1478 A MANUAL OF ANATOMY 



or inferior occipital sinuses remain separate, and then each opens 

 into the corresponding lateral sinus. The occipital sinus receives 

 tributaries from the falx cerebelli and the inferior surface of the 

 cerebellum, and it establishes a communication between the com- 

 mencement and termination of the lateral sinuses. 



The cavernous sinuses are two in number — right and left — and 

 are so named because the interior of each is broken up by fibrous 

 filaments, which import to it a reticular appearance. Each sinus 

 is situated on the side of the body of the sphenoid bone, and extends 

 from the inner extremity of the sphenoidal fissure to the apex of 

 the petrous part of the temporal bone. Anteriorly it receives the 

 ophthalmic vein, or veins, from the orbit, and posteriorly it ter- 

 minates by dividing into the superior and inferior petrosal sinuses. 

 In addition to the ophthalmic vein, or veins, the cavernous sinus 

 receives the spheno-parietal sinus and some of the inferior cerebral 

 veins. It communicates with the angular vein of the face through 

 the superior ophthalmic vein ; with its fellow of the opposite side 

 through the circular sinus ; with the lateral sinus by the superior 

 petrosal sinus ; with the internal jugular vein by the inferior petrosal 

 sinus ; with the pterygoid plexus through the inferior ophthalmic 

 vein, and by an emissary vein which passes through the foramen 

 ovale, or through the foramen Vesalii ; and with the pharyngeal 

 p'exus by an emissary vein which passes through the foramen 

 lacerum medium. The internal carotid artery, with the cavernous 

 sympathetic plexus, lies in contact with the inner wall of the sinus, 

 and the sixth cranial nerve is close to the outer side of the artery. 

 In connection with the outer wall of the sinus there are the third, 

 fourth, and ophthalmic and superior maxillary divisions of the 

 fifth, cranial nerves. 



The spheno-parietal sinuses are two in number — right and left. 

 Each is of small size, and is situated on the inferior surface of the 

 small wing of the sphenoid bone. It generally commences in 

 connection with the anterior temporal diploic vein, and termi- 

 nates in the anterior part of the cavernous sinus. 



The circular sinus surrounds the pituitary body in the pituitary 

 fossa. It is composed of two transverse sinuses — anterior inter- 

 cavernous and posterior intercavernous — which lie in front of and 

 behind the pituitary body, and establish communications between 

 the cavernous sinuses. 



The superior petrosal sinus is situated along the superior border 

 of the petrous part of the temporal bone, and lies within the attached 

 margin of the tentorium cerebelli. It commences at the back part 

 of the cavernous sinus, and, having passed outwards and backwards, 

 it opens into the lateral sinus as that is about to enter the sigmoid 

 groove of the pars mastoidea. It receives tributaries from the 

 cerebellum and tympanum. 



The inferior petrosal sinus occupies the groove at the junction of 

 the basilar process of th(; occipital bone with the petrous part of 

 the temporal bone. It commences at the back part of the cavernous 

 sinus, and, passing backwards and slightly outwards, it leaves the 



