Dural Venous Sinuses (Location + Visual Scheme) | Anatomy

Let's go ahead and talk about the 

anatomy of the dural venous sinuses and we're going to do that by first going 

through the location of the dural sinuses basically where they are in comparison to the 

meninges and then we're going to visualize the dural venous sinuses schematically so that 

it's easier to remember the dural sinuses and then in the next video we're going 

to go through the cerebral veins and the emissary veins and the diploic veins and 

then the cerebral circulation in general. All right, so the veins of the systemic 

circulation consist of four kind of systems. You have the veins of the heart, then you have the 

veins of the inferior vena cava, and the veins of the superior vena cava, and then you have the 

portal system. So the superior venous sinuses we're going to go through drain into the superior 

vena cava so we can start by zooming in on this figure and then take a small section of the skull 

in order to see all the layers so these are all the layers from the skin down to the brain tissue. 

So first we have the skin all the dermal layers then underneath that we have the skull and then 

the meninges and then there's the cerebral tissue. So the meninges are what we're essentially going 

to focus on right now. So the meninges consists of three layers. You have the pia mater 

which is the thinnest most delicate layer that lies just on top of the 

surface of the brain tissue. Then superficially to that you will find the 

arachnoid mater, which is slightly thicker than the pia mater, and underneath the arachnoid 

mater you will find the subarachnoid space which contains cerebrospinal fluid and you will 

notice that there are these arachnoid granulations that take the cerebrospinal fluid and then just 

pumps them into the venous sinuses so that they can get back into the circulation to complete 

the circulation of the cerebrospinal fluid. Then superficial to the arachnoid mater 

you will find the thickest meninges called the dura mater and notice that the 

dura mater inside the cranium consists of two layers there's first the periosteal 

layer which lies very close to the skull and then there's the meningeal layer which 

lies very close to the arachnoid mater and when you look at the spinal cord you'll notice 

that dura mater only consists of one layer which is the meningeal layer because the 

periosteal layer stops at the foramen magnum. Notice that the periosteal layer and 

the meningeal layer are bound together and only separate when they form the dural 

venous sinuses and the dural septae. So if I would ask you between which layers are the 

dural venous sinuses located inside the head, they are located between the periosteal 

and the meningeal layer of the dura mater. Awesome now finally let's go ahead and 

go through the dural venous sinuses. So what we're going to do is that we're going to 

go through all the dural venous sinuses one by one and we will use this table to help us do that. All right, so first thing is that 

I've divided the dural venous sinuses into the ones that are located in the 

midline, the ones that are located laterally, the ones that are located 

posteriorly and anteriorly, and you will notice that when you're studying 

the dural venous sinuses that there are different ways to categorize the different dural 

venous sinuses. You can also categorize them as paired and unpaired for example, 

but I like this one we'll stick with that. All right, so first we have the superior and the 

inferior sagittal sinus. Then there's a straight sinus which connects these two or also called 

a sinus rectus. Laterally you will find the transverse sinus which continues as the sigmoid 

sinus and then as the internal jugular vein. Then we have the superior petrosal 

sinus and the inferior petrosal sinus which drain from the cavernous sinus and 

then we have the sphenoparietal sinuses which go along the sphenoid bone. Then we have the 

anterior and the posterior inter-cavernous sinuses which connect the two cavernous sinuses. And then we have the basilar plexus and 

you know plexus just means a network of structures and the basilar plexus are 

just a plexus of veins that connect different adjacent structures together at the 

basal region of the skull so it connects with the cavernous sinuses, it connects with the 

superior and the inferior petrosal sinuses, and it also goes down and 

connects with the vertebral veins. Then we have the occipital sinus which is the 

smallest sinus and then when the occipital sinus, the superior sagittal sinus, and the straight 

sinus meet, they form the confluence of sinuses. So those are the main dural venous 

sinuses that I want you to know so let's go ahead and go through them in detail. First, we have the superior sagittal sinus 

which remember is the largest dural sinus. It starts at the foramen cecum in the anterior 

part of the cranial cavity and then goes along the superior margin of the falx cerebri and then 

goes back to drain into the confluence of sinuses. Then we have the inferior sagittal sinus. The 

inferior sagittal sinus goes along the inferior edge of the falx cerebri and it receives 

mainly tributaries from the falx itself as well as some small veins from the 

medial surface of the cerebral hemispheres. The straight sinus drains the inferior 

sagittal sinus into the confluence of sinuses. More anteriorly we will find the anterior 

and the posterior intercavernous sinuses which just connects the right and 

the left cavernous sinus together. And notice that I've put in brackets variable 

here because depending on your source they can be anterior or posterior or 

even inferior intercavernous sinuses but the functions are the same, it just 

connects the two cavernous sinuses together. Then we have the basilar plexus which 

remember just connects regional venous structures. Then the transverse sinus drains the 

confluence of sinuses into the sigmoid sinus. The sigmoid sinus is a continuation of 

the transverse sinus and it actually has a pretty cool S-shaped form as it goes towards 

the jugular bulb of the inferior jugular vein. Then we have the superior and the inferior 

petrosal sinuses which drain the cavernous sinus into the sigmoid and the internal 

jugular vein. Then we have the occipital sinus and the occipital sinus is 

the smallest sinus we have and as you see it connects with the 

confluence of sinuses and the sigmoid sinus. Then we have the confluence of sinuses. The 

confluence of sinuses is not really a structure in itself, rather it's just a connecting point of 

the superior sagittal sinus, the straight sinus, and the occipital sinus. So when these three 

sinuses meet they form the confluence of sinuses. Then we have the cavernous sinus and the cavernous 

sinus is actually divided by fibrous septae into small caves and that's where the word cavernous 

sinus comes from it comes from the word cave. And if you look at this picture you will see 

that there are different structures that pass within the cavernous sinus because the cavernous 

sinus is divided into these caves. There's this mnemonic for all of all the structures that go 

through the cavernous sinus which is O TOM CATS. So O stands for the oculomotor nerve 

which is the third cranial nerve, T for the trochlear the fourth cranial nerve, then 

O and M stand for the ophthalmic and the maxillary branch of the trigeminal nerve, C stands for 

internal carotid artery, A for the abducent nerve the sixth cranial nerve and T is just a filler 

in order to complete the mnemonic O TOM CATS. So that was this one. The last one is 

the sphenoparietal sinuses which receive tributaries from the adjacent lobes and then drain 

them into the cavernous sinus to then be drained through the superior and the inferior petrosal 

sinuses and then into the internal jugular vein. So that was everything I had 

about dural venous sinuses. In the next video, we're going to go 

through the branches of these dural sinuses.