GIT 2025 Anatomy Lecture (PDF)

GIT 2025 Anatomy Lecture(2): PERITONEUM - Thin, serous, continuous glistening membrane lining the abdominal & pelvic walls and clothing the abdominal and pelvic viscera. - Parietal layer lines...

GIT 2025 Anatomy Lecture(2): PERITONEUM - 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. - The surface area of parietal & visceral layers is enormous. The relationship between viscera and peritoneum - Intraperitoneal viscera: viscera completely surrounded by peritoneum, example, stomach, superior part of duodenum, jejunum, ileum, cecum, vermiform appendix, transverse and sigmoid colons, spleen and ovary - Interperitoneal viscera: most part of viscera surrounded by peritoneum, example, liver, gallbladder, ascending and descending colon, upper part of rectum, urinary bladder and uterus - Retroperitoneal viscera: some organs lie on the posterior abdominal wall and are covered by peritoneum on their anterior surfaces only, example, kidney, suprarenal gland, pancreas, descending and horizontal parts of duodenum, middle and lower parts of rectum, and ureter 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 7  GIT 2025 Anatomy Lesser sac Definition: large peritoneal sac situated behind lesser omentum and stomach Walls: - Superior: peritoneum which covers caudate lobe of liver and diaphragm. - Anterior: formed by lesser omentum, peritoneum of posterior wall of stomach and anterior 2 layers of greater omentum. - Inferior: closed by folding of greater omentum on itself - Posterior: formed by posterior 2 layers of greater omentum, transverse colon and transverse mesocolon, peritoneum covering pancreas. - Left: formed by spleen, gastrosplenic ligament and splenorenal ligament. - Right: formed by omental foramen. Greater sac The transverse colon and transverse mesocolon divides the greater sac into supracolic and infracolic compartments Supracolic compartments Infracolic compartments - Site: - lies between －lies below transverse diaphragm and transverse colon colon and transverse and transverse mesocolon. mesocolon - Parts: - The falciform - The mesentry of small ligament divides it into right and intestine divide it into upper left parts. RT region and lower LT region. Contents: - Its contents are: (subphrenic spaces) - its contents are: (paracolic Left subphrenic spaces: gutters) - left anterior subphrenic space. Right paracolic gutter 8 GIT 2025 Anatomy - left posterior subphrenic space - Right lateral paracolic (lesser sac). gutter. Right subphrenic spaces - Right medial paracolic - Right anterior subphrenic gutter. space(bare area of liver) left paracolic gutter - Right posterior subphrenic - Left lateral paracolic space. gutter. Extraperitoneal spaces: - Left medial paracolic - Right extraperitoneal space. gutter - left extraperitoneal space. Epiploic Foramen Boundaries Anterior: free margin of lesser omentum, containing (hepatic artery, bile duct and portal vein) Posterior: peritoneum covering IVC. Superior: Caudate process of the caudate lobe of the liver. Inferior: 1st inch of the1st part of duodenum. Peritoneal folds Definition: Double layers of peritoneum that connect organ to organ or organ to abdominal wall, they are of 3types: 1- Omenta: connect the stomach to other organs, they are: A- Greater omentum. B- Lesser omentum. 2- Mesenteries: connect intestine to post. Abdominal wall, they are: A- Mesentery of small intestine. B- Transverse mesocolon. C- Sigmoid mesocolon. D- mesoappendix. 3- Ligaments: connect organ to organ or organ to abdominal wall, they are: 9 GIT 2025 Anatomy A- gastrosplenic ligament. B- lienorenal ligament. C- falciform ligament. Greater Omentum Definition: largest peritoneal fold connecting stomach to transverse colon. - It formed of 4 layers 2 anterior and 2 posterior. - It hangs down like an apron in front of coils of small intestine Attachments: -The anterior 2 layers: attach to greater curvature of stomach and descends a variable distance into the peritoneal cavity and then turns sharply on itself to ascend as the posterior 2 layers. -The posterior 2 layers: passes anterior to transverse colon and transverse mesocolon. It end by attachment to anterior border of body of pancreas. Contents: - Right and left gastroepiploic vessels. - Right gastroepiploic LN and lymphatics. Lessor omentum (gastrohepatic ligament) Definition: 2 layers of peritoneum, runs from inferior visceral surface of the liver to the abdominal oesophagus, stomach, and first part of duodenum. Attachment: - Superiorly (hepatic attachment): forms an L-shape, the vertical component of the L is formed by the fissure for ligamentum venosum and the horizontal limb to the lips of porta hepatis. 10 GIT 2025 Anatomy - Inferiorly (gastric attachment): attached to lesser curvatures of stomach and 1 st inch of the duodenum. To form gastrohepatic and hepatoduodenal ligaments, respectively. - RT free border: from porta hepatis to 1st inch of the duodenum and form the anterior boundary of lesser omentum. - Upper border (diaphragmatic): attached to the under surface of diaphragm. Contents: 1- in the right lateral border: it forms the anterior wall of the epiploic foramen. It contains the portal vein, common bile duct, and hepatic artery. 2- along the gastric border: it contains RT and LT gastric vessels, branches of the vagus nerves, and gastrohepatic lymph nodes 3- between the 2 layers: it contains LN and lymphatics and the hepatic plexus of nerves. 11