 Okay, anatomy can be so excited and I hope I can transmit a little bit of this and especially the endoscopic transnasal surgeries they are mainly or highly Anatomic orientated procedures, so we do not use the the fluoroscopy during surgery like we do in micro surgical pituitary surgery You can use the navigation, but don't rely on the navigation and in most procedures navigation is not possible It's a purely anatomical orientated procedure with the endoscope You can reach the skull base from the posterior wall of the the frontal sinus along the cripple form blade sphenoid sinus till to the the second vertebral body, but I will focus on on this area that means the cellar region because this is Something like the epicentrum in endoscopic skull base surgery as I am strict and not say constrained I prefer to do these procedures in a systematic way So we separate these the whole procedure in some virtual Stages called the nasal stage the sphenoid stage and the cellar stage and during these stages I will highlight some anatomical landmarks that are really critical and very important during this Presentation you always have to be aware if you're using an endoscope that you do not have a Virtual image you have always a distortion by the endoscope So this is these are square millimeters You have a distance of five millimeters to your target and you will see that the the structures in the center They appear larger than those you see at the side Yes, but this on the other hand this means if you have a plane Target area the target area seems distorted like this on the other hand if you have like like in sphenoid sinus You have a concave Area like this it seems more or less plain So always remember that if you have this these endoscopic images We heard about these these anatomy of the nasal septum and of the lateral wall of the of the nasal cavity Remember the nasal cavity in the bottom is very wide and it becomes very narrow If you are going to the to the top and it is narrow in the anterior part It becomes wider in the posterior part You see there was no landmark at the nasal septum that's more or less flat You can may have some distortions of the septum or you may have some some spurs But there was there was no defined landmark The only thing is if you have the septum and you have at the bottom the bottom of the nasal cavity You have an angle here and the first step in endoscopic surgery is to follow this angle So you go along at the bottom to reach this area and then you can look up and you find your your landmark So orientate if you're disorientated in a nasal cavity always go to the bottom see this angle nasal septum and nasal floor And then you can reorientate and then the terminates Inferior terminate lateral to the inferior terminate There's nothing special for us and as dr. I showed lateral to the median terminate You see the entrance to the maxillary sinus, which is important for more extended procedures So I want to show a video of a specimen like like a skull base and this is an endoscopic view You see there is the angle septum and the nasal floor There is inferior terminate Middle terminate the cartilage part is removed of course Lateral to the middle terminate. You see the on-senate process and the entrance To the maxillary sinus. This is maxillary sinus here This is midline. This is the rostrum These are the osteas they can vary in shape and size, but they are always there You cannot always see them because they can be covered by mucosa, but they are always there and The rostrum always is a midline structure. It looks like the keel of a ship Yes, and if you see these you know, this is midline. It's always in midline The septum may have some deviations the septis in the sphenoid sinus may have some deviation But the rostrum is always midline so you can orientate by this Okay, first look with the endoscope in the nasal cavity. You see something like this Sometimes you cannot say if this is inferior superior terminate go down and see this Yes nasal septum The floor of the nasal cavity and the the most inferior terminate is the inferior terminate So you see this is inferior terminate This is middle terminate and this is the direction you have to follow in the angle in between the nasal septum and the floor of the nasal cavity and Follow this angle nasal septum floor of the nasal cavity you will reach the nasal pharynx Yes, it's very easy. You see the koane here. This is nasopharynx tubal elevation So you have your first landmark is the koane and then lifting slightly up the endoscope There is koane nasal septum. You see the attachment of the middle terminate here You see the attachment of the superior terminate and you see this is a small hole This is the foramen the osteum to the sphenoid sinus Which is the bony part is much larger than this what you're seeing here and this is called a sphenoid recess so nasal pharynx koane nasal septum attachment of the middle terminate superior terminate anterior wall of the sphenoid sinus on one side and I want to highlight again the sphenopalatine artery because it's important in some cases and The sphenopalatine artery is running through the sphenopalatine foramen and it's dividing two branches Which the lateral branches is called the posterior nasal artery and supply the lateral wall and the conche responsible blood supply the lateral wall and the conches and Posture nasal artery on the nasal septum is running to Supply the the nasal