 In order to appreciate better the space that is the ischial anal fossa, let's first get our bearings. So here we have the pelvis, which I'm going to make a sagittal cut through. This reveals the three organs of the female pelvis, bladder, the uterus, and the rectum, which becomes the anal canal. Directly lateral to these organs are the muscles of the pelvic floor, which support the pelvic organs like a hammock. The ischial anal fossa are directly lateral to levator anal here. It contains mostly fat, and thus acts as a kind of cushion surrounding the hammock. In this model, we've scraped out all of the fat, which usually fills the space, and so this opening you can see here is the ischial anal fossa, and it's one of those areas of anatomy that is quintessentially hard to grasp in two dimensions, but in 3D it becomes much easier. The space is shaped like a wedge, like this. I'll bring back in the pubic bone for orientation, so I hope that geometry makes sense to you. Let's bring in the lateral wall now, which is the obturator internus muscle, as well as part of the ischium, which is this part of the pubic bone. Let's bring in the medial wall now, which is of course levator anal. So now we see that the space exists between the bowl shaped pelvic floor, and the bones of the pelvis essentially, and as I mentioned, it is filled with fat. The cushioning provided by that adipose tissue allows the anal canal to expand during defecation. As always in anatomy, the form reflects function. The boundaries now, as I mentioned the lateral wall is obturator internus and part of the pubic bone, the medial wall, the pelvic floor muscles, the floor is the deep perineal fascia, and the posterior wall is the sacro tuberous ligament, as well as gluteus maximus. This view might look more familiar to you. This is what we tend to get shown in med school, and if you search ischioanal fossa on Google, this is likely what will come up. It's my hope that after this video, the dimensions of the ischioanal fossa make a little bit more sense to you now. Now if you'd like to navigate around this model yourself, hit the link in the video description below. Thanks for watching, hit subscribe, and we will see you next time.