Ischioanal Fossa Anatomy: Boundaries, Contents & Clinical Importance

[00:00:01]Bismillah Rahmanirrahim. Today our topic of discussion is Ichkyo Anal Fossa.

[00:00:07]A This video is just for second year MBBS.

[00:00:13]A di topic is abdominal pace. And in this, the Essen Canal was one of our topics. Let's discuss this quickly.

[00:00:22]It is basically also known as the rectal fossa.

[00:00:30]Okay and shape, what about its shape, it is a wedge shaped structure on either side of the anal canal and paired along with fat field space.

[00:00:49]If I show it in the picture, then in this picture, you will see this fatty and wedge shaped structure in pink color, okay, the wedge shape is more or less like this, which will have an apex and a base, okay, we will have one apex base, one lateral wall and one medial wall which will be towards the anal canal, we will have the medial valve which will be of the second type, we will have the lateral valve, so look, you can see this pink colored structure, okay, this is the anal canal, okay, and here we have two, let's say, fat field spaces on both its sides, if we consider its function, it is for the expansion of the anal canal during defecation. Ok? So during defecation we have it helps and allows the anal canal to expand. Ok? So, by expanding it from here, we can have an anal canal behind its boundaries. Ok? So this is the function we have about why it is. Let's talk about measurement. It's a 5 cm. In length, 5 cm. In depth end 2 5 cm. This width is done. Ok? If I talk about length then it is 5 cm. If I talk about width, then its thickness is 2.5 cm. If I talk about depth, then if we measure its depth, it will be almost 5 to 6 cm. It became in depth. Ok?

[00:02:16]Now let us quickly talk about its boundaries.

[00:02:18]A boundaries r lateral valve. As I already discussed lateral valves, medial walls, apex and base. Ok? The lateral wall is formed by the scium and obturator internus muscles. Ok? Scum is a bone of the pelvis.

[00:02:34]Ok? So we can see all these bones with us. Ok? That is the scum bone. And what we have underneath this is the obturator internus muscle.

[00:02:44]So we have this anal canal. This is the middle boundary of the anal force that we have.

[00:02:49]This is the lateral boundary. So the lateral ligament is formed by the obturator internus muscle and the ischium bone of the pelvic ligament. Ok? The pes has three parts: the ileum, the ischium, and the pubis. Ok? Ilium, ischium and pubis. Ok?

[00:03:04]So, let us call it the tuberosity of the scheme that we have, you can see it here and what all of this do we have, yes, on the lateral side, obturator internus and we will have this bone, we will talk about the middle wall, so this medial wall of ours will be made of this, this is the middle wall of the pink, that is found by lateral and eye and external anal spinner, how many types of anal spinner did we have, there are two major types, external anal spinner and internal anal spinner, internal is involuntary, it is not in our control, whereas external is voluntary, it is in our control. Ok? So the external anal splinter that we have is what brings it here.

[00:03:39]So the middle wall is found by external anal splinter and one we have is the muscle which we have elevator and I will come to us. Ok?

[00:03:46]Posteriorly, behind this we have a big muscle of the buttocks. Ok? That is the gluteus maximus. And we have the sacrotuberous ligament, from the sacrum to the gluteal tuberosity, whatever is there with us, what will we get. Ok? Now let's talk about the floor. The floor which we have is on the lowest bottom side, which we call the floor.

[00:04:09]Ok? So what will we have to make of it? Perineal skin. All the skin here will form the floor.

[00:04:17]Who made the roof that is the top of it?

[00:04:18]Fascia covering the obturator internus and inferior fascia the pelvic diaphragm. Ok? So this obturator internus muscle has a fascia around it which forms the floor of all of it here. Now let me show you the picture. Ok? Now inside its lateral wall, he's saying we have a canal here, which he's calling the pudendal canal. Ok? Or it may have been given another name, A K Alcock Canal.

[00:04:42]Ok? So you have to remember what we have in this? You will find the pudendal nerve, pudendal artery and pudendal vein here. Ok? So what we've discussed so far about anatomy is on each side of the perineal orifice. This is the perianal orifice. Above each side of this we have, let's say, this perianal space. Ok? In which we will have the perianal fascia and the below perianal skin.

[00:05:08]Ok?

[00:05:11]So if we further modify the picture or enhance it further, then we can now see it in transverse view.

[00:05:18]So what we have is the anal canal. This is the anal orifice. Ok? So on both its sides, on the lateral side, we have the fat, the shape structure that is inside the pink, we have all of it on both its sides, that is the anal or rectal, we have psoas. Ok? And here if we talk about bondage of the middle wall found by elevator NI and external anal splinter. Whatever is there here is the anal, so whatever is outside it is the external anal sphincter and here the levator NI will be a muscle. Ok?

[00:05:54]And what did we have on the medial side, Liberator NI and External NI, on the lateral side? Obturator internus and we had scale tubuosity, whatever was there, we had all that muscle and this scale tubuosity. Ok? So that is being shown here with us. The length mentioned was 5 cm. We had the length. 5 2.5 cm The width was 5 cm. We had the depth, all of it and this AKL canal which we had, where I showed you, we have Alcock's canal, it is also called as pudendal canal, its other name is also pudendal canal, you can see it on both the sides, what content is there inside it, from the pudendal canal we have pudendal nerve, pudendal artery and we have pudendal vein, it will move majorly from here, so look here, if anyone still does not understand, then here we have this obturator internus muscle, all of it, that is bone. This is the whole thing that we have here which is visible in yellow color, so we have all those skulls.

