HEAD AND NECK 



the internal carotid plexus; the oculo-motor, trochlear, and 

 abducent nerves; and the ophthalmic division of the tri- 

 geminal nerve. The precise relations which those structures 

 bear to its walls will be described later ; in the meantime it is 

 necessary only to note that two, viz., the internal carotid 

 artery and the abducent nerve, lie more distinctly within the 

 interval between the two layers of the dura mater than the 

 others, but that they are shut out from the blood channel by 

 the delicate lining membrane of the sinus. The oculo-motor 

 and trochlear nerves, and the ophthalmic division of the 



Oculo-motor nerves 

 Trochlear nerve^^ 



Ophthalmic 

 nerve 

 Abducens 

 nerve 



Infundibulum 

 Hypophysis 



\ 



Optic nerve 



Internal carotid artery 



Oculo-motor nerve 



Pterygoid fossa 



Choana 



Vomer 



FIG. 86. Frontal section through the Cavernous Sinus to show the position 

 of the Nerves in its wall. Note the branch given to the hypophysis 

 (O.T. pituitary body) by the internal carotid artery. 



trigeminal nerve, are closely applied to the lateral wall of 

 the sinus (Figs. 85, 86, 87, 92). 



Nervus Trigeminus. The two roots of the trigeminal nerve 

 have already been seen passing between the two layers of 

 the dura mater, at the apex of the petrous portion of the 

 temporal bone, under the anterior margin of the tentorium. 

 Now that the dura mater has been raised from the lateral 

 part of the middle cranial fossa, the further relations of those 

 nerve-roots within the cranium may be studied. It will be 

 noticed that the loosely connected and parallel funiculi of 

 the portio major, or sensory root, at once begin to divide 

 and join with each other so as to form a dense plexiform 



