Boundaries of abdomen,peritoneum,lesser sac,foramen of winslow Dr.Suhasini p.tayde Associate professor Department of anatomy Boundaries of abdomen Abdomen- part of trunk extending from thoracic diaphragm to the pelvic diaphragm It consist of two parts abdomen proper and lesser pelvis Boundaries Lower part of thoracic cage forms the upper part of anterior abdominal wall Laterally the wall consist of three flat muscles Diaphragm is the superior boundary Posterior wall is formed by lumbarvertebrae,diaphragmatic crurae,psoas major,quadratus lumborum Clinical imp-overlapping of the upper abdominal cavity by lower thorax has clinical importancs as penetrating wounds of lower thorax may injure the abdominal viscera Peritoneum It is a thin, serous, continuous glistening membrane lining the abdominal & pelvic walls and clothing the abdominal and pelvic viscera. Parietal layer lines the wall & visceral layer covers the organs. The potential space between the two layers is filled with very thin film of serous fluid to facilitate the movement of the abdominal organs. Peritoneal cavity is the largest cavity in the body. Subdivisions of the peritoneal cavity It is divided into two main sacs: 1- Greater sac. 2- Lesser sac or omental bursa. These two sacs are interconnected by a single oval opening called the epiploic foramen or opening into lesser sac or foramen of Winslow Greater sac is further divided into supracolic and infracolic compartments Supracolic compartment-it occupies upper anterior part of abdominal cavity Infracolic space-entire abdominopelvic cavity below tranverse colon Intraperitoneal And Retroperitoneal Relationships Intraperitoneal organ means that the organ is completely covered by visceral layer of peritoneum e.g. stomach, jejunum, ileum & spleen. Retroperitoneal organ means that the organ lies behind the peritoneum and partially covered by visceral peritoneum e.g. pancreas, ascending & descending colon. Lesser sac = omental bursa Deep to lesser omentum Behind the stomach Between two layers of greater omentum Under the diaphragm and liver Deep to lesser opening (Epiploic opening) Lesser sac or omental bursa Is a recess that lies behind stomach & lesser omentum and the posterior surface of stomach It projects upwards as far as the diaphragm. Inferiorly it lies within the folding of the greater omentum. Its lower part is usually obliterated due to fusion of the anterior & post layers of the greater omentum. It communicates with greater sac only through the epiploic foramen. it is called omental bursa because it act as a bursa for the stomach allowing for its expansion and mobility Anterior wall: from above downward lesser omentum, back of stomach & anterior 2 layers of greater omentum. Posterior wall: From below upwards, posterior 2 layers of greater omentum, then the peritoneum which covers many structures on posterior abdominal wall These structures are: 1- Body of pancreas. 2- Part of abdominal aorta 3- Coeliac artery & its branches (splenic, Leftt gastric & hepatic arteries) Lower margin is the line of continuity of the two anterior layers of greater omentum with its two posterior layer Left margin is formed by left margin of greater omentum and linorenal and gastroslenic ligament Right margin formed by right margin of greater omentum and by reflection of peritoneum from pancreas to the posterior aspect of duodenum Lesser sac is divided into five parts vestibule Body and three recesses superior,splenic and inferior . Epiploic foramen Omental (epiploic)foramen Position: - lies between the liver and duodenum at the level of T12 vertebra - just above the first part of the duodenum - behind the lesser omentum - infront of the inferior vena cava Epiploic foramen The omental bursa (lesser sac) communicates with the greater sac through the omental foramen. Epiploic foramen Boundaries Anteriorlly - Free border of lesser omentum contain 1- Bile duct 2- Hepatic artery 3- Portal vein(post.) Posteriorly I.V.C Superiorly Caudate process of caudate lobe of liver Inferiorly First part of duodenum Applied anatomy Internal herniation ,a loop of intestine herniates through epiploic foramen into the omental bursa In perforation of gastric ulcer there is collection of inflammatory fluid in the omental bursa.