 I do not have to say much about it, it just carry an impression of the things in your mind. I mean there is not much to talk about it. So, the same thing, the thalamus seen in different views, lateral view, the top view. The important thing when you are using a microscope and endoscope is what important structures. One when you are entering into the lateral ventricle or third ventricle, you must look at the bulge. The bulge you see from the medial side in this is thalamus and the other important structure is chloride plexus, which will help you orient it towards the important structures. Chloride plexus leads to the phenomenon of Monroe. It is a boundary that if you go below this, you are likely to damage the thalamus from the lateral ventricle. So, these are important structures which you have to identify on the microscope or endoscope. So, I will just provide you different visual impressions of the anatomy in different perspectives. It is just a sea, the thalamus, the structure around the thalamus, chloride plexus forms a sea. It starts from the third ventricle roof and goes into a temporal horn. And when you are in, you are in the lateral ventricle, the thalamus is below the chloride plexus. When you are entering the temporal horn, the thalamus is above the chloride plexus. That is, that is important from a surgical point of view. So, for example, when you are doing epilepsy surgery, you are going through the temporal horn, through the middle of, you are going through the temporal horn. Identify the colloidal fissure. Do not go above it or direct above it, you have to remain below it. So, that is important. Classical, everyone of us grew up with this diagram, this standard diagram. And this is how it looks at a different sections, A, B, C, D. D is the temporal horn. These are, as you have seen in the specimens, the hippocampal area. And when you are operating on this area, you enter into this temporal ventricle, the inferior, this is what is called inferior horn or temporal horn. And below the chloride plexus lies the area which you want to resect in an epilepsy surgery, the hippocampus area. If you retract or injure this area, you will cause problems. So, you do not have to go above this colloidal fissure. Identify the colloid plexus and the colloidal fissure and remain below it when you are doing resecting this area. Do not retract or cause damage to the area above it. And if you follow this, this will follow it into the lateral ventricle. When you are doing a epilepsy surgery, for example, functional hemisphere rot me, then this is a landmark. Same thing seen from above, but you have already seen in the specimens, pharoma or monorail on both the sides. And on this side we are saying, you see a bulge here. This bulge into the ventricle is thalamus. And this is when you are approaching a thalamic tumor, you have to look at the bulge and enter directly into the tumor. So, this is one of the approaches for thalamic tumors, where it is bulging maximally. Let you have a visual impression of all the diagrams rather than talking too much about it. Okay, the same thing which you saw here, a diagramatic. So, you have to enter into the pharoma and monorail, identify the memory bodies, the infundibular recess. And this is the area where you have to, this is the superior view of the same thing as you saw this. So, as I told you, when you enter the ventricle, follow the colloidal fissure which would lead you to the pharoma of monorail. You have to be careful when you are putting your endoscope into the pharoma of monorail. What structures can you damage? You can damage the pharynx. I mean, all of us have seen, you do a third ventricle, ask me, your patients do not wake up. What is happening? You must know beforehand what is the diameter of the pharoma of monorail. It should not be smaller than the endoscope. This has, this may look a funny thing, but it is a happened. You push a endoscope into a pharoma and monorail which is small. You damage the phonics and patients do not wake up sometimes or they have some deficits or a phase E or some, they are not. So, this is important. So, this boundary of the pharoma and monorail is found by the pharynx as you have seen in the specimens also. This is important. Previously, you used to read in the books, you can enlarge the pharoma and monorail by doing some posterior sectional, but it is better not to do anything about it. This is an important structure. You do not want to damage. So, identify the septal because it will not be labeled that this is a thalmostrat vein or the septal vein. So, one thing which is very clear is a curate Texas. So, follow it to the pharoma and monorail. Same thing seen from a different perspective. Infantibular recess, mammillary body and this is the area of your venticulostomy in front of the basilar. Sometimes it is very opaque, then you sometimes have to palpate the posterior clenoid to know where to make a hole because sometimes it is very opaque. You are not exactly sure where the basilar artery may be. So, your approaches are determined by your anatomy and where the legions are projecting into. This is just the same thing as showing different. So, just do not listen to what I am saying, just take a visual impression of all the images. That is all I am trying to say. So, depending on which angle you approach the venticulostomy, you can have a different view. This is what we were talking about when you are entering through the temporal horn. This is the crudal fissure. Below this is the hippocampal area and hippocampus, the past hippocampus, the body of the hippocampus and the tail of the hippocampus which is and along with there is a fimbria which turns upwards and forms a phonics, it is like this. So, you have to remain below this. You identify the crudal fissure and then you reset the hippocampus below it. The hippocampus is very easily identified