GIHEP 02 General Arrangement of the Abdomen 2023 PDF

General arrangement of the abdomen Gastrointestinal tract Dr Sara Sulaiman [email protected] Learning outcomes By the end of this lecture, you should be able to: Outline the location and arrangement of the major abdominal organs Explain how the peritoneum is arranged within the abdomen,...

General arrangement of the abdomen Gastrointestinal tract Dr Sara Sulaiman [email protected] Learning outcomes By the end of this lecture, you should be able to: Outline the location and arrangement of the major abdominal organs Explain how the peritoneum is arranged within the abdomen, with parietal and visceral layers Describe how the peritoneum is reflected from the wall to viscera to form peritoneal attachments or ligaments Describe how the dorsal and ventral mesogastria are formed with the rotation of the stomach Explain the main abdominal compartments and recesses, and why these are clinically relevant Recommended reading Abrahams, Peter H. et al. McMinn & Abrahams’ Clinical Atlas of Human Anatomy. Seventh edition. Maryland Heights, Missouri: Elsevier Mosby, 2013. PrintDrake, Richard L. Gray’s Anatomy For Students. 4th. ed. Philadelphia: Elsevier, Inc., 2020. Print. Moore, Keith L., Arthur F. Dalley, and A. M. R. Agur. Essential Clinical Anatomy. 4th ed. Philadelphia, Pa.; London: Lippincott Williams & Wilkins, 2011. Print. Netter, Frank H. (Frank Henry). Atlas of Human Anatomy. 5th ed. Philadelphia, Pa.; London: Saunders, 2010. Print. Smith, C., Dilley, A., Mitchell, B. and Drake, R.L., 2017. Gray’s Surface Anatomy and Ultrasound: Gray’s Surface Anatomy and Ultrasound E-Book. Elsevier Health Sciences. Spratt, J., Salkowski, L.R., Loukas, M., Turmezei, T., Weir, J. and Abrahams, P.H., 2020. Weir & Abrahams' Imaging Atlas of Human Anatomy. Elsevier Health Sciences.  Abdominal regions Can you list the organs located in each quadrant? Four-Quadrant Topographical Pattern Nine-Quadrant Topographical Pattern  What is the surface landmark of the Subcostal vs L1 planes subcostal plane? Transpyloric plane passes through L1. It crosses: The pyloric orifice 1st part of the duodenum The body of the pancreas Fundus of the gallbladder Hila of the kidneys Hilum of the spleen The end of the spinal cord Origin of superior mesenteric artery Left and right colic flexure How does the abdomen look like?  General arrangement of the gut tube** Abdominal aorta Blood supply Lymphatics Parasympathetics Sympathetic Foregut Celiac Trunk (lower level of Greater splanchnic Abdominal T12) nerves oesophagus to (T5-T9) synapsing the midpoint of Celiac nodes Vagus nerve Splenic vein* at celiac ganglia the duodenum Superior Superior Vagus nerve Lesser splanchnic Midgut mesenteric a. mesenteric nodes nerves (at L1) Midpoint of the (T10-11) synapsing duodenum to at the superior the distal third of Superior mesenteric ganglia the transverse mesenteric vein* colon Inferior mesenteric a. Inferior Pelvic splanchnic Lumbar splanchnic (at L3) mesenteric nodes nerves (L1-2) nerves Hindgut (S2-4) synapsing at the Distal third of inferior mesenteric Inferior ganglia the transverse mesenteric vein* colon to the rectum *Veins are not shown in the image **This is the general arrangement, details/exceptions will be added in coming lectures  Peritoneal cavity Permit movement of intestines during digestion independent of movement of the body wall Parietal Peritoneum: a thin membrane that lines peritoneum the wall of the abdominal cavity and Visceral viscera. Consist of two continuous peritoneum layers: Parietal: lines the wall (well- localised pain-innervation: somatic nerves) Visceral: lines the organs (diffused pain-innervation: autonomics) § Pain referred to dermatomes What innervates each layer of the peritoneum? Why is this important clinically? Peritoneal cavity Peritoneal cavity: a potential space between the parietal and visceral peritoneal layers. Greater sac: Parietal Most of the peritoneal cavity peritoneum Begins superiorly at the Visceral diaphragm and continues peritoneum Lesser sac inferiorly into the pelvic cavity Lesser sac: Greater sac An area behind the stomach and liver connected to the greater sac by the epiploic foramen Extends up and down to a varying degree Omental (epiploic) foramen Lesser sac  What does Organs can be divided based on their extraperitoneal, subperitoneal, relationship to the peritoneum: preperitoneal mean? Intraperitoneal: covered completely by peritoneum- Stomach, liver, gall bladder, spleen, jejunum, ileum, transverse colon, sigmoid colon, uterus, and ovaries. Intraperitoneal organ Retroperitoneal: Primarily retroperitoneal: organs developed and remain outside of the parietal peritoneum-kidneys, Mesentery suprarenal glands, aorta, inferior vena cava, urinary bladder, prostate, vagina, and rectum. Visceral peritoneum Parietal Secondarily retroperitoneal: organs were initially peritoneum intraperitoneal, suspended