something about the dural venous sinuses how exactly the venous sinuses are draining and then we'll also understand that what is the direction of the blood flow at times people do understand the dual venous sinuses but they don't understand that what is the direction of the blood flow and they get stuck in the clinical questions like if somebody give you a clinical question that there is a tumor growing in the confluence of sinuses so which sinus will be obstructed to understand this question to answer and answer the questions like these you should know that where the blood is starting where it is going which science it goes into how it comes out and all so guys look at some dural folds here again with the help of these pictures look at certain dural folds and these dural force are holding the dural venous sinuses now the dural folds the dural folds which are required to form the dural venous sinuses are named as fox cerebri there will be fox seri bellai there is tentorium guys tentorium cerebelli tentorium cerebellar and there will be diaphragma diaphragma cell diaphragmatic cell that is covering the cellular testicle so we call it diaphragmatic cerebri fox cerebellite tectorium cerebral and diaphragmatic fox means sickle shaped anything which is shaped like a sickle is called as a fox so if you look at this image here this here is a fox cerebri it is basically dividing the two cerebral hemisphere it is present between the two cerebral hemisphere here so this is fox cerebral here so this neural fold here is fox cerebri a similar dural fold will be present between the two cerebellum which is below here that is called the fox cerebellar it's a very very small fold you can see the fold and sinus together only but see what is to be noted first that fox cerebri is having two dural venous sinuses one in the upper margin and one in the lower margin the sinus guys and again the important thing is the direction of blood flow this sinus is present in the genital plane above so we call it what sinus it's a superior sagittal sinus whereas the one in the lower part this is called as the inferior sagittal sinus superior circle and inferior central sinus the blood flow is like this guys superior cell sinus is carrying the blood backward like this inferior cycle sinus is also carrying the blood backward and downward like this then you see this inferior digital sinus is draining the blood into this sinus which is running backward now this is taking the blood backward guys this sinus here which is taking the blood backward this sinus is called as a straight sinus this sign is taking the blood backward here that is called as a straight sinus right that's straight sinus this straight sinus when it takes the blood backward here at this point here this is also receiving the blood from below coming from fox cerebelli coming from fox cerebelli now the name of this sinus because the sinuses in relation to the occipital bone so we call it occipital sinus this sinus is called as an occipital sinus which is taking the blood upwards it is taking the blood upwards now you can see superior inferior straight they're all kind of meeting at this point here and that's why this area is called as the confluence of sinuses this is called as the confluence confluence of sinuses meeting point of sinus guys meeting point is confidence it's a confluence of sinuses or meeting point of the sinuses here once the blood reaches the confluence of sinus c our main motive is to take this blood out of the cranial cavity we have to drain this blood out how are you going to drain this blood out here from the conference of sinuses the blood is going into this sinus and that sinus is present in the tentorium cerebelli we call it what we call it the transverse sinus i'm going to show that in the next picture also but just just write it for i'm just remember it this sinus here is called as a transverse sinusoid i'm writing t s the ts there stands for the transverse sinus that's the transfer sinus right now from the transfer sinus the blood ultimately goes through this sinus downward into the jugular foramina this is where the jugular foramen will be present it is covered with durameter as of now and this sinus here is called as a sigmoid sinus look at the shape guys this this sinus is like a sigma shape here so we call it what sinus that's a sigmoid sinus that sinus over there is called a sigmoid sinus and what you can see that this sigmoid sinus is meeting with one sinus which is coming here and then they together are going out of the jugular foramen here now understand one thing here in this picture what part i'm highlighting here guys this bone here is a petrous part of temporal bone whatever i've highlighted here for you this is a peters part of temporal bone so you can see a sinus running on the upper margin of petrous temporal bone and on the lower margin of pitra's temporal bone and that's why these cyanus are called as superior petrosal sinus and inferior petrol sinus guys this sinus here is sps superior petrol sinus which is taking the blood backwards and this is also taking the blood downwards and backward is eyepiece that is inferior petrosal sinus superior petrol sinus is going into transverse inferior petrol sinus is joining with what is sigmoid sinus so what you see here the sigmoid sinus it is joined