LATERAL PART OF MIDDLE CRANIAL FOSSA 331 



tions from the carotid plexus and from the ophthalmic 

 nerve ; and they all enter the orbit by passing through 

 the superior orbital fissure. Before doing so, the oculo- 

 motor nerve divides into an upper and a lower division. 

 As they pass through the superior orbital fissure the various 



Infundibulum 



Abducent nerve 



Trigeminal nerve 

 Trochlear nerve 



Glosso-pharyn- 

 geal nerve 



Accessory nerve 



Section through 



the medulla 



oblongata 



Transverse sinus 



Superior sagittal sinus 



tic nerve 

 Internal carotid 

 artery 



Posterior 

 communicating 



Oculo-motor nerv 



Posterior cerebr: 

 Superior 

 cerebellar 

 Tentorium 



Basilar 

 artery 



Vertebral 

 artery 



Superior petro 

 sinus 



Transverse sinus 



Occipital sinus 



Straight sinus divided 



FIG. 132. Floor of the Cranium after the removal of the Brain and the 

 Tentorium Cerebelli. The blood-vessels forming the circulus arteriosus 

 have been left in place. 



nerves undergo a change in their relative positions. This, 

 however, will be studied in the dissection of the orbit. 



Arteria Carotis Interna. The intracranial portion of the 

 internal carotid artery may now be examined. It lies upon 

 the lateral aspect of the body of the sphenoid, and, for the 

 greater part of its course, it traverses the cavernous sinus. It 

 emerges from the carotid canal into the foramen lacerum 

 at the apex of the petrous bone ; then it passes through the 

 upper part of the foramen lacerum, pierces the outer layer 



