Inferior rectal artery (branch of the internal pudendal artery ).Superior rectal artery (branch of the inferior mesenteric artery).Stratified nonkeratinized squamous epithelium (known as anal pecten).Innervated by the enteric nervous systemĬharacteristics of the anal canal above and below the dentate line.
Anal sinuses: small, mucus-secreting pouches between the anal columns above the anal valves.Anal columns: longitudinal folds of mucous membrane that are fused at their inferior ends by transverse folds ( anal valves).Defecation causes contraction of supportive structures (e.g., Treitz muscle) → compression of anal cushions → increased diameter of the anal canal for adequate passage of stool.Play an important role in maintaining continence by enabling tight closure of the rectum.Located at 11, 7 and 3 o'clock in the lithotomy position (right anterior, right posterior, and left lateral position).Areas of thickened anal mucosa that consist of arteriovenous blood vessels ( corpus cavernosum recti), smooth muscle (e.g., Treitz muscle), and fibroelastic tissue (e.g., collagen, elastic fibers).Those who present later should be managed conservatively. Surgical excision of the thrombosed hemorrhoid may be beneficial in patients who present within 3–4 days of symptom onset. Thrombosed external hemorrhoids manifest with acute pain and a tender bluish-purple perianal nodule. Hemorrhoids refractory to medical management and larger ( grades III and IV) internal hemorrhoids typically require procedures such as rubber band ligation, sclerotherapy, and infrared coagulation, or surgery. Medical management also includes stool softeners and short-term use of topical medications (e.g., anesthetics, corticosteroids, or vasoconstrictors) for symptomatic relief. All patients with symptomatic hemorrhoids should be counseled on lifestyle modifications (e.g., increased fiber and fluid intake, regular physical activity) to reduce straining during defecation. Further investigation with proctoscopy, sigmoidoscopy, or colonoscopy may be required to rule out differential diagnoses of hemorrhoids, including colorectal cancer. The diagnosis is primarily clinical, based on a thorough history and examination that includes a digital rectal examination and anoscopy. Internal hemorrhoids are classified into four grades according to the extent of prolapse. Based on their anatomical location, hemorrhoids are internal ( above the dentate line), external ( below the dentate line), or mixed. Excessive straining during defecation or intraabdominal pressure (e.g., due to constipation, pregnancy, or prolonged periods sitting) increase the likelihood of developing hemorrhoids. Hemorrhoids are dilated submucosal vascular cushions within the anal canal that can be asymptomatic or manifest as painless perianal masses, pruritus, or intermittent scant hematochezia ( bright red blood per rectum, typically at the end of defecation).