THE HEAD AND NECK 1079 



process of the sphenoid ; then forwards, as far as the anterior clinoid 

 process of the sphenoid ; and, finally, upwards internal to the anterior 

 clinoid process. In the latter situation it pierces the dura mater 

 which forms the roof of the cavernous sinus, and enters upon the 

 cerebral part of its course. 



The vessel is accompanied by the cavernous sympathetic plexus, 

 and the sixth cranial nerve lies in close contact with its outer side, 

 all being invested by the endothelial lining of the sinus. 



Branches. — ^These are as follows : pituitary, to the pituitary body ; 

 ganglioyiic to the Gasserian ganglion ; cavernous, to the wall of 

 the cavernous sinus, and to the third, fourth, fifth, and sixth cranial 

 nerves ; meningeal, to the dura mater of the middle cranial fossa ; 

 and the ophthalmic artery. The latter vessel arises from the 

 cavernous part of the internal carotid on the inner side of the 

 anterior clinoid process, and it enters the orbit, with the optic 



Internal Carotid Artery 



Sixth Nerve 



i ; Sella Turcica 



Third Nerve 

 Fourth Nerve 



Ophthalmic Nerve 

 Superior Maxillary Nerve 





Left Sphenoidal .Air-Sinus 



Fig. 440, — Diagram of the Left Cavernous Venous Sinus and its Outer 

 Wall, showing the Relative Positions of the Contained Struc- 

 tures (Posterior View). 



nerve, through the optic foramen, lying at first beneath the 

 nerve, and then on its outer side. 



Cavernous Sympathetic Plexus. — ^This plexus is situated prin- 

 cipally on the inner and lower aspects of the bend which the 

 cavernous part of the internal carotid artery describes internal to 

 the anterior clinoid process. Its branches are as follows : (i) vas- 

 cular, to the internal carotid artery and its branches ; (2) pituitary, 

 to the pituitary body ; (3) communicating, to the third, fourth, 

 ophthalmic division of the fifth, and sixth cranial nerves ; and 

 (4) the sympathetic root of the ciliary ganglion. The last-named 

 branch enters the orbit through the sphenoidal fissure. 



The pituitary body [hypophysis cerebri) is a small oval mass which is 

 situated in the pituitary fossa, or sella turcica, of the sphenoid bone. 

 It lies under cover of a circular fold of the dura mater, called the 

 diaphragma sellce, in the centre of which is an opening for the passage 

 of the infundibulum. Its long measurement extends transversely, 

 and it consists of two lobes — anterior or buccal, and posterior or cere- 

 bral. The anterior lobe is the larger of the tvvo, and the posterior 