by mesentery, but as they develop, their mesentery fuse with the posterior abdominal wall. Only their anterior surface is covered with peritoneum- pancreas, duodenum, ascending and descending colon. Retroperitoneal structures-THINK: SAD PUCKER: Suprarenal(adrenal) glands, Aorta (&IVC), Duodenum (except the proximal 2cm, the duodenal Retroperitoneal cap), Pancreas (except the tail), Ureters, Colon (ascending and organ descending parts), Kidneys, E(O)sophagus, Rectum  Greater omentum Transverse mesocolon Peritoneal folds Small intestine Mesentery: Double layers of peritoneum. mesentery Connects the organs to the posterior (cut) abdominal wall and acts as means for Sigmoid Lesser neurovascular structures to reach the organs. mesocolon curvature of the stomach Omentum: double layer of peritoneum spanning between organs. Greater omentum: four-layered peritoneal fold. It descends from the greater curvature of the stomach, folds back and attaches to the transverse colon. Known as the “abdominal policeman” Lesser omentum: connects the lesser curvature of Lesser omentum the stomach and the first part of the duodenum to Hepatoduodenal the liver. ligament Hepatogastric Peritoneal ligaments: double layer of ligament peritoneum that connects an organ to Greater curvature of another organ or the abdominal wall. Greater omentum the stomach  Peritoneal ligaments Falciform ligament Hepatogastric ligament Gastrophernic The liver is connected to: ligament The abdominal wall by the falciform ligament. Stomach by the hepatogastric ligament (part Gastrosplenic ligament of the lesser omentum) Duodenum by the hepatoduodenal ligament (part of the lesser omentum) Hepatoduodenal The stomach is connected to: ligament Inferior surface of the diaphragm by the containing the portal triad gastrophernic ligament Spleen by the gastrosplenic ligament Gastrocolic ligament Transverse colon by the gastrocolic ligament (part of the greater omentum) What is the portal triad? What structures can be found in the free margin of the lesser Peritoneal ligaments The spleen is attached to various organs by: Gastrosplenic Gastrosplenic ligament ligament (contains the short gastric Splenorenal vessels and left ligament gastro-omental vessels) Splenic vessels Short gastric Splenorenal ligament vessels (contains the splenic vessels and the tail of the pancreas) Peritoneal Hepatoduodenal ligament containing ligaments the portal triad Falciform Hepatogastric Lesser ligament ligament omentum Gastrosplenic ligament Greater sac Liver stomach Greater sac Omental (epiploic) foramen Splenorenal Lesser sac (lienorenal) ligament Subdivisions of the peritoneal cavity Transverse mesocolon divides the Supracolic cavity into: compartment Supracolic compartment: liver, stomach, spleen Infracolic compartment: small intestine, ascending and descending Infracolic colons (located posterior to the compartment Transverse Transverse greater omentum). mesocolon mesocolon Free communication of fluid occurs through paracolic gutters (run along the lateral edge of the ascending/descending colons).  Liver Stomach 2 Greater omentum 1 3 Gravity dependent areas Free peritoneal fluid will accumulate in the deepest areas: In the upright position: to the rectovesical pouch (males) or rectouterine pouch (females) In supine position: to the hepatorenal recess (of Morison’s) (mainly) Peritonitis When bacteria enter the gut (trauma, infection, inflammation), it can result in an inflammation of the peritoneum (peritonitis). Patients would present with severe abdominal pain in the overlaying skin and an increased tone of the anterolateral muscles. If generalized, then it can be a dangerous condition. The patient will present with vomiting, fever, constipation, nausea and tenderness. Ascites Unusual collection of fluid in the peritoneal cavity. Can be caused by several conditions. Can be several liters of fluid. Case courtesy of David Cuete, Radiopaedia.org, rID: 23057 Development During development, the gut tube is suspended by a dorsal mesentery. The dorsal mesentery related to the stomach is known as the dorsal mesogastrium and elongates considerably as the greater omentum. The spleen develops in the dorsal mesogastrium The caudal part of the foregut develops the ventral mesentery. The liver develops in the ventral mesentery  Stomach develops from a cylindrical tube, then the posterior wall grows faster than the anterior wall. It undergoes 90 rotation clockwise. Dorsal mesogastrium is pulled to the left side The small compartment lying between the stomach and the dorsal wall of the embryo develops as the lesser sac of the peritoneal cavity. The liver enlarges to the right, pulling the ventral mesogastrium with it: The portion between the liver and the ventral wall of the embryo becomes the falciform ligament. The portion between the stomach and liver becomes the lesser omentum. Leading the world to better health