OPHTH. NERVE 



CAVERNOUS SINUS. 513 



placing the handle of the scalpel in the opening thus made, the 

 extent of the space will be defined. A probe or a blow-pipe will 

 be required, in order that it may be passed into the different 

 sinuses joining the cavernous centre, and these should then be 

 opened up. 



B. The CAVERNOUS SINUS, which has been so named from the Cavernous 

 reticulate structure in its interior, is situate on the side of the body S11 

 of the sphenoid bone. This space, resulting from the separation of 

 the two layers of the dura mater, is of an irregular shape, and 

 extends from the sphenoidal fissure to the tip of the petrous portion 

 of the temporal bone. 



The layer of dura mater bounding the sinus externally is of has nerves 

 some thickness, and contains in its substance the third and fourth wall** 61 

 nerves, with the ophthalmic and superior maxillary trunks of the 

 fifth nerve : these lie in the order given from above downwards. 



The cavity of the sinus is larger behind than before, and is contains 

 traversed by a network of slender fibrous cords. Through the artery^nd 

 space winds the trunk of the internal carotid artery surrounded by sixth nerve : 

 the sympathetic, with the sixth 

 nerve running forwards on the 

 outer side of the vessel ; but all PIT 

 these are bound to the outer wall 

 of the sinus, and separated from INT. C 

 the blood in the space by a thin 

 lining membrane. 



The cavernous sinus receives 

 .1 1,1 i f ,i FIG. 188. TRANSVERSE SECTION OF tributaries 



the ophthalmic veins from the THE CAVERNOUS SlNUS (AFTER and com- 



orbit through the sphenoidal LANGER). 



fissure, and some inferior cerebral 



veins. It communicates with its fellow of the opposite side by 



the hitercavernous sinuses, and with the pterygoid plexus outside 



the skull through the foramen ovale and the foramen lacerum. 



The blood leaves the chamber by the superior and inferior petrosal 



sinuses. 



The INTERCAVERNOUS SINUSES are two vessels which pass trans- intercavem- 

 versely in the sella turcica between the right and left cavernous ^^1- 

 sinuses, being placed one in front of, and the other behind the sinus, 

 pituitary body. To the venous ring thus formed around the 

 pituitary body the name of Circular sinus has been given. 



The SUPERIOR PETROSAL SINUS (fig. 187,/) lies in a groove in the Superior 

 upper edge of the petrous part of the temporal bone, and extends petl 

 between the cavernous and lateral sinuses. Small veins from the 

 cerebellum are received into it. 



The INFERIOR PETROSAL SINUS (fig. 187, k) is larger than the inferior 

 superior, and lies in a groove along the line of junction of the petrosal. 

 petrous part of the temporal with the basilar process of the 

 occipital bone ; it is joined by small veins from the cerebellum, 

 and one from the internal ear. This sinus passes through the 

 anterior compartment of the jugular foramen, and ends in the 

 internal jugular vein. 



D.A. L L 