[00:06:59]That's the external N specter. And this thing that you see is the elevator NI. So medial wall is found by liberator NI and external NI spector. The lateral wall is found by the still tuberosity and this is the obturator internus muscle. Ok? So we have the same structure.

[00:07:18]Hopefully, now some map would have been formed in your mind.

[00:07:20]Ok?

[00:07:21]The fascia covering the obturator internus, all of it, is coming to us on top of the roof. Ok? So what we just talked about was the roof. Ok? So here we have the roof is formed. Fascia covering by the obturatus internus. This entire muscle was obturator internus. So around this we have a fascia that is that form the roof of this so this fascia was covering everything here. Ok? Now the fascia covering the pelvic diaphragm, the fascia covering the obturators, what was all this making us have? Was building the roof. Who was making the floor? All the skin we had was making the floor.

[00:07:58]This entire pudendal canal is here. One is this alk canal which we had named above the lateral wall. We will have right and left on both sides.

[00:08:05]What is the content? The pudendal nerve, pudendal artery, and internal pudendal vein, we have them all here.

[00:08:11]Ok? Now this is what we have about the perianal space.

[00:08:16]Below this fossa, you can see a space in pink colour, that is the perineal space. Ok? What's inside it? You might be able to see this from the septum inside. So this space is further divided into numerous compartments by fibroelastic septa. Ok? So here are these fibroelastic scepters of fibrowhitish color which divide them. The fats are arranged tightly inside the space and we will have them in the form of small locky eyes. So any infection in space will be very painful.

[00:08:47]That is known as perianal abscess. So, let us say that there will be any infection inside this anal passage and mostly the infection that occurs here is due to any injury on the anal canal.

[00:08:59]Ok? The injury has occurred due to any reason. It came that the injury here was caused due to hard fecal, constipated fecal or hard stool.

[00:09:05]So the bacteria that is here will enter us. Ok?

[00:09:10]Or if there is any such injury here, then what will happen to us is that all the infection will go inside this panel space.

[00:09:16]That will form the perianal abscess. Ok? The pass will be made there. So that is the appearance that is a very painful condition for the patient. Ok? So we had this. So what is content? Of space we have subcutaneous part of the splinter and I external muscle external hemorrhoidal venous plexus and we have fat. There will be fat.

[00:09:33]Ok? Here we will bring all the venous plexus veins and hemorrhoidal veins here.

[00:09:39]And apart from this, we have subcutaneous which will be a part of the spindle and eye external muscle. Ok? And through included by a sensitive skin, all of this will be included with us.

[00:09:48]Ok? We will have this. Now we have to do it only according to Snell because there is a lot to teach but you will read only what is written in Snell because the exam will come from there. Ok?

[00:09:59]If I simplify this further, it is your fossa. Ok? This whole thing that you have above is the urogenital diaphragm.

[00:10:05]Ok? Below we have the pelvic diaphragm. In the middle we have the perineal body. Where all the muscles come and get attached. Ok?

[00:10:12]What do we have here now? Yes, down below we have all these anal canals.

[00:10:15]So, this anal canal has a wedge shaped structure present on its lateral side.

[00:10:20]Ok? Contains fats.

[00:10:24]Ok? That allows the anal canal to expand during defecation. So we will have all those fossas here.

[00:10:29]Below this, what we have is the posterior cox and coxsack.

[00:10:34]Ok? What will we have anteriorly? The pubic symphysis will be here. So I have asked you to draw a map, is this okay? Now if I elaborate on this further, I have shown it in the picture.

[00:10:44]This is something I drew. This was the anal splinter we had. That is the internal anal sphincter. And what will we have outside? This external anal splinter.

[00:10:52]So, on the lateral side of its external anal splinter, on the right side as well as on this side, we have on both the sides, the entire NL or this rectal fossa, which we had, will be here. Its bone is being brought here to us. Above we have Silbetter Enai. Here's all the facial that's making the roof.

[00:11:08]Below we have all the skins.

[00:11:09]Here we will have the perianal space in which there will be infection, so we will have a whole lot of perineal effusions.

[00:11:14]We have a slender canal here, through which we have a whole range of nerves, arteries and veins.

[00:11:21]Ok? This is what we had superficially which I wanted to share with you. Hopefully, if not much, then something or the other must have remained in your mind.

[00:11:30]Ok? Ok? If you take a screenshot of this, I think that's more than enough for this exam. Ok? So if anyone has any issue here, please tell us in the comment section.

[00:11:39]And for the rest of the subscribers, please, I had some students of second year anatomy who wanted to understand this, so I have specially arranged this lecture for them.

[00:11:47]Ok? That is the perianal fascia, perianal skin. All of this is on the bottom side. Ok? Here I'm showing all the fibroblastic septa that are dividing the space. When it gets divided into space inside it, that forms the small loculi. Ok? So we will have all these small loculi.

[00:12:04]Ok? The subcutaneous part of the we have this external splinter. Ok? And here we have all the external hemorrhoidal venous plexuses that we have.

[00:12:13]Ok? So we can see it here.

[00:12:15]Ok? And this structure that he showed us here is the rectal or isal fossa, the same thing. Ok? So apart from this, the small nerves like dorsal nerve of penis and perineal nerve also bring us here.