Welcome to this presentation on the dural venous sinuses. First, we need to understand some general
considerations as they relate to this subject matter. Here is an example to begin of the superior sagittal sinus.
This is a very prominent sinus. This sinus as well as other sinuses are channels that form within the periosteal
and meningeal layers of the dura mater. Where these sinuses is formed, there is a separation that allows
the venous blood flow to circulate within the cranial cavity. These channels again, such as the superior
sagittal sinus are lined by typical endothelium that you would see in any channel that is conveying
or transmitting blood. The dural venous sinuses drain most structures of the cranial cavity. It’s important
to understand that sinus venous blood drains primarily into the jugular veins. One of the features of
the dural venous sinuses is the presence of arachnoid granulations. These are protrusions of the arachnoid
mater through the dura mater into the venous sinuses. We have one labelled here in the illustration.
This is an arachnoid granulation. It’s projecting into the superior sagittal sinus. Then we see several
others here as well. These are prominent in the lateral lacunae. We’ll see on the next slide where lateral
lacunae are present. The reason we have arachnoid granulations is that they will effect the return of
cerebrospinal fluid to the venous circulation. When we think about the dural venous sinuses, we also need to
consider the arachnoid granulations. In this particular image, we can see several arachnoid granulations.
This area here is showing several prominent arachnoid granulations as well as this area here. These arachnoid
granulations are located within the dura mater in areas called lateral lacunae. Lateral lacunae are areas
where venous blood will be collected. The arachnoid granulations are returning cerebrospinal fluid to this
venous blood. These lateral lacunae do communicate into this very large midline structure that’s referred to as
the superior sagittal sinus. This slide introduces us to the various tributaries of the dural venous sinuses.
So, venous blood from elsewhere will drain into the sinuses. Of course, we also have the arachnoid granulations
contributing as a tributary as well. The first tributary to keep in mind is that the bridging veins, these
may be cerebral or cerebelli in origin. Here, we’re looking at a cerebral bridging vein. This one is emptying
into the superior sagittal sinus. So that’s one type of tributary. A second type of tributary would be
the presence of emissary veins. These are veins that run from the scalp, cross the skull itself, and can empty
blood into dural venous sinus as we see here. Another type of tributary is the presence of diploic veins.
These are running within the skull as we see here and then can empty their venous blood into dural
venous sinus. Meningeal veins are running within the dura mater as we see here. This meningeal vein is
emptying in to this particular dural venous sinus. The last structure to point out on this image is that
arachnoid granulations are also going to be tributaries. We have one arachnoid granulation here but
they are a tributary for cerebrospinal fluid as it’s returning to the venous circulation.