LATERAL PART OF MIDDLE CRANIAL FOSSA 327 



through the foramen Vesalii, to the pterygoid venous plexus ; 

 and others accompany the internal carotid artery, through 

 the foramen lacerum and the carotid canal, and end in the 

 pharyngeal plexus. 



The cavernous sinus is formed in the same manner as 

 the other venous sinuses. The two layers of the dura mater 

 are separated from each other, and the interval is lined with 

 a delicate membrane. A complicated network of interlacing 

 trabeculae occupies the lumen of the channel, and it is on 

 this account that the term " cavernous " is applied to it. 



Oculomotor nerve 

 Trochlear nerve 



Infundibulum 

 Hypophysis 



Optic nerve 



I Internal carotid artery 



Oculo-motor nerve 



Pterygoid fossa 



Choanai 



FIG. 130. 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. 



This sinus has a special importance on account of its being 

 traversed by the internal carotid artery ; the internal carotid 

 plexus; the oculo- motor, trochlear, and abducent nerves; 

 and the ophthalmic division of the trigeminal nerve. The 

 precise relations which these 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 trigeminal nerve, 

 are closely applied to the lateral wall of the sinus, 

 ii -21 b 



