Anus (Human Anatomy): Picture, Definition, Diseases, & More

The anal canal, which measures 3.8 centimetres in length and is located in the perineum just below the pelvic diaphragm, is the last portion of the large intestine.

The anal canal is located in the perineum's anal triangle, which is located between the fat-filled ischiorectal fossae on the right and left sides of the perineum. These fossae allow for the expansion of the anal canal that occurs during defecation.

The anal canal starts at the anorectal junction and travels downward and backward before opening at the anal orifice, which is located in the natal cleft (cleft between the buttocks), approximately 4 cm below and in front of the tip of the coccyx.

Following are the main functions of the anus:-

• Release of feces: Anus contains anal sphincter muscles which control the release of feces. Anal Sphincter muscles are located all around the anus and have a significant impact on a person's capacity to maintain control over their bowel movements.
• In addition to its role in elimination, the anus is also involved in sexual activity for many people. The anus is surrounded by sensitive nerve endings and can be a source of pleasure and stimulation for both men and women.
• Release of Gas: The muscles in the wall of the anus, known as the anal sphincters, can relax or contract to control the passage of feces and gas.
• Also prevents us from pooping involuntarily: When we get the urge to use the restroom, our external sphincter tightens to keep the stool in our digestive tract until we reach a toilet, at which point it relaxes and allows the contents of our stomach to pass. This process continues until the next time we get the urge to use the restroom.

• Internal hemorrhoids: Internal haemorrhoids, also called true piles, are the sac-like enlargements of the branches of the superior rectal vein (also called the haemorrhoidal vein) that are above the pectinate line in portal obstruction. There's a chance that the internal haemorrhoids are either the first or the second ones. Primary piles are caused by enlargements of the primary tributaries and radicles of the superior rectal vein, which are in the anal columns and are on the left side, right side, and right side, respectively. You can find these piles in the anal columns. Secondary piles are the enlargements of the radicles of the superior rectal vein that happen in other places. When you are in the lithotomy position and looking at the inside of the anal canal, the primary piles are at 3 o'clock, 7 o'clock, and 11 o'clock on the anal wall.
• External haemorrhoids (or false piles): External haemorrhoids, also called 'false piles,' happen when the branches of the inferior rectal vein below the pectinate line get bigger. They are covered by a thin layer of mucus in the lower half of the canal. When you strain to go to the bathroom, they hurt a lot and don't bleed.
• Anal cancer: Cancer of the Anus Cancer of the anus is an exceptionally rare form of cancer. The risk of acquiring cervical cancer is increased by a number of factors, including infection with the human papillomavirus (HPV), having several sexual partners, and engaging in anal sexual activity.
• Anal herpes: Sexual contact with the anus can transfer the herpes viruses HSV-1 and HSV-2, which can cause an outbreak of herpes anal. One of the symptoms is a painful sore that develops around the anus and then gradually fades away.
• Anal warts: Warts in and around the anus can be caused by an infection with the human papillomavirus, sometimes known as HPV. Anal warts are the name given to this ailment.
• Anal abscessx: An anal abscess is a localised infection that occurs in the soft tissue that surrounds the anus and can be quite painful. It is possible that antibiotics and surgical drainage will be required in order to treat an abscess of the anus effectively. If this is the case, the treatment will involve both methods.
• Anal itching: Itching in or close to the anus is a common problem, and itching in the anus can manifest itself in any part of the anus. In the vast majority of cases, there is not a single primary contributor to blame.
• Diarrhea: Diarrhea is most commonly brought on by a virus, but it can also be brought on by consuming tainted food. Viruses are the most common cause of diarrhoea. It is possible that it is a symptom of another disorder, such as irritable bowel syndrome or inflammatory bowel disease; however, this occurs significantly less frequently than it used to.
• Proctalgia fugax: Pain in the region of the anus and rectum that comes on suddenly and is extremely severe. This type of proctalgia fugax typically lasts for a few seconds to a few minutes before subsiding. There is no clear explanation for why this is happening.
• Constipation: Constipation, which can lead to abdominal pain, fissures in the abdominal wall, and bleeding from the haemorrhoids, is characterised by the inability to pass faeces easily. This is one of the most common symptoms of constipation.
• Anal bleeding: Haemorrhoids are one potential reason of bleeding from the anus; nonetheless, it is critical to get checked out to eliminate the chance of a more serious underlying condition.
• Fissure in anorectal canal: A solid quantity of faeces has the potential to crack one of the anal valves, also known as the valves of Morgagni, and create a fissure in the anorectal canal. They occur behind the midline and are extremely painful due to the fact that the lower part of the valve is covered by the skin or mucous membrane of the lower half of the anal canal, which is supplied by somatic nerves. This makes them very difficult to diagnose.
• Fistula in anorectal canal: The aetiology of this condition is the bursting of an abscess that was surrounding the canal. The abscess opens spontaneously both internally into the anal canal as well as externally on the surface, and the track afterwards becomes epithelialized. The most common type of anal fistula is one that occurs at a low level and passes through the superficial layer of the anal sphincter.