septum and this is important in some cases first if you want to open the sphenoid sinus here you can damage this branch of the sphenopalatine artery and The repleting after surgery. This is the most common cause of a repleting of the nasal palatine artery here So you have to do a good hemostasis at this artery if it's pleated during surgery You can handle it. It's not a problem But you have to do a perfect hemostasis or you will have a repleting after surgery second thing is if we will talk about the nasal septal flap tomorrow nasal septal flap is a flap built by the mucosa of the nasal septum and it's a vascularized flap and the blood supply of this flap This is which is necessary to reconstruct some openings approaches in the skull base The blood supply is running via these arteries So this actually is running here and this is the pedicle of the flap and the flap would be built here so in case if you prepare a flap you have to be Cautious to not to harm the artery or you will have a flap without a blood supply and the third thing is if you're going for Searching for the in more extended procedures you're going for the for some of the video nerve or for the sphenopalatine foramen You follow the artery to reach the sphenopalatine foramen. So it's a landmark to to orientate. I Want to highlight the position of the sphenopalatine foramen? You see this is palatine bone left side right side with a perpendicular plate and a horizontal plate at the Perpendicular plate you have two processes one is the sphenoid process and one is an orbital process and really There's a part of the orbit formed by these Orbital process and there you have the sphenopalatine notch this crest is The attachment of the middle turbinate in the posterior part and these crests is the attachment of the inferior turbinate and if the palatine bone is connected to the body of the sphenoid bone you see these process is connected to the body of the sphenoid and these process to the greater wing and to the orbit and These notch this is the sphenopalatine foramen and it is Superior to the attachment of the posterior part of the middle turbinate You see it in a magnification. This is sphenoid bone. This is palatine bone. This is the koane again so nasal septum here and This is the sphenoid process Orbital process and there's the sphenopalatine foramen and if you're coming from medial to lateral and Removing the mucosa here. You mostly can see this future Then you know you are at this process and follow more lateral you will reach the sphenopalatine foramen and the sphenopalatine foramen Extends to the theoretical palatine fossa, which is here. This is maxillary artery with one terminal branch This is sphenopalatine artery run into the sphenopalatine foramen. You see here What is this? Rotundum second division of the trigonal nerve. You see here the pterigopalatine ganglion Which is connected to the vidian nerve and the vidian Nerve is running like this. So this is foramen rotundum and the vidian nerve is running Here I'll show you yes so you reach the the pterigopalatine foramen you reach by Removing the posterior part of the maxillary sinus. You see here again foramen rotundum Again the anterior wall of the sphenoid sinus You see there is the connection to the etymoid bone with the etymoid air cells You see again the rostrum, which is always midline. You see the osteas very important And what we're doing in sphenoid surgery. There is nothing behind this area. So you can go in here Remove the anterior wall and this is a safe area and now the anterior wall is removed You see some septimes as mentioned. They can vary They can be a middle septum. It can be lateralized and you almost always the lateral septiles are connected to the To the paraclylic carotid. So there are landmarks you can check this on your pre-operative CT scans which is very important and So you have a good orientation in the sphenoid sinus by the knowledge of how are the septums in this Individual anatomy. This is not general anatomy. This is individual anatomy of your patient Yes to the lateral wall of the sphenoid sinus You see the paraclylic carotid carvernous part of the carotid pituitary You see this is second to version of the trigeminal nerve You see here the vidian nerve and the vidian artery Running from the sphenopalatine artery. There was an anastomosis to the carotid artery via These vidian artery, pterigopalatine ganglion Optic nerve of thymic artery and again a slightly oblique view. You see again This is third nerve first division of trigeminal nerve You see here the obtus nerve running to the rellos canal here. These are some sympathetic fibers Running with the carotid artery and here the second division of trigeminal nerve and you see Here this is the anterior medial triangle. So on the other side of this there is the temporal fossa You see this now from the other side second division first division of the trigeminal nerve You see these known triangles This is Parkinson infratrochlear triangle Parkinson's triangle, and you see this is the anterior medial triangle and the anterior lateral triangle and looking from the temporal fossa you have Access in between to the sphenoid sinus Clascox triangle carotid triangle. So looking to the floor of the sphenoid sinus You see this is the anterior wall sphenoid sinus. There were some septis And on the floor sometimes if you have a well Pneumatized sphenoid sinus you can see those elevations here