UNIVERSITY OF BABYLON HAMMURABI MEDICAL COLLEGE GASTROINTESTINAL TRACT S4-PHASE 1 2018-2019 Lect.2/session 3 Dr. Suhad KahduM Al-Sadoon F. I . B. M . S (S ur g. ) , M.B.Ch.B. [email protected] The Peritoneal Cavity & Disposition of the Viscera objectives u describe and recognise the general appearance and disposition of the major abdominal viscera • explain the peritoneal cavity and structure of the peritoneum • describe the surface anatomy of the abdominal wall and the markers of the abdominal viscera u describe the surface regions of the abdominal wall and the planes which define them § describe the structure and relations of : o supracolic and infracolic compartments o the greater and lesser omentum, transverse mesocolon o lesser and greater sac, the location of the subphrenic spaces (especially the right posterior subphrenic recess) The abdominal cavity The abdomen is the part of the trunk between the thorax and the pelvis. The abdominal wall encloses the abdominal cavity, containing the peritoneal cavity and housing Most of the organs (viscera) of the alimentary system and part of the urogenital system. The Abdomen --General Description u Abdominal viscera are either suspended in the peritoneal cavity by mesenteries or are positioned between the cavity and the musculoskeletal wall Peritoneal Cavity – Basic AnatoMical Concepts The abdominal viscera are contained either within a serous membrane– lined cavity called the Abdominopelvic cavity. The walls of the abdominopelvic cavity are lined by parietal peritoneum AbdoMinal viscera include : major components of the Gastrointestinal system(abdominal part of the oesophagus, stomach, small & large intestines, liver, pancreas and gall bladder), the spleen, components of the urinary system (kidneys & ureters),the suprarenal glands & major neurovascular structures. Peritoneal Cavity – Basic AnatoMical Concepts Anatomists refer to the peritoneal cavity as a “potential space,” since it normally contains only a small amount of serous fluid that lubricates its surface. Accommodates abdominal contents (Food, Faeces, Flatus, Fat & Fetus) in health. Accommodates abdominal contents in disease , fluid (ascitis, pus, blood), fluid in a cyst (ovarian cyst) & gas (hollow viscus perforation, carbon dioxide during abdominal surgery /exploration (laparoscopy /laparotomy. PeritoneuM The peritoneum is a glistening, transparent mesothelial serous membrane that consists of two continuous layers. u Parietal peritoneum. u visceral peritoneum. beneath the peritoneum areolar tissue contain a network of lymphatics and blood vessels from which all absorption and exudation must occur The abdominal cavity is lined by peritoneum, similar to pleura and serous pericardium in the thorax. The peritoneum is reflected off the abdominal wall to become a component of the mesenteries that suspend the viscera Where it is associated with the abdominal wall, it is referred to as parietal peritoneum Where it covers the organs, it is referred to as visceral peritoneuM. There are no organs in the peritoneal cavity???. u Parietal peritoneuM nerves v phrenic N v T7-L1 v pudendal N v obturator N v Lat. Femoral v cutaneus N AbdoMinal Viscera - intraperitoneal or extraperitoneal Intraperitoneal – structures suspended from the abdominal wall by mesenteries. Extraperitoneal – not suspended by mesenteries and lie between parietal peritoneum and the abdominal wall; described as being retroperitoneal in position During development, some structures (e.g. parts of the small & large intestines – 2 , 3& 4 part of duodenum, ascending & descending colon) are suspended initially by mesenteries but later become retroperitoneal secondarily by fusion of the part peritoneum with the abdominal wall. Knowledge of the development of the gastrointestinal tract is needed to understand the arrangement of abdominal viscera and mesenteries in the abdomen u Peritoneal Reflections Mesentery Partially retroperitneal Stomach PeritonealAscending & descending colon Ileum & Jejunum & Liver Tran s v e rs e & Reflections Sigmoid colon Pancreas Lower esophagus Retroperitoneal 2nd, 3rd & 4th parts of the duodenum The Abdomen – Surface Topography u Topographical divisions are used to describe the location of abdominal organs and the pain associated with abdominal disorders & disease Two schemes are most often used to divide the abdomen u into: u a nine-region pattern u a four-quadrant pattern Transpyloric plane (ofAddison). Midway between suprasternal notch and upper border of pubic symphysis. Intersect the L1 near its lower border & meet the tips of 9th costal cartilage where linea semilunaris cross the costal margin. On the Rt. Side it marks the position of fundus of gallbladder. Hilum of kidney. Origin of sup. Mesenteric art. Termination of spinal cord. Neck and adjacent body of pancreas. Confluence of sup. Mesenteric and splenic veins forming the portal vein. u Transtubercular (intertubercular) plane -pass through L5. - marks the origin of I.V.C The Disposition of the Viscera uSuperior poles of the kidneys are deep to the lower ribs u Viscera not under the domes of the diaphragm are supported and protected by the muscular walls of the abdomen Peritoneal Cavity Subdivided into the greater sac & lesser sac (also called (the omental bursa u Greater sac accounts for most of the space; the lesser sac is smaller & lies posterior to the stomach, communicates with the greater sac via entrance to the lesser sac (foramen of Winslow) Greater Sac & Lesser Sac A mesentery is a double layer of peritoneum The mesentery of the transverse colon (transverse mesolon) divides the peritoneal cavity into a supracolic compartment (containing the stomach, liver & spleen) and an infracolic compartment (containing Small intestine & ascending & descending colon) A mesentery connects an intraperitoneal organ to the body wall (usually the posterior abdominal wall Peritoneal Cavity – Clinical Co-relates u Large surface area facilitates spread of disease through the peritoneal cavity & over its contents u Allows infection & malignant disease to spread easily u Perforations of the gut tube will lead to rapid spread u Perforation of the bowel may allow gas to escape into the cavity; perforated gastric ulcer gas under the diaphragm OmentuM An omentum is a double-layered extension or fold of peritoneum that passes from the stoMach and proxiMal part of the duodenuM to adjacent organs in the abdoMinal cavity Greater OmentuM A prominent, four-layered peritoneal fold that hands down like an apron from the greater curve of the stomach. After descending it folds back and attaches to the anterior surface of the transverse colon and its mesentery. Lesser OmentuM A much smaller, double-layered peritoneal fold that connects the lesser curvature of the stomach and the proximal part of the duodenum to the liver. It also connects the stomach to the portal triad. u Peritonitis – infection & inflammation of the peritoneum due to bacterial contamination, traumatic penetration,bowelrupture. u Ascitis – excess fluid (mechanical injury, disorders such as portal hypertension, metastasis) leads to abdominal distension u Adhesions – result of stab wounds & infection – abnormal attachments between visceral peritoneum of adjacent viscera or between visceral peritoneum & parietal peritoneum ofabd. Wall Greater omentum forms adhesions to inflamed organs, seals off inflamed (organs (policeman of the abdomen Flow of Fluid in the Peritoneum u Infracolic spaces & Paracolic gutters determine the flow of fluid in the upright position & in the spread of infection Fluid flow into the pelvic cavity – fluid usually collects in the pelvic recesses - rectouterine pouch / rectovesicle recess. u Since absorption of toxins in the pelvic cavity is slow, patients with peritonitis are placed in the sitting position u In the supine position, fluid can spread or accumulate in the subphrenic recesses (spaces); subphrenic abscesses more common on the right side because of the frequency of ruptured appendices and duodenal ulcers u Perforations of the posterior wall of the stomach results in its fluid contents into the lesser sac.