Mesenteries and Ligaments

Mesenteries and Ligaments Key Information • The mesenteries (connecting roots) are double layers of visceral peritoneum that connect abdominal organs to the posterior abdominal wall. • Embedded within are blood vessels and relevant structures. • Vessels, nerves, and lymphatics of intraperitoneal structures are distributed to their respective organs in mesenteries. • The peritoneal ligaments are double layers of peritoneum that connect organs to each other. Structure of the mesentery • • Mesentery Proper: From the jejunum and ileum to the posterior abdominal wall (contain superior mesenteric artery, autonomic nerve plexuses, lymphatics, and fat) Transverse mesocolon: Transverse colon to posterior abdominal wall (middle colic artery) - Divides the abdominal cavity into a superacolic compartment (contains the stomach, liver and spleen) and infracolic compartment (contains small intestines, ascending and descending colon) • • Sigmoid mesocolon: sigmoid colon to the pelvic wall (sigmoid arteries, superior rectal artery) Mesoappendix: mesentery of ileum to appendix (appendicular artery) Ventral Mesogastrium • Ventral mesentery of the embryonic cavity that persists as the falciform ligament and the lesser omentum - the ventral mesentery extends between the future stomach and proximal duodenum and anterior abdominal wall superior to the umbilicus (umbilical vein) - the liver develops within it, consequently the lesser omentum, coronary, falciform ligament are derived from it. • Lesser omentum - Connects the stomach to the liver ✓ Attached to the small curvature of the stomach to the live r - Formed by hepatogastric and hepatoduodenal ligaments ✓ Hepatogastric ligament: proximal portion of the lesser omentum ✓ Hepatoduodenal ligament: portion of the lesser omentum extending between the porta hepatis of the liver and the superior part of the duodenum - Forms anterior border of the epiploic foramen - Omental foramen is opening to omental bursa (lesser sac) r • Ligaments of the liver - Falciform: remnant of ventral mesentery of foetus - Ligamentum teres: round ligament of liver, remnant of umbilical vein) Dorsal Mesogastrium (anki from here onwards) • The part of the dorsal mesentery that attaches to the greater curvature of the stomach • The part that suspends at the colon is the mesocolon • Develops into the greater omentum • Has rich vascular supply • Hangs in a flap down the stomach and curves back up to connect to the transverse colon • Ligaments of the spleen: - Gastrosplenic ✓ Made of visceral peritoneum ✓ Connects the greater curvature of the stomach to the helium of the spleen - Splenorenal ✓ Represents dorsal part of the mesentery ✓ Forms the lateral border of the lesser sac ✓ Continuous with the gastrosplenic and phrenicocolic ligaments Omenta • Two layers of peritoneum • Fused peritoneal folds that connect the stomach and duodenum with other abdominal organs • Derived from embryological ventral and dorsal mesenteries Peritoneal folds • Portions of peritoneum that are uplifted from a wall by underlying vessels, ducts, or ligaments • On the posterior surface of the anterior abdominal wall five folds may be found • Serve as pathways for neurovascular structures to reach the organs from abdominal walls Fold Median umbilical fold Two Medial umbilical folds Two Lateral umbilical folds Description • Overlies median umbilical ligament • Extends from the apex of the urinary bladder to the umbilicus and covers the median umbilical ligament • Are lateral to median umbilical fold • Cover the medial umbilical ligaments (occluded umbilical arteries) • Lateral to the medial umbilical folds • Cover the inferior epigastric vessels