====== RECTUM ====== * RECTUM * FEATURES * place between * sigmoid canal and anus * distension * desire to defecate * shape * not straight * curved anteroposterior direction * absent * sacculations , appendices epiploicae , taenia * SITUATION * posterior part of pelvis * infront of 3 pieces of sacrum * EXTENT * begins at * level of S3 vertebra * from recto-sigmoid junction * ends at * ano-rectal junction * a little below the tip of coccyx * DIMENSIONS * 12 cm long * upper part * 4 cm diameter same as sigmoid colon * lower part * dilated to form rectal ampulla * COURSE AND DIRECTION * runs * downward and backward * downward * downward and forwards * curvatures * anteroposterior curves * sacral flexure of rectum * follows concavity of sacrum and coccyx * perineal flexure of rectum * backward bend at anorectal junction * lateral curves * upper lateral curve * convex to the right * middle lateral curve * convex to left and most prominent * lower lateral curve * convex to right * RELATIONS * Peritoneal relations * upper 1/3rd covered with peritoneum * infront * sides * middle 1/3 * only infront * lower 1/3 * devoid of peritoneum * lies below * rectovesical pouch in males * rectouterine pouch in females * Visceral relations * anteriorly * in males * upper 1/3 is related to * rectovesical pouch * with coils of intestine and sigmoid colon * lower 1/3 * base of urinary bladder , terminal parts of ureters * seminal vesicle , deferens ducts and prostrate * in females * upper 1/3 is related to * rectouterine pouch * with coils of intestine and sigmoid colon * lower 1/3rd * lower part of vagina * posteriorly * same in male and female * lower 3 pieces of sacrum , coccyx , anococcygeal ligament * piriformis , coccygeus and levator ani * median sacral , superior rectal and lower lateral sacral vessels * sympathetic chain and ganglion impar * pelvic splanchnic nerves * anterior primary rami of s3,s4,s5 * MUCOSAL FOLDS * longitudinal folds * transitory * transverse folds or houston's valves or plicae transversales * permanent * types * first tranverse fold * upper end of rectum * second transverse fold * upper end of rectal ampulla * third transverse fold * projects from left wall * FUNCTIONAL PARTS OF RECTUM * sigmoid colon is the faecal reservoir * rectum is a temporary reservoir * Arterial supply * superior rectal artery * Middle rectal artery * Median Sacral artery * Venous supply * Superior rectal vein * Middle rectal vein * Median sacral vein * Lymphatic drainage * Upper half of rectum * along superior rectal vessels to inferior mesenteric nodes * through pararectal and sigmoid nodes * Lower half of rectum * Middle rectal vessels to internal iliac nodes * Nerve supply * Supports of rectum * Pelvic floor formed by levator ani muscles * fascia of waldeyer * lateral ligament of rectum * rectovesical fascia of denonvilliers * Pelvic peritoneum * Perineal body with its muscles * Sacral flexure * Lateral flexures * Superodextral lateral flexure; superior lateral flexure * Intermediosinistral lateral flexure; intermediate lateral flexure * Inferodextral lateral flexure; inferior lateral flexure * Transverse folds of rectum [[Kohlrauschi]] * Rectal ampulla * Muscular layer; muscular coat * Longitudinal layer * Rectococcygeus * Anorectoperineal muscles; recto-urethral muscles * Rectoperinealis; recto-urethralis superior * Anoperinealis; recto-urethralis inferior * Rectovesicalis * Circular layer * Lateral ligament of rectum; rectal stalk {{:anatomy:rectum-relations.png}} {{:anatomy:rectum-topography.png}} {{:anatomy:rectum.png}}