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Colon Rectum Anal Canal. Sonal Tripathi. Large vs Small Intestines. Omental Appendices Teniae Coli Haustra Wider than small intestine.
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ColonRectum Anal Canal Sonal Tripathi
Large vs Small Intestines • Omental Appendices • Teniae Coli • Haustra • Wider than small intestine
Arterial Supply- Ileocolic branches of SMANerves- Superior mesenteric plexus Vagus nerve Sympathetic fibres from lower thoracic Afferent fibres of appendix accompany symp fibres to T10 Caecum Appendix Vermiform Contains masses of lymphoid tissue Arises from inferior to ileocecal junction Variable position (usually retrocecal) • First part • Lies in right iliac fossa, within 2.5cm of inguinal ligament • Blind intestinal pouch, no mesentery
Appendicitis • Severe pain in RIF • May begin in the periumbilical region...why? • Causes? • Examination • Pressure over Mc Burney’s point, why? • Complications • Ischaemia, gangrene, rupture of inflamed appendix => peritonitis • Treatment • Surgery (open or laparoscopic)
Colon • Ascending colon • Retroperitoneal • From caecum to R.lobe of liver (Hepatic flexure) • Transverse colon • Hepatic flexure to splenic flexure • Splenic flexure less mobile, anterior to inferior left kidney, attached to diaphragm via phrenicocolic ligament • Attached by mesocolon • Divides cavity into supracolic and infracolic compartments
Colon • Descending colon • Retroperitoneal • From splenic flexure to sigmoid • Passes anterior to lateral border of left kidney • Sigmoid colon • S-shaped loop, variable length • Links descending colon (iliac fossa) and rectum (S3 vertebra) • Rectosigmoid junction • Termination of taeniae coli • Long mesentery => volvulus • Left ureter and division of left common iliac artery • Retroperitoneal, posterior to root of sigmoid
Nerves and Vasculature • Ascending colon • SMA: ileocolic and right colic arteries • SMV: ileocolic and right colic veins • Superior mesenteric nerve plexus • Transverse colon • SMA: middle colic artery +/- R&L colic arteries • SMV • Superior mesenteric nerve plexus • Descending and sigmoid colon • IMA: left colic and sigmoid arteries • IMV => splenic vein => hepatic portal vein • Symp. Nerves: abdominopelvic splanchnic nerves, superior mesenteric plexus • Parasymp. Nerves: pelvic splanchnic nerves via pelvic plexus
Volvulus • Mobile ascending colon/ caecum • Sigmoid colon • Obstructive signs and symptoms • Constipation • Ischaemia • Faecal compaction • Necrosis • Complications • Perforation • Fatal peritonitis
Diverticulosis • Multiple out-pocketings of mucosa of colon • Middle aged/ elderly affected • Diverticular disease • Symptomatic diverticula • Diverticulitis • Inflammation of a diverticulum • Colonic diverticula • Mucosa protrudes through weak points between muscle fibres, where nutrient arteries perforate the muscle coat
Complications • Diverticulitis: altered bowel habit, left sided colic relieved by defecation/flatulence, pyrexia, tenderness • Perforation: ileus, peritonitis, shock • Haemmorhage • Fistulae: enterocolic, colovaginal, colovesical • Abscesses • Post-infective strictures
Colitis • Chronic inflammation of colon • Ulcerative: diffuse infl of the mucosa- can spread to entire colon- ulcer, polyp formation, diarrhoea with blood or mucous- anaemia • Crohn’s disease: can be from mouth to anus- spreads to entire thickness of tract- can have skip lesions- • Management • Medication • Surgical- colectomy +/- stoma
Rectum • Lies in the pelvis • From sigmoid colon (rectosigmoid junction S3) to anal canal (coccyx) • Flexures: • Sacral • Anorectal • Lateral (superior, inferior and intermediate) • Peritoneum reflections: • Males: rectum to posterior bladder => rectovesical pouch • Females: rectum to posterior vagina =>rectouterine pouch • Lateral, pararectal fossae- allow rectum to distend as fills with faeces
Anal Canal • Begins at end of rectum where puborectalis muscle narrows the ampulla • Internal/external anal sphincters • Pectinate line • Above: Visceral, columnar epithelium Anal columns • Below: Somatic, stratified sq. Epithelium, Anal valves and sinuses • Differences in blood and nerve supply
Nerves and Vasculature • Rectum and Anal Canal • Proximal part => IMA (superior rectal artery) • Middle and inferior => Internal iliac arteries (middle rectal arteries) • Anorectal junction and canal => Internal pudendal arteries (inferior rectal arteries)..below the pectinate • Arteries drain into the superior (portal venous), middle and inferior rectal veins (systemic venous) • Symp innervation: lumbar spinal cord • Lumbar splanchnic and hypogastric/pelvic plexuses • Parasymp: S2-S4 • Pelvic splanchnic and inferior hypogastric
Rectal Examination • Prostrate, seminal glands, cervix, sacrum, coccyx, ischial spines and tuberosities can be palpated among other things • Can also be used to look for malena and constipation • Colorectal Cancer • Bleeding, mucous, altered bowel habit • Surgical resection can be done depending on site of tumour • Ano-rectal varices • In portal hypertension at site of anastomoses between portal and systemic veins • Haemmorhoids • Dilations of submucosal veins bulging into lumen of canal • Internal: above pectinate line, can be ligated • External: painful as somatic supply, can prolapse into anus
Thanks for listening Questions?