• Rectal exam: The lower rectum can be checked using a digital rectal exam. The doctor or nurse will examine the area with a gloved, lubricated finger to look for anything out of the ordinary.
• Abdominal X-ray: An X-ray of the abdomen is used to visualise and examine the abdominal organs and medical conditions such as intestinal perforation or obstruction.Computed Tomography (CT Scan): A CT scanner employs X-rays and a computer to produce images related to the abdomen and its structures. This technique assists in the analysis of the abdominal conditions e.g., appendicitis and cancer.
• Magnetic Resonance Imaging (MRI Scan): It is a medical imaging technique or technology. This method employs computer generated radio waves in a magnetic field, to produce detailed images of the abdominal structures, such as liver, gallbladder and pancreas etc.
• Abdominal Ultrasound: It is a non- invasive procedure, which is employed to analyse abdominal organs or structures.It employs transmission and reflection of the ultrasound waves to visualise and detect problems in the abdominal structures e.g., gallbladder, kidneys and liver.
• Biopsy: It is a medical diagnostic test, in which a small sample piece of tissue is taken and tested in the laboratory, which is used to diagnose medical conditions such as cancer, liver or other medical problems etc.
• Physical examination: In certain cases, a doctor will evaluate the surface of the anus before inserting a gloved finger into the anus to examine the inside of the anus for abnormal areas. This is done in order to detect any anomalies.
• Fistulography (fistulogram): The X-ray images produced after injecting a contrast dye into the opening near the anal canal aid in the location of the fistula as well as the assessment of its architecture and compliance.Lower Endoscopy (Colonoscopy Or Sigmoidoscopy): The endoscope is placed through anus into the full or partial colon in this approach. It is used to evaluate and visualise the mucosal lining of the lower GI tract. It aids in the diagnosis of disorders such as rectal bleeding and cancer.
• Capsule enterography: It is a form of imaging technology that allows you to view into your GI system by swallowing a tiny camera device. This aids in the detection of parasite infestations, small intestinal bleeding varices, internal haemorrhoids, and intussceptions or hernias of the rectal column.
• Sclero therapy: It is a form of treatment that includes injecting sclerosant into the afflicted area of the hemorrhoidal condition and directly treating the internal haemorrhoids. This method is regarded as a more effective therapeutic approach for the treatment of piles, haemorrhoids, and other rectal problems.
• Trans rectal ultrasound: It is a type of diagnostic technique in which a probe is inserted into the rectal, the rectal column is examined, and a proper diagnostic image is created. This type of diagnostic technique is helpful in the treatment of fistula, haemorrhoids, which could be internal or external, as well as various forms of hernia.
• Endorectal MRI: It is the correct method for diagnosing any abnormalities in the rectal canal, including those related to vascular problems and muscle disorders, and it may be used to find out whether or not there are any. It is also a good technique for finding out prostate carcinoma.

