THE SINUSES OF THE DURA MATER 



659 



The Superior Ophthalmic Vein (v. ophthalmica superior} begins at the inner angle 

 of the orbit in a vein named the nasofrontal which communicates anteriorly with the 

 angular vein; it pursues the same course as the ophthalmic artery, and receives 

 tributaries corresponding to the branches of that vessel. Forming a short single 

 trunk, it passes between the two heads of the Rectus lateralis and through the medial 

 part of the superior orbital fissure, and ends in the cavernous sinus. 



The Inferior Ophthalmic Vein (v. ophthalmica inferior} begins in a venous net-work 

 at the forepart of the floor and medial wall of the orbit; it receives some veins from 

 the Rectus inferior, Obliquus inferior, lacrimal sac and eyelids, runs backward in 

 the lower part of the orbit and divides into two branches. One of these passes 

 through the inferior orbital fissure and joins the pterygoid venous plexus, while 

 the other enters the cranium through the superior orbital fissure and ends in the 

 cavernous sinus, either by a separate opening, or more frequently in common with 

 the superior ophthalmic vein. 



Cavernous 

 sinus 



Inferior 

 ophthalmic 





FIG. 572. Veins of orbit. (Poirier and Charpy.) 



The intercavernous sinuses (sini intercavernosi} (Fig. 570) are two in number, an 

 anterior and a posterior, and connect the two cavernous sinuses across the middle 

 line. The anterior passes in front of the hypophysis cerebri, the posterior behind it, 

 and they form with the cavernous sinuses a venous circle (circular sinus) around the 

 hypophysis. The anterior one is usually the larger of the two, and one or other is 

 occasionally absent. 



The superior petrosal sinus (sinus petrosus superior} (Fig. 570) small and narrow, 

 connects the cavernous with the transverse sinus. It runs lateralward and back- 

 ward, from the posterior end of the cavernous sinus, over the trigeminal nerve, 

 and lies in the attached margin of the tentorium cerebelli and in the superior 

 petrosal sulcus of the temporal bone; it joins the transverse sinus where the latter 

 curves downward on the inner surface of the mastoid part of the temporal. It 

 receives some cerebellar and inferior cerebral veins, and veins from the tympanic 

 cavity. 



The inferior petrosal sinus (sinus petrosus inferior} (Fig. 570) is situated in the 

 inferior petrosal sulcus formed by the junction of the petrous part of the temporal 

 with the basilar part of the occipital. It begins in the postero-inferior part of the 

 cavernous sinus, and, passing through the anterior part of the jugular foramen, 

 ends in the superior bulb of the internal jugular vein. The inferior petrosa! sinus 



