604 



THE BLOOD-VASCULAR AT,s"/7-:JA 



Surgical Anatomy. An arterio-venous communication may he established between tlie 

 cavernous sinus and the carotid artery, as it lies in it, giving rise to a pulsating tumor in the 

 orbit. These communications may be the result of injury, such as a bullet wound, a stab, or a 

 blow or fall sufficiently severe to cause a fracture of the base of the skull in this situation, or 

 they may occur idiopathically from the rupture of an aneurism or a diseased condition of the 

 internal carotid artery. The disease begins with sudden noise and pain in the head, followed by 

 exophthalmos. swelling, and congestion of the lids and conjunctivas, and development of a 

 pulsating tumor at the margin of the orbit, with thrill and the characteristic bruit ; accompany- 

 ing these symptoms there may be impairment of sight, paralysis of the iris and orbital muscles, 

 and pain of varying intensity. In some cases the opposite orbit becomes affected by the pas- 

 sage of the arterial blood into the opposite sinus by means of the circular sinus. Or the arterial 

 blood may find its way through the emissary veins (see page 605) into the pterygoid plexus, and 

 thence into the veins of the face. Pulsating tumors of the orbit may also be due to traumatic; 

 aneurism of one of the orbital arteries, and symptoms resembling those of pulsating tumor may 

 be produced by pressure on the ophthalmic vein, as it enters the sinus, by an aneurism of the 

 internal carotid artery. 



The Ophthalmic Veins are two in number, superior and inferior. 



The superior ophthalmic vein connects the angular vein at the inner angle of 

 the orbit with the cavernous sinus ; it pursues the same course as the ophthalmic 

 artery, and receives tributaries corresponding to the branches derived from that 

 vessel. Forming a short single trunk, it passes through the inner extremity of 

 the sphenoidal fissure, and terminates in the cavernous sinus. 



Opening of mastoid 

 vein. 



* Torcular HerophiK. 

 FIG. 328. The sinuses at thi' base of the skull. 



The inferior ophthalmic vein receives the veins from the floor of the orbit, and 

 either passes out of the orbit through the spheno-maxillary fissure to join the 

 pterygoid plexus of veins, or else, passing backward through the sphenoidal 

 fissure, it enters the cavernous sinus, either by a separate opening, or, more 

 frequently, in common with the superior ophthalmic vein. 



The Circular sinus is formed by two transverse vessels, the anterior and posterior 

 intercavernous sinuses, which connect together the two cavernous sinuses ; the one 

 passing in front and the other behind the pituitary body, and thus forming with the 

 cavernous sinuses a venous circle around that body. The anterior one is usually 

 the larger of the two, and one or other is occasionally found to be absent. 



The Superior petrosal sinus is situated along the superior border of the petrous 

 portion of the temporal bone, in the front part of the attached margin of the 