interoperatively, it is a totally white structure. When you see the temporal horn, the anterior tip, so interoperatively, how do you identify amygdala if you have to remove it? You follow the temporal horn, look at the temporal tip and tear and supiate to that will be amygdala. Amygdala is basically what we call as uncals, temporal uncals. So, uncals houses the amygdala and in relation to the venticulostomy inside you identify the temporal where the temporal horn ends and tear and supiate to it will be the amygdala. This is grey, keep on removing till you get your, if something white comes stop and amygdala is always partial amygdala, never do it complete one. So, just giving you visual impression of the same thing what I have already talked about. If you have any doubts about anotomy, I mean this is you can ask anywhere. So, depending on which the venticules or cavities you want to go here or here or here depends upon where the lesion is projecting, there is no such thing that this is the approach for this tumor. You have to decide depending on where is the projecting and where you cause least damage to the cortical tissue. So, that that will be determined by the lesions you are approaching, lesion or tumor. So, there are so many areas from where you can enter, but most often you enter either through the middle frontal gyrus if the lesion is projecting here somewhere or you go transculosel when you are going intramendicular tumor. Mostly anti transculosel rarely sometimes posterior, posterior is not usually done because there are lots of veins sometimes. So, most often you go anti transculosel because this is the area where the veins are relatively less you can cause less damage. Most critical area of veins is this area and sometimes you have lot of problems with the veins coming where you have to mobilize the veins or you have to leave the dura there. So, it is important when you are operating or going through transculosel approach, always try to preserve all the veins. In the occipital transplants you do not get much veins and clearly you may get away with sacrificing one or two in the system, but this is the area which is very risky when doing a transculosel approach. Sometimes it is a tendency when you are operating to coagulate some veins, never do that. As far as possible try to respect and preserve all the veins because it will leave a lot of post-operative complications and morbidity. So, this is just again a visual impression of if the lesion is pointing here this may be the right approach, if the lesion is pointing here you go transculosel again transculosel. So, depending on where the lesion is pointing you can decide and which approach to use, same thing whether you want to go through the temporal horn or through the transculoselian approach depends upon the where the lesion is, where is the maximum bulk of the lesion is pointing that will decide your approach. Third one, the ideal or the approach will cause least damage to the structures will be exactly in the bed line which may not always be possible because the lesions when there is a tumor they are not be distorted. So, this is the least anatomically the least destructive approach you come like this enter through the septum polysudium in between the two intercellular veins and enter this or most often what we do is we enter the lateral ventricle through the corpus closer we enter the lateral ventricle then follow the phonome and monro and phonome and monro then we decide where the tumors for example, we are doing colloid system something like that. So, in nutshell I mean these are the various approaches which are described for the lateral ventricles all of you have seen this diagrams this is so called populace approach the crosses approach these are little bit less commonly used and here cause the most popular transculosel approach and here then this or sometimes the laminar terminalist approach although this distance becomes quite long and endoscopically of course trans phenyl approach depending on the lesion this is a very nice approach because it causes no cortical injury only thing is you have to identify the corpus closer and it looks easy but sometimes the singlet gyrus are stuck together and you can get lost anything which has vessels over it and does not look absolutely wide is not corpus closer if you are not seeing something it is not wide and you are seeing some vessels or pile vessel it is not corpus closer it is possibly singlet gyrus stuck together and to be sure always identify both the periclosals before you enter into corpus closer if you identify both the periclosals and you say in a wide absolutely wide a viscous structure that is a corpus closer if you enter into the singlet gyrus you can have problems and get lost the two important things to remember is when you are doing transculosel try to select ideal will be to get a preoperative venogram done to know where the veins are then you can decide you cannot me so you can have a cannot me which will not cross most of the major veins and if you get a vein interoperatively try to cut the durian both the sides of it leave it there work on both the sides or occasionally you can try to mobilize the vein but sometimes it may not be possible so you have to decide interoperatively not to which corridor to use it is just a diagram and a representation of various the same thing as I told you this is one which can cause problems identify both the periclosals and go and most often you will enter the lateral ventricle rarely you can be directly into the midline and it's not necessary as you are going to the right side you will enter the right ventricle you can enter the positive ventricle also that's why the importance of colloidal fissure genus admins even if you are going to the right side you may enter into the left ventricle so you have to keep that in mind because the ventricle megalis