by what sinus it is joined by the ips that is inferior petrosal sinus it is joined by the inferior petrol sinus and then both these together the sigmoid and the inferior petrol sinus once they comes out of jugular foramen they together will give rise to the internal jugular vein now that also is a question how internal jugular vein is formed internal jugular vein is formed by the two sinuses one is this that is sigmoid and the one is this that is inferior petrossal when these two sinus they join with each other it together forms the vein and that vein is internal jugular vein that is an internal jugular vein let's say internal jugular vein now to me what is important here for you to remember the direction of the blood flow guys look at this superior petrossal taking the blood downward inferior petrol taking downward then we go backward that's a straight sinus here receiving the blood from where occipital sinus all the blood get collected into the confluence from the confluence and goes into transverse then it goes into the sigmoid like this right and sigmoid joins with inferior petrosal and then forms what wayne internal jugular vein that's how the blood majority of the blood is coming out of the cranial cavity but have you noticed that where the superior in the inferior petrol sinus is coming from this superior and the inferior petrol sinus it is actually coming from the cavernous sinus here on the side of the pituitary fossa that's the side where cavernous sinus is present i'm going to show it in the next picture also but just to tell you here guys cavernous sinus in this image is here so that's how the cavernous sinus is actually throwing the blood backward it is it is draining the blood backward via superior petrol sinus and inferior petrol sinus superior goes into transverse inferior joints with sigmoid and i told you that if the clinical questions like there if there was a question that uh a tumor is occluding the confluence of sinus if there is any tumor which is occluding the confluence of sinus then which of the following dural venous sinus blood will get obstructed so they gave the options of like transverse sinus superior petrol sinus superior genital sinus like that so obviously superior cycle sinus is the one which is coming towards the confluence of sinus so any blood which is coming toward the confluence will get obstructed not the one which is going away from the confidence and that's why the the direction is important here let's look at the same thing in the transfer section guys if i if i take a transfer section of cranial cavity see how this is going to look like here in the transfer section guys this picture is going to look like this now let me take your attention to backward to this here this sinus here is once again the straight sinus look at that that's the straight sinus and what is to be noted in this picture which you could not appreciate in that section here that the blood of the transfer straight sinus mainly it goes toward the left side mainly i'm not saying it is going to the confluence also but mainly it goes toward the left side and the superior cycle sinus is the one which is going backward here once that superior circle sinus blood is the one which is mainly going toward what side toward the right side so it's the superior genital sinus which mainly continues to form what sinus the right transfer sinus the right transfer sinus whereas a straight sinus continues and gives its blood mainly in the left transverse sinus although they are meeting here guys look at this this entire is a meeting point for all these signs that's a confluence of sinuses but if the question is asked to you that right transfer sinus receives the blood mainly from where so it is receiving the blood mainly from the superior dietal sinus the right transfers whereas the left transfer sinus is receiving the blood mainly from with sinus it is mainly receiving the blood from the straight side so you can see the straight sun is mainly curving toward the left side here then we know the transverse sinus that drains the blood into sigmoid so in this picture here i can see at least on one side that's a sigmoid sinus right that's a sigmoid sentence you already know about that let me again remind you where is the petrous part of temporal bone here is the petrous part of temporal bone if this is a petrous part of temporal bone you can see the two sinuses coming backward this is sps that is superior petrosal sinus and this is inferior petrosal sinus the superior petrocell inferior petrossal which are coming from this largest dural venous sinus and that is what that's a cavernous sinus that's the cavernous sinus guys that's the cavernous sinus so what i can make out from this picture is that whatever blood comes into the cavernous sinus whatever blood comes into the cavernous sinus it is drained by the two main sinuses one is superior petrossal the direction is this and one is inferior petrosal which is in this direction which is meeting with the sigmoid right and they both will go out of the jugular foramen here the important question now is where cavendish sinus is receiving the blood from you it is about the outgoing these are the outgoing channels here sps ips are the outgoing shells what about incoming guys where the blood is coming from cavernous sinus is receiving