and these are the elevations of the vidin canal So they are running in and sometimes above the floor of the sphenoid sinus Yes vidin canal here running to the genu of the carotid artery at the level of the foramen lacerum And now for us the most important structure is the the posterior wall of the sphenoid sinus one difference between Transcranial approaches and transnasal approaches is that you're if you're doing a transcranial approach You do your approach from from a pretty safe area Yes, you're doing your approach at a safe area, and then you can reorientate to find your target while doing Endoscopic scalpel surgery you are immediately at the side of neuro vascular structure So you have to be really sure where to open and where do we have to take care not to harm neuro vascular structures and you have always To remember if you see this what is on the familiar side? And you know very good this anatomy and you are not that familiar at the moment with this anatomy Yes, so always have to remember what is on the other side of my bony structures The first thing always is to determine the midline so you have the planum sphenoid alle the tuberculum cellae cellar floor and Climus and You pretty often can very easily Determine the midline. Okay, so you first look for the midline and you are here now and Then to go more laterally. This is an oblique view. This is the anterior clientoid process here posterior client we process anterior client a process of the right side and You see the chiasmic limbus here you see the tuberculum cellae here And what is this structure? The optic strike which is a critical structure in endoscopic scalpel surgery So there is a tubercula crest and sometimes a medial Clinary process and these crests of the optic strata the medial crest of the optic strata the tubercula crest and if not absent the crest coming from the medial a clientoid is forming this structure Which is the so-called Medial optical carotid recess? Yes, so here is the medial optical carotid recess in between the optic nerve and The protuberance of the carotid here and this area is Here okay, so you have the optic structure which is a little bit like a drop and the sharp side is medial Here and now you have those two additional landmarks and then looking from anterior You see this again is optic strata and you see the lateral part of the optic strata is the border to the supra-orbital Fisher that means if you're opening the optic strata, which is running like this Here the lateral optic carotid recess is the lateral Border of the optic strata and so opening this you will end in the supra-orbital Fisher where all the nerves are okay in the vertical plane you have those landmarks and now looking for the horizontal orientation and You can very good Orientate by the curves of the carotid in the horizontal way So you have the para farangial part of the carotid you have the horizontal part in the Pedro's bone You have the paraclyle part you have the cavernous part and you have the paraclylonal part and the intradural part of the carotid and A landmark to reach the genu from the Pedro's part to the horizontal paraclyle part This landmark is the video nerve. We have seen it in the pictures before So this is the first landmark for the horizontal orientation and the next landmark is the end of the paraclyle Carotid going to the cavernous part and you see this is you have always have this area This means this is the area of the medial part of the cavernous sinus. You see there is abducent nerve Here so you have here the level of the abducent nerve at this at this area And so we are looking for the most complicated part, which is the cavernous sinus and To look for the cavernous sinus and to understand Once have to look for the laminar and for the membranes of the cavernous sinus like always in brain You have the dura is consists of two parts of the endosteal layer and the meningi layer Yes, so you will have bone you have an endosteal layer. So this is skull base. You have your endosteal layer This is the meningi layer Here and this cavernous sinus is in between the endosteal layer and the meningi layer At the lateral part of the cellar you do not have bones. So you do not have an endosteal layer You only have this meningi layer here and this meningi layer is the layer belonging to the pituitary So it's called a pituitary sac Yes, so the medial wall of the sphenoid sinus is the meningi layer of the pituitary and in between The meningi layer and the endosteal layer. There's the inter cavernous sinus flowing Okay, and in between the cavernous sinus you have some vessels you have sometimes fat You have some nerves the third nerve the fourth nerve and the first division of the tritimular nerve They are attached to the wall of the sphenoid sinus. They are not running in the wall of the sphenoid sinus But there is an archnerid layer running around these nerves so it is not a dual layer is an archnerid layer and These layer attaches those nerves to the lateral wall of the sphenoid sinus The only nerve which is without these archnerid layer is the six nerves up to some sort of nerve So the up to some nerve is running Extradural because you have lost his layer and when do the nerves are losing their layer They are losing their layer while passing the foramen. Yes, and the foramen for the up to some nerve is the rellos canal which is more proximal and At this level the the up to some nerve is passing the endosteal