CHAPTER VI 

 SKULL AND HYOID 



THE skull can be divided for descriptive purposes into a facial and a cranial part. 

 The cranial bones form the warls of the cavity that contains the brain, and the face 

 bones are situated below the front portion of this " brain-box." 



Looking at the skull from the side, or in sagittal section, we obtain a general idea 



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FIG. 158. The shaded portion of each figure indicates the facial skeleton. In the upper central 

 figure a scheme of the general construction of the skull is seen ; the cranial part has a floor 

 sloping up in front and the face bones are placed below the raised front portion. The 

 whole is supported on the spine by articulation on the cranium. Pterygoid processes 

 hang down from the cranial base behind the face bones ; these are seen in the upper right 

 figure of sagittal section also, but here the lower jaw is in place showing that the face bones 

 extend round on each side of the region of pterygoid plates, while the remainder of the face 

 lies in front of them. Other drawings are from the side, base and front. 



of this relationship (Fig. 158) : the cranial cavity is seen to be deepest behind, with its 

 floor or base sloping upwards and forwards on the whole, and the space below it obtained 

 in this way is occupied by the bones of the face. Looking at it from below, the face 

 bones hide the front part of the cranial region, which is only visible behind them. 

 From the front the cranial portion of the skull is above, the facial part below, and the 

 cavities of the orbits are seen to lie between the two parts : the nasal cavities are placed 

 between the two halves of the face, and the opening of the mouth passes transversely 

 across it, separating the upper from the lower portion or mandible. 



For practical descriptive purposes the division into cranial and facial bones is 

 useful, but, as we will see later, it is not effected on morphological grounds, and, like 