the blood from different sinuses different sources i would say if i just take you on the upper part of this picture you can see kevin's sinus receives the blood from the orbit it receives the blood from the brain and it also receives the blood from the meninges also so guys input the incoming channels of cavernous sinus if i talk about the incoming channels of cavernous sinus in this image only the incoming channels of cavernous sinus guys first of all from orbit so there are certain veins which are coming from the orbit and draining into the cavernous sinus and those veins are ophthalmic veins like we have superior and inferior ophthalmic veins superior and ophthalmic vein sometimes central vein of retina also sometimes central vein of retina will also come and drain into the cavernous sinus so we have superior ophthalmic when in fear of telomere and central vein of retina not always sometime it can also come back and drain directly into cavernous sinus so this is the blood coming into cavernous sinus from where from orbit another incoming channel from the for the cavernous sinus is from the brain there are certain veins which are coming from the brain and directly draining the blood into cavernous sinus you have to remember these names for now one of them is called as superficial superficial middle cerebral vein superficial middle cerebral vein and then we have inferior cerebral vein inferior guys inferior and not internal be careful it's inferior not internal superficial middle cerebral vein and there is a one which is at the base of the brain called as inferior cerebral vein and finally cavernous sinus is also receiving the blood from meninges that means there are some dual venous sinuses draining directly into cavernous sinus again you have to remember these names for now one of them is called as spheno parietal sinus i can show you this phenotypical sinus in the picture guys pheno parietal sinus and one another one is called as the middle meningeal sinus middle meningeal sinus like middle manager sinus or middle meningeal vein so middle manual sinus so these are the incoming channels now that's again important here the incoming channels of cavendish sinus cavernous sinus is receiving the blood or the tributaries which are coming inside the cavernous sinus are coming from orbit are coming from brain and are coming from managers and these are the ones you have to remember the names that these are the incoming channels of cavernous sinus incoming channels fine we just said guys what about outgoing channels now when i say outgoing channels of cavernous sinus when we talk about the outgoing channels of cavernous sinus you already have two names in your mind the petrocell one of the outgoing channels of the cavernous sinus is super superior petrossal superior petrol sinus which you saw draining into the transverse and then there was inferior petrosal sinus then there was inferior petrol sinus which is draining into the sigmoid or joining with the sigmoid here and here is one more guys and that is superior of thalamic vein and don't be surprised by looking at superior ophthalmic vein in the outgoing channel i'll tell you why superior petrossal inferior petrossal and superior of thelma queen now you will say that superior ophthalmic vein we also wrote this here as well in the incoming channels and i'm writing it outgoing yes it is there in both superior ophthalmic vein is an emissary vein emissary veins are the veins without valve there is no valve in it so blood can go out through them and the blood can come in through them so anything is possible guys superior ophthalmic when is not having any valve so it can allow the blood to go out also allow the blood to come inside so it can act both as incoming channel and also as an outgoing channel also so you have to count that in both here so this is about the cavernous sinus the incoming channels and the outgoing channels here and that's how you're going to identify them the related relative things on the on the on the picture here obviously nobody's going to ask you to identify these veins on the picture if it at all it has to be identification of the dual venus sun it's a very simple one either they will ask us to legal confluence sigmoid or any sinus which is in the posterior cranial fossa here you should be able to identify the sinus in the posterior cranial fossa mainly right so this is a little about the the dual venous sinus that you should know about now i need to quickly tell you about some important relations of cavernous sinus also because governor science relations are important guys kevin sinus is having some important media lateral relations and there are some important clinical aspects which are related to it here so let me just add a topic of discussion here itself we'll keep it very simple we don't have to draw anything complicated here guys in the relations of cavernous sinus guys let's say if this here is covered in sinus in the coronal section remember that what we're discussing here it is a coronal section see on the medial side on the medial side you will see that the body of sphenoid with sphenoidal air sinus seller tursica will be there so all this pituitary gland is also there as well so medially medially pituitary gland the cella turcica and these sphenoidal air sinuses the sphenoidal