layer and there he loses the archneridal Sheet and so he's the free floating nerve in the cavernous sinus And the other nerves are connected via these these are little layers to the wall And there were some membranes running from these archneridal layers to the carotid. I will show you So you see few from anterior you see this is the endosteal layer Which is removed in the lateral part. This is the lateral compartment of the cavernous sinus here the middle compartment lateral compartment You see this layer is forming this structure and This is the distal dual ring. So it's formed by the endosteal and meningiol layer of the cellar and of the horizontal plate you see later and Going more ahead you see part of the endosteal layer is removed And this is the meningiol layer of the pituitary and it's running around here Yes, and this is the wall of the cavernous sinus and in between those two layers There's the inter cavernous sinus running here and here and here is an artery Which is the inferior hypofusil artery or coming from the horizontal part of the carotid artery and It's the responsible for a flat supply of the the pituitary. So inferior hypofusil artery and You see it again here. You see this is the meningiol layer of the pituitary and you can you can separate the pituitary with a plant dissection from these layer Inter-cavernous sinus and again the inferior hypofusil artery and Only to show these are the super hypofusil arteries They are very important not only for the blood supply of the pituitary But also for the blood supply of the chiasm So if you damage them it can cause in blindness only to show this is The inter-cavernous sinus superior and inferior and the carotid sinus and this is what it's meant to do The approach till you see the four blue lines. Yes, these are the four blue lines inter-cavernous sinus and the sphenoid sinus So these are the borders of the opening if you're doing pituitary surgery and now looking from above you again see these These layers this layer is forming the distal do a ring. So it's removed here You see this is distal do a ring formed by the horizontal blade and coming from the other side from the cellar Now the anterior glinoid is removed You see distal do a ring and you see this structure and this is the proximal do a ring And this proximal do a ring is running from the outer layer coming from the ocular motor nerve I've seen there are some set ties and this is very frequently and then very stable membrane running from the ocular motor nerve to the carotid and forms actually the roof of the Cavernous sinus in the anterior part. So this is the roof at the level of the proximal do a ring The roof of the cavernous sinus again a few from lateral you see Oculomotor nerve you see this is the membrane running from the ocular motor nerve to the carotid and this is the This membrane forming the proximal do a ring. This is The distal do a ring and in between there is the paraclinal part of the carotid And now the optic strut is removed and removing the optic strut you have access to the spin rate sinus So this is the lateral optical carotid recess you've seen and lateral to the optical carotid recess The nerves in the superior orbital fissure. So we have again these landmarks That means the landmarks of the distal do a ring which is here the the protuberance of the carotid You see here is the protuberance of the paraclinal carotid artery Yes, so this is the level of the distal do a ring superior to it. You are intradural and this is the level of the The proximal do a ring and inferior to the proximal do a ring. You are in the cavernous sinus Inferred to the proximal do a ring. This is lateral cavernous sinus From here to here. It's very tiny space Yes, the medial part of the cavernous sinus can be larger. It depends on the elongation of the carotid How much it's elongated So this is the endoscopic view you see the protuberance of the paraclinal carotid You see lateral optical carotid recess here Medial optical carotid recess here. This is the floor of the cellar. There was tuberculum Protuberance on the left side lateral optical carotid recess and the client was here Few to the intradural space. This is the super charismatic area. You see looking the Trans nasal to the bottom of the chiasm. You see there communicating complex communicating artery a 2 a 2 a 1 a 1 Yes, and there what do you expect there? The laminar terminalis. Yes, and here it's open. So we have a suprachiasmatic root to the to the ventricle to the third ventricle Yes Retrocellar area So the Dorsum cellum has to be removed then you can Transpose the pituitary upwards. You see the memory bodies here You see the tip of the basilari artery P1 Segments you see ocular motor nerve here posterior communicating artery here P2 segments here Oculomotor on the left side And you see Trigeminal nerve here and here's up to some nerve running to Dorelos canal. This is Dorelos canal here okay, and To show the nerves in the lateral part of the of the cavernous sinus you have to remove the bone above the cavernous part of the carotid and Then you can Medialize it and you see here is ocular motor nerve in The cavernous sinus. This is up to some nerve This is trochanal nerve and this is the lateral compartment of the cavernous sinus Which really is a very tiny area or as Kasam said the the cavernous sinus is more inferior than you think it is And it's smaller than you think it is Okay, thank you