Now, we want to consider the various major dural venous sinuses. The first is one that’s already been
highlighted or emphasized. That is the superior sagittal sinus. We see it running just underneath
the midline and the skull. It has a posterior course and then is ending in the area here of the occiput.
Running within the inferior aspect of the falx cerebri, we have an inferior sagittal sinus which is much
smaller than the superior sagittal sinus. We also have running here, a straight sinus which is coursing posteriorly.
We’ll take a look at this particular sinus again as it relates to another structure. The occipital sinus is
shown here and it has a course among the internal aspect of the occipital bone. We have two
transverse sinuses, a right one and a left one. We see one of those transverse sinuses here. These are very
prominent sinuses. Here is another prominent sinus. This is going to be the sigmoid sinus. These are paired.
These are important in that they are returning the blood to the internal jugular vein. Then more anteriorly,
where the pituitary gland sits in the sella turcica, where we have the internal carotids and some cranial nerves,
we have the cavernous sinus. The next sinus is the superior petrosal sinus. That is visualized right along here.
It runs along the superior aspect of the petrous portion of the temporal bone. Then a collection point, if you will,
of several sinuses is that of the confluence of sinuses. We’ll take a moment here to explain what sinuses
empty into the confluence of sinuses. So here, we’ve isolated, just have one identifier here in the same image.
This is our confluence of sinuses. So what are the dural venous sinuses that empty into this common site?
First is the superior sagittal sinus. We can see its course coming down here posteriorly and inferiorly
to empty its blood into the confluence. Another tributary of the confluence is that it will receive venous
blood from the straight sinus that we see in through here. We can see where it joins and empties into
the confluence. Here, we see the occipital sinus. It too will drain blood into the confluence. So those are
the tributaries that empty into the confluence of sinuses. Now, we want to take a moment to look at the
drainage of venous blood. Again, most of the venous blood is going to drain into the internal jugular veins.
We’re going to begin at the confluence of sinuses and then follow the blood from this particular point.
Blood from the confluence of sinuses will drain laterally into transverse sinuses. Here is the right one.
Then here is the left one. You can see how prominent these transverse sinuses are because of the volume
of blood that they are conveying. From the transverse sinuses, blood will then flow into the sigmoid sinuses.
If we take a look, here is the right transverse sinus emptying into the sigmoid sinus. Then we also have
that same travel here or conveyance on the left side. So here’s the left sigmoid sinus. Then the sigmoid
sinuses will drain into the very initial segment of the internal jugular vein. That is referred to as the bulb
of the internal jugular vein. Then the internal jugular vein will exit the skull through the jugular foramen.