air sinuses guys these are the medial relations of cavernous sinus these are present on the medial side of cavernous sinus every relation is important clinically it's important there's so many syndromes which are related to the cavernous science guys uh superior orbital facial syndrome you know cavernous sinus carotido cavernous fistula you know a pulsating proptosis so for that you need to know the relations here so pituitary gland cellar tursica sphenoidal sinus they are on the medial side in the floor of cavernous sinus is foramen lesser forum in lesson guys that means it is resting on the forum and lesson here the cavernous sign is resting on the forum lesson so this is in the floor in the lateral wall third nerve fourth now ophthalmic now oculomotor nerve shock clear now and ophthalmic nerve and ophthalmic now are in the lateral wall along with along with the primary auditory area guys that is unkus there is a part of the temporal lobe called as ankus that is also present toward the lateral side here so toward the lateral side this gyrus here this gyrus basically is a primary olfactory area and this primary olfactory area which is a part of temporal lobe is called as an uncus anchors so these all relations are present toward the lateral side they are all lateral relations so third now fourth now ophthalmic now along with anchors here maxillary nerve guys i'm not drawing here many atlas shows maxillary in the lateral wall but according to gray's 41st edition it says maxillar is not in the lateral wall it is outside and below the lateral wall of cavernous sign so let's go with the grey's anatomy in this it just includes three nerves in the lateral wall of oculomotor trochlear and ophthalmic what is inside inside the cavernous sinus we have internal carotid artery it is going through it internal carotid artery and just inferior lateral to the artery is the abducen nerve also so these structures are inside guys these structures are inside the cavernous sinus internal carotid artery and what now sixth now abducent no the only nerve that you see which is running through the cavernous sinus here so these two structures are present inside or running through the cavernous sinus internal carotid artery is not only running inside the cavernous sinus it makes a carotid siphon it makes a loop and comes above the cavernous sinus also so you will see internal carotid artery is present above the cavernous sinus along with optic asthma along with optic chasma here so once again guys internal carotid artery and optic asthma these two structures will be seen where in the roof of the cavernous cyan in the roof of cavernous science so in this section i can make out the floor is having foramen lesser roof is having internal carotid artery and optic asthma the structure running through cavernous sinus is internal carotid artery and six now in the lateral wall we have third now fourth now of thalmic now and ankus and medial relation is all this pituitary gland cellular torsicas phenolic sinus these are all medial relations of cavernous sinus because it's a coronal section so i cannot see the anterior and the posterior relationship guys what is anterior and posterior relation of cavernous sinus that can be understood from this previous picture only look at this guys if you look at this image here the anterior relation of cavernous sinus is a superior orbital feature can you see that that's a superior orbital fissure here and the posterior relation of cavernous sinus is an apex of fetus temporal bone what bone is that that's a petroleus part of temporal bone so apex of the fetus temporal bone is a posterior relation so again the two relation that i would let me write that for you that anterior relation the one which is not mentioned here the anterior and posterior in the coronal section so what is the anterior post relation here guys the anterior relation is this superior orbital fissure and the posterior relation is the apex apex of petros temporal wall apex of the petrous temporal wall so these are very very important relations of cavernous sinus this is what you need to know about the dura mater and dural venous sinuses guys you should know about how the sinuses are running what direction the blood is running into how it comes out how internal jugular vein is formed then straight sinus goes toward the left side superior subjective goes toward the right side and then cavernous sinus incoming channels outgoing channels again very frequently asked question about the cavernous sinus incoming and outgoing channels and the relations of cavernous sinus are important they are important from the the clinical perspective also no keratido cavernous festival if the carotid internal carotid artery ruptures inside the cavernous sinus that will lead to the keratito cavernous fistula and that caterpillar cavernous fistula can push the content of orbit every pulsation of internal carotid artery will push the content of the orbit and can cause pulsatile proptosis also this is something that you will read or must have read in the ophthalmoid but just a anatomical basis that because cavernous sun has anti-relation is superior orbital fissure so if there is a pulsation of the cavernous sinus there will be pulsation of the orbital content as well which leads to pulsatile proptosis pulsatile proptosis