132 THE FORM OF THE CRANIUM. 



the nose, if the nasal plate of the os palati did not intervene ; 

 this plate forms a partition, which separates the nose from this 

 fissure : and the spheno-palatine foramen, formed principally 

 by it, transmits a nerve and blood-vessels to the nose. 



The fissure is vertical : at the back of the orbit, it unites 

 with the spheno-maxillary fissure of the orbit, which is almost 

 horizontal, and at the place of their junction, the sphenoidal, or 

 upper fissure of the orbit, opens also. 



The foramen rotundum, which transmits the second branch 

 of the fifth pair, or the upper maxillary nerve, is likewise 

 situated near this place ; and when the upper maxillary, the 

 sphenoidal, and the palate bones are in their natural situation, 

 the distribution of the branches of this important nerve can be 

 easily understood : for the same view presents the course of its 

 various branches ; viz. to the nose, by the spheno-palatine fora- 

 men ; to the cavity of the cranium, by the pterygoid foramen ; 

 to the orbit, and the inferior obitary canal, by the spheno-max- 

 illary fissure ; and to the roof of the mouth, by the palato-max- 

 illary canal. 



The Form of the Cranium. 



The form of the cranium is that of an irregular oval. The 

 greatest length of its cavity is between a part of the os frontis 

 above the crista galli, and of the os occipitis above the centre 

 of the crucial ridge. 



The greatest breadth is at about two-thirds of the distance 

 from the first to the last of these positions. This tran verse 

 diameter touches the sides of the cranium near the posterior 

 part of the basis of the petrous portion of the temporal bone. 

 The difl^erence between these longitudinal and transverse 

 diameters varies greatly in different persons, as their craniums 

 approach to the oval or round figures. 



• The greatest depth of the cavity is between the posterior 

 part of the cuneiform process of the occipital bone, and a part 

 of the cranium which is nearly over it about the middle of the 

 sagittal suture. 



The figure of the cranium is somewhat varied in different 