there is not always symmetrical and your angle is always like this when you're operating it's you're not looking like this you're always looking like this the incisions which are used is a personal choice normally patient is supine and a little head flexion is there not extension little flexion is there you leave two-third and T8 to a corner switcher one-third posteriorly and incision there's so many incisions described that you have to decide which incision you want to use normally I use this or sometimes this this should be more anterior than posterior so ultimately you have to do this much of craniotomy just showing as I already told you various steps of a transcolosal approach and when you are trying to enter the phonome one row it's always have better to have a sagittal MRI and then you can sort of calculate your barhole if you are endoscopic you can sort of simulate where the barhole should lead you straight to the phonome one row and you can draw a line from from one row to this area then you can make your barhole cannot be always standard for all the patients we make a standard barhole but sometimes there can be variations for example whether you want to take a biopsy on the posterior area so you have to angulate or manipulate a position your barhole depending on this angulation of the phonome one row to have tried to make it such that you just get a visual impression of it so I am not this is how it looks like when you have got to laminar terminal is the posterior identify the posterior of the optic chiasma both A1's on this side acomarty and at between the posterior optic chiasma and the acom complex is the laminar terminal is when you are coming from midline like this as you are doing anterior craniotomy and you are coming along the A1 so you follow the A1 up to the acom area follow the optic nerve towards the optic chiasma and in between these two area in the midline is the laminar terminal is and sometimes you open it an aneurysm surgery sometimes you want to enter the and laminar terminus and removes the intraventicular terniform gomas this is how it looks like this is the from the sides this is one side this left side right side septum polycytum septal vein both the manticles corpus callosum has been split so this is the same from this side columns of fornix coraxus we are not normally using these approaches this is what you do in a sitting position when you are approaching a legion the posterior therventicular area there are so many approaches you are basically there are two approaches for posterior therventicular legions either you do a supra-tentorial trans-tentorial supra-serial approach occipital trans-tentorial approach or you do a supra-serial infratentorial approach the approach you choose will depend upon the legion where it is maximally pointing traditionally it is said that if you go from the Poppins approach that is occipital trans-tentorial you are likely to go out and move around the veins but in large tumor the veins are displaced so depending on the projection of the your tumor or the legion you have to decide your approach whether you want to do occipital trans-tentorial or you want to do supra-seribular infratentorial the position in both the approaches is different for infratentorial supra-seribular you have to do in a sitting position most often in sitting position when occipital trans-tentorial you do in a three quarter prone position or sometimes as I often using this standard prone position and with the head with the the body because you have good tables now so if you have a standard prone position you can tilt the table to either side and let the occipital lobe fall so it's not necessary always to have a three quarter prone position with the head and down and advantage of a occipital trans-tentorial approach is I find it better a large legion is two one there are practically no veins in the posterior area second you can cut the tentorium and get a good access to the legion and if required you will cut the fox also and go to the opposite side the view you get is quite wide as compared to any other approach and one should remember that the arachnoid this is this area when you are going through a supra-seribular infratentorial approach the first thing you see after you have cut the veins is the arachnoid the arachnoid in this area normally is very opaque other area the arachnoid is thin and you can see through the arachnoid in this area arachnoid is very opaque if you try to cut this arachnoid bluntly without having a you can injure the veins in this area because this area is thick and you don't see the veins around it so you have to be careful while cutting the arachnoid in this area this is that infratentorial supra-seribular approach as I told you this is a standard described position for the poppins approach with the this area dependent you will you are doing cannot be on the dependent part but it becomes sometimes a little cumbersome it's not easy to make burrows sometimes with the patient this position so I prefer to do in prone position with the patient a little bit tilted when you are approaching the fourth ventricular tumors either you go through the vermis or you through a telovillar access that depends on the size a small tumor plays somewhere as you may have to go otherwise you can just retract these things open this veli-cula retract this is the so-called telovillar and enter into the fourth ventricular lesions in this area the mammary bodies infundibular recess and the area of your ventricular spleen the forearm of Monroe this is a view from the lateral ventricle then once you enter third ventricle you see the mammary bodies infundibular recess and this is the midline and this is the area where you have to make a hole and this is how it should look like at the end I think I will stop here because there is a lot of things you will learn about endoscopic again about it