Table of ContentsTransverse and Sigmoid SinusesSuperior Petrosal SinusInferior Petrosal SinusTwo or three meningeal sinuses may join to form a vestibule just before reaching the superior sagittal sinus. There is a tendency for veins draining the lateral surface of the anterior frontal and posterior parietal regions to join the meningeal sinus in the dura mater lateral to the superior sagittal sinus. The veins of the posterior frontal and parietal region most often dip below the venous lacunae and pass directly to the superior sagittal sinus. Veins from the medial surface of the hemisphere enter the lower border of the sinus or turn laterally on the upper border of the hemisphere to join the veins on the lateral surface before entering the sinus. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essayThe superior sagittal sinus segment in the frontal region above the genu of the corpus callosum receives fewer bridging veins than any other area except the 4 to 6 cm near the torcular herophilus, where the bridging veins rarely enter the superior sagittal sinus. The inferior sagittal sinus (Fig. 2) extends into the lower border of the falx (16). It originates above the anterior part of the corpus callosum and enlarges as it extends posteriorly to join the right sinus. It results from the union of the veins of the adjacent part of the falx, the corpus callosum and the cingulate gyrus. The junction of the veins of the cingulate gyrus and corpus callosum with the sinus often forms an acute hook-shaped curvature, with the apex directed anteriorly. The largest tributaries of the inferior sagittal sinus are the anterior pericallosal veins. The superior sagittal sinus can communicate via a false venous canal with the inferior sagittal sinus. This connection may rarely be so great that the superior sagittal sinus flows primarily into the lower, straight sagittal sinuses. Right sinusThe right sinus (Fig. 5) arises behind the selenium of the corpus callosum, at the union of the inferior sagittal sinus and the great vein. .(16) It continues back and down to the junction of the tent and the scythe. It can flow into either transverse sinus, but more often it flows primarily into the left transverse sinus. Transverse and sigmoid sinuses The right and left transverse sinuses arise from the torcular. herophilic and extend laterally from the internal occipital protuberance in a shallow furrow between the tentorium attachments to the inner surface of the occipital bone. (16) The transverse sinus exits the tentorial attachments to become the sigmoid sinus at the site just behind the petrous crest, where the transverse and superior petrosal sinuses meet. Although the superior sagittal sinus may drain equally to the left and right transverse sinuses or primarily or entirely to either side, it is the right transverse sinus that is generally larger and receives the majority of drainage from the superior sagittal sinus. The left transverse sinus is generally smaller and primarily receives drainage from the right sinus. Thus, the right transverse sinus, the right sigmoid sinus and the right jugular vein contain blood coming from the superficial parts of the brain, and the left transverse sinus, the left sigmoid sinus and the left internal jugular vein contain blood coming mainly from the deep parts of the brain. drained by the internal, basal and great cerebral veins. The difference in symptoms caused by blockage of venous drainage on one side or the other and the differences in the sign ofQueckenstedt with compression of the jugular veins on the left or right side were This is explained by the differences in drainage on each side. Cortical veins from the lateral surface of the temporal lobe may flow into the transverse sinus, but before entering it they usually pass medially under the hemisphere to join a short sinus in the tentorium, which extends into the tent for about 1 cm before draining into the terminal part of the transverse sinus. Cortical veins from the basal surface of the temporal and occipital lobes generally join the lateral tentorial sinus. The vein of Labbé usually terminates in the transverse sinus, but may curve around the lower border of the hemisphere to join the lateral tentorial sinus. The transverse sinus can communicate through the emissary veins of the occipital bone with the extracranial veins. The occipital sinus (fig 7) is the smallest of the cranial sinuses. It is located in the attached edge of the falx cerebellum, and is usually single, but sometimes there are two. It begins around the edge of the foramen magnum with several small venous canals, one of which joins the terminal part of the transverse sinus; it communicates with the posterior internal vertebral venous plexuses and ends at the confluence of the sinuses. (21) Each half of the tentorium has two constant but rarely symmetrical venous channels, the medial and lateral tentorial sinuses. (16) The medial tentorial sinuses are formed by the convergence of veins from the upper surface of the cerebellum. The medial tentorial sinuses extend medially to empty into the right sinus or at the junction of the straight and transverse sinuses. The lateral tentorial sinuses are formed by the convergence of veins from the basal and lateral surfaces of the temporal and occipital lobes. The lateral tentorial sinuses arise in the lateral part of the tentorium and extend laterally to drain into the terminal part of the transverse sinus. The paired cavernous sinuses are located on either side of the sella turcica and are connected across the midline by the anterior and posterior sinuses. intercavernous sinuses, which extend to the junction of the venous diaphragm with the dura mater lining the saddle. (16) Anteriorly, each cavernous sinus communicates with the sphenoparietal sinus and the ophthalmic veins. Its middle part communicates by a lateral extension on the internal surface of the greater sphenoid wing with the pterygoid plexus via small veins which cross the foramens spinosum and ovale. .Posteriorly, the cavernous sinus opens directly into the basilar sinus, which rests on the clivus. It communicates through the superior petrosal sinus with the junction of the transverse and sigmoid sinuses and through the inferior petrosal sinus with the sigmoid sinus. Superior petrosal sinusThe superior petrosal sinus (fig 12) extends into the tentorium attachment to the petrous crest (16).Its medial end connects to the posterior end of the cavernous sinus. ü its lateral end joins the junction of the transverse and sigmoid sinuses. The bridging veins that join it usually originate from the cerebellum and brainstem, not the cerebrum. The sinus may pass over, under, or around the posterior root of the trigeminal nerve. The superficial sylvian veins may drain into an infrequent tributary of the superior petrosal sinus called the sphenopetrosal sinus. Inferior petrosal sinusThe inferior petrosal sinuses (fig 12) are small sinuses located on the lower border of the petrous portion of the temporal bone on each side (16).Each inferior petrosal sinus drains the cavernous sinus into the internal jugular vein. The inferior petrous sinus is located in the inferior petrosal groove, formed by the junction of the petrous part of the temporal bone with the basilar part of the occipital bone. begins in the posteroinferior part of the cavernous sinus and, in.