Transcript Slide 1
Abdomen – 1 Human Structure and Development 212 Week 6 – 2005 Avinash Bharadwaj Regions of Abdomen Descriptive convenience Landmarks used • Midclavicular lines (planes) • Transpyloric and transtubercular planes Variation in descriptions Epigastrium, umbilical, hypogastrium Two each – hypochondrium, lumbar, iliac Peritoneum Highly complex cavity, especially in the upper abdomen. Essential concepts • Visceral and parietal layers • Mesenteries (The mesentery, mesogastrium, mesocolon etc) • Retroperitoneal structures • Greater and lesser sacs Peritoneum Lesser sac Greater sac Greater omentum Lesser omentum The mesentery – Small intestine Mesocolon – Transverse + sigmoid Retroperitoneal Structures Organs which lose their mesentery • Secondarily retroperitoneal • Duodenum, pancreas, ascending colon, descending colon Organs which develop posterior to the cavity • Primarily retroperitoneal • Kidneys, adrenals GI Tract – General Plan Four layers • Mucosa • Lining epithelium + Lamina propria • Muscle layer – muscularis mucosae Submucosa • Main connective tissue layer • Major network of blood vessels • Network of nerves Muscularis externa • Smooth muscle • Inner circular • Outer longitudinal Serosa or adventitia Stomach Curvatures – variability in shape Parts • Fundus, body, pyloric antrum and canal • Functional divisions more important! Interior – rugae (Folds) Sphincters : “gate mechanisms” • Functional • Anatomical – thickening of circular muscle • What type are the sphincters of the stomach? Small Intestine Absorptive function • Large surface area • Circular folds of mucosa • Villi – projections of epithelium Duodenum • Largely retroperitoneal, C-shaped • Openings of bile and pancreatic ducts Jejunum and ileum • Long, with mesentery • Gradual transition • Thinner wall, smaller folds and villi, pattern of blood vessels Colon General features • Haustration • Taeniae coli – three bands of longitudinal muscle Caecum + appendix • Vermiform appendix • Importance and positions Ascending, transverse and descending parts • Location, peritoneal covering • Flexures – hepatic and splenic • Variability Pattern of Blood Vessels Three major arteries • Coeliac • Superior mesenteric • Inferior mesenteric Branches and anastomoses • Long channels parallel to gut tube • Short straight vessels Submucosa – rich network Liver Largest gland in the body Functions • Production of bile • Metabolic functions – carbohydrates, amino acids • Protein synthesis • Breakdown of haemoglobin • And many others…! Anatomical perspective Liver Receives venous blood from abdominal GIT • Portal vein Arterial blood supply – hepatic artery Hepatic veins – venous drainage to IVC Porta hepatis – the gateway • Hepatic artery, portal vein, bile ducts • One each from right and left ‘lobes’ • Functional lobes more important! • Anatomical lobes by landmarks Liver Peritoneal connections • Falciform ligament • Lesser omentum Diaphragmatic surface “Visceral” surface Details of relations not necessary Ligamentum teres • Obliterated umbilical vein • Umbilical vein – blood from the placenta Ligamentum venosum • Obliterated ductus venosus • Ductus venosus – shunt between portal vein and IVC Portal Vein IMV Splenic SMV + Splenic Portal vein Joined by smaller veins from stomach etc Portasystemic anastomoses Junctional regions • Oesophagus systemic veins to thorax, stomach portal vein • Anal canal (terminal part systemic) Other regions • “Bare area” of liver • Around the umbilicus • Around retroperitoneal organs Liver disease especially “cirrhosis” • Portal hypertension “varicosity”.