the " capsular " and " stylo-maxillary " 

 ligaments. 



The apposed surfaces of the mandibular condyle and glenoid 

 cavity are, in the fresh condition, each coated with cartilage, and 