• Incision and drainage: Serious skin infections (abscesses) in or around the anus may require this surgical procedure to drain the infected fluid.There is some sort of chronic skin infection and formation of Abscess or pus or any security fluid is found then surgical procedure is required to drain out the infected fluid which helps in increasing the symptoms and treatment of the infection.
• Lateral internal sphincterotomy: surgical procedure required to reduce the pressure in the anal canal which is helpful in also dealing with tear and any sort of injury to the anal canal it is known for treating anal fissures.
• Fistulotomy: it is a surgical procedure in which unwanted canals formed in the inner region because of hemorrhoids and chronic infections called as fistula are are treated which includes delineation of the fistula tract and draining any undrained Abscess is involved with the canal of fistula.
• Setone: because of chronic Abscess formation in the fistula seton placement is done by surgeon to prevent and treat the fistula. It is a type of surgical thread which is placed in the crystal or canal of the fistula.
• Lords procedure: Because of increased pressure in the anal canal several conditions like hemorrhoids and fistula can be created add to treat this inner dictation is performed which is called as Lords procedure And after dilatation hemorrhoidectomy is performed.
• Anal advancement flap: for the treatment of anal fistula and Anal fissure anal advancement flap is used. It is the best surgical method for treating these conditions. it is also considered sprinter preserving procedure which can be considered a good prognosis.
• Miles Procedure: for the treatment of rectal cancer the abdominoperineal resection of the rectum and abdominoperineal excision of the rectum is a surgery which is preferred since 20 years.
• Surgical hemorrhoidectomy: Surgical procedure in which removal of one or more number of hemorrhoids which can be connected to each other or can be found separately in different parts of anal canal.
• Rectal tube placement: Because of decreased mobility of the large intestine and increased number of gases in the rectal canal our rectal tube is placed along with sigmoidoscope to decrease pressure and release the gases present in the rectal canal.
• Colonoscopic decompression: And there is a case of low GI motility decompression is done which involves placing a scope into the intestine and exchange of gases is done by the help of this tube which involves section of external and internal gases found in the gut which can either be formed by any sort of parasitic infestation or formed by the digestion of the food.
• Hemorrhoid banding: Surgical rubber bands are tied around the external and internal hemorrhoids which decreases the vascular exchange between the issues and the hemorrhoids then wither off after a certain period of time

• Steroid cream for anal irritation: pitching over the anal canal and at the end of the anus can be resolved by using steroidal cream having combinations with antifungal and antibiotics which are helpful in treating the problem. some of the examples include combination of betamethasone with amoxicillin or combination of neomycin with clotrimazole
• Chloride Channel Activator for redcuing load on rectal column: Lubiprostone is part of the clinical category known as chloride channel activators. This is accomplished by boosting the amount of fluid that is already present in your intestines, which, in turn, makes it easier for faeces to go through your digestive tract.
• Anti-Diarrheal Agent for reducing rectal inflammation: Loperamide is also used for chronic or recurrent diarrhoea caused by bowel diseases such as Crohn's disease, ulcerative colitis, or short bowel syndrome. This kind of diarrhoea may linger for weeks or months. Additionally, cholestyramine is used.
• Prebiotics for maintaining flora of rectum: In the therapeutic treatment, they are used to boost the activity of beneficial bacteria in the gut, which allows for a more stable pH level in the gut to be maintained as required.
• Probiotics for maintaining flora of rectum: They are beneficial to the ecosystem of the gut and provide beneficial microorganisms such as Bifidobacterium and Lactobacillus.
• Antibiotics for rectal inflammation: Antibiotics, in combination with other treatments, may be used to treat an infection caused by H. pylori. During treatment, the antibiotics are given to the stomach in an effort to heal the damage caused by the infection. and also Amox-Clavulanate given for diverticulitis.
• Antiparasitic drugs for trichonomiaisis: In the treatment of parasites, some examples include metronidazole, praziquantel, and albendazole. In the treatment of bacterial infections, some examples include azithromycin, ciprofloxacin, and tetracycline.
• Antiviral Medications: A number of antiviral drugs, such as entecavir, tenofovir , lamivudine , adefovir , and telbivudine, can aid in the fight against the virus and lessen its ability to harm your rectal colum which could getinfection because of STDs and other gi infections.
• Diuretics: Conditions other than edema that lead to fluid retention are also treated with these drugs, including cirrhosis and hypertension. Numerous medical professionals prescribe diuretics such aldactone, bumetanide, torsemide, hydrochlorothiazide, furosemide, and metolazone to reduce ascites and abdominal fluid accumulation at the time of infection.
• Chemotherapeutic Drugs for rectal carcinoma: Chemotherapy and radiation are effective treatments for liver cancer, despite the disease's untreatable nature. In extreme cases, the liver may be removed surgically or replaced with a donor organ.
• Corticosteroids for haemorrhoids and rectal prolapse: Drugs with anti-inflammatory properties work by preventing the recruitment of polymorphonuclear leukocytes (PMNs) to areas of cellular and tissue injury, hence reducing inflammation. Methylprednisolone is an example of an effective corticosteroid.
• Nifedipine or Nitroglycerine given for rectal prolapse: it acts as a vasodilator and helps in treating the irritation of anal canal also helps in reducing pain when there is a situation of rectal prolapse after prolonged Constipation or irritation of rectum