Anal fissure:There are two intertwined muscle structures that surround the anus and allow us to hold our stool, and they are called the internal and external sphincter. The outer sphincter structure is in striated musculature, and just like our arm or leg muscles, it contracts and relaxes depending on your wishes. The external sphincter is the system that helps us hold our stool until we go to the toilet when we feel the feeling of defecation. Of course, like all striated muscles, it gets tired after a while. Therefore, a mechanism is needed to keep the anus area dry even at rest. The inner one of the muscles surrounding the anus is called the internal sphincter, and it has a smooth muscle structure (like the muscles in the vessel walls), so it automatically contracts and relaxes not by our will, but by the control of some centers in our brain. This muscle, which is constantly contracted at rest, prevents the fluids in the anus from leaking out and keeps the anus area dry. For defecation , when we sit on the toilet, the internal sphincter relaxes and opens the way for the stool to come out. If a person is constipated, the internal sphincter, which is exerted too much force during defecation, does not relax in response to it, instead of relaxing. For this reason, stool that has to pass through a narrow area causes abrasions and wounds on the intestinal wall during this passage. These wounds, which will heal quickly under normal conditions (the skin of the anal area has a very high healing potential), get deeper due to the repetition of the same problem with each defecation and because the internal sphincter, which does not relax, compresses the blood vessels of the region (for wound healing in a region, blood flow to that area is very good. must be). These wounds on the anus wall are called anal fissures.          _cc781905-5cde-3194-bb3b-136bad-136bad5cf3b-136d58359cf1365cf583594cc781905-5cde-3194-bb3b-136bad-136bad5cf1365cf78359cc1365359cc58359cf1365cde78359cc78195 5cde-3194-bb3b-136bad5cf58d_