IMAGING ANATOMY OF PERITONEAL SPACES.pptx
- 1. IMAGING ANATOMY OF PERITONEAL SPACES Presenter A. Reshmasree Moderator _ DR. Kalaivaani
- 2. PERITONEUM: The peritoneum is a thin, translucent, serous membrane and is the largest and most complexly arranged serous membrane in the body. The peritoneum that lines the abdominal wall is called the parietal peritoneum, whereas the peritoneum that covers a viscus or an organ is called a visceral peritoneum. Both types of peritoneum consist of a single layer of simple low- cuboidal epithelium called a mesothelium. A capillary film of serous fluid (approximately 50100 mL) separates the parietal and visceral layers of peritoneum from one another and lubricates the peritoneal surfaces
- 3. PERITONEAL CAVITY: The peritoneal cavity is a potential space between the parietal peritoneum, which lines the abdominal wall, and the visceral peritoneum, which envelopes the abdominal organs. In men, the peritoneal cavity is closed. In women, it communicates with the extraperitoneal pelvis exteriorly through the fallopian tubes, uterus and vagina.
- 5. PERITONEAL LIGAMENTS: Peritoneal ligaments are double layers or folds of peritoneum that support a structure within the peritoneal cavity. Omentum: Mesentery or double layer of peritoneum that extends from the stomach and duodenal bulb to adjacent organs. The lesser omentum, which is made of two contiguous components called the gastrohepatic and hepatoduodenal ligaments, attaches the stomach and duodenal bulb to the liver. The greater omentum is attached to the stomach and hangs like an apron from the transverse colon.
- 6. Mesentery : a double layer of peritoneum that encloses an organ and connects it to the abdominal wall. The mesenteric contents include blood vessels, lymph nodes, nerves, and fat. The most mobile parts of the intestine have a mesentery (eg, the small bowel attached to the retroperitoneum), and the retroperitoneal portions of the colon may contain remnant mesocolon, a result of its failure to absorb embryonic mesentery.
- 8. EMBRYOLOGY: The primitive gut forms within the abdominal cavity and is suspended by a plane composed of two peritoneal reflections called the primitive mesenteries, which cover the extension of the subperitoneal space from the abdominal walls. The position of the gut within the primitive mesentery plane divides the primitive mesentery into ventral and dorsal portions, which undergo specialization throughout fetal life.
- 9. Vascular and lymphatic vessels and nerves that supply the abdominal viscera are enfolded within the plane of the primitive mesentery. The liver grows ventral from the gut within the ventral plane. The spleen and pancreas and a major portion of the gut grow within the dorsal plane.
- 12. SUSPENSORY LIGAMENTS OF LIVER Triangular Ligaments. Fusion of peritoneal reflections. The left triangular ligament is formed by the fusion of the inferior and superior reflections of the coronary ligaments. It is short and does not compartmentalize the left subphrenic space. The right triangular ligament is formed by the fusion of the superior and inferior reflections of the right coronary ligament. long and separates the right subphrenic space from the right subhepatic space. The triangular ligaments outline the bare area of the liver
- 13. Falciform Ligament. The remnant of the most ventral part of the ventral mesentery and contains the obliterated umbilical vein. It is a relative (incomplete) barrier to the transfer of fluid from the right subphrenic space to the left subphrenic space.
- 14. Peritoneal Ligaments of the Stomach Lesser Omentum .The gastrohepatic and hepatoduodenal ligaments are contiguous peritoneal ligaments that form the lesser omentum and are remnants of the dorsal portion of the ventral mesentery. The gastrohepatic ligament attaches the lesser curve of the stomach to the liver and contains the coronary vein and left gastric artery The hepatoduodenal ligament attaches the duodenum to the liver and contains the portal vein, hepatic artery, common hepatic ducts, and part of the cystic duct.
- 15. Until the 8th embryonic week, this part of the ventral mesentery also contains the ventral anlage of the pancreas. Hence, the hepatoduodenal ligament is a route of spread of pancreatic disease to the porta hepatis and liver
- 16. Gastrosplenic Ligament. The ventral part of the dorsal mesentery extends between the greater curve of the stomach and the spleen . The superior part of this portion of the dorsal mesentery becomes the gastrosplenic ligament, which contains the short gastric vessels and a collateral route of venous flow after splenic vein thrombosis. The gastrosplenic ligament is a frequent route for subperitoneal spread of pancreatitis-related fluid.
- 18. Greater Omentum. Because of the growth and rotation of the stomach in utero, the inferior aspect of the ventral part of the dorsal mesentery becomes redundant, and its two layers fuse with one another to form the gastrocolic ligament, or the greater omentum. The greater omentum may become visible if it is diseased or if ascites present.
- 20. Splenorenal Ligament. The splenorenal ligament is the most dorsal aspect of the dorsal mesentery. It contains the pancreatic tail and splenorenal collateral vessels in patients with portal hypertension
- 22. Transverse Mesocolon The transverse mesocolon is a peritoneal fold that attaches the transverse colon to the retroperitoneum and contains the middle colic vessels.
- 24. Small Bowel Mesentery The small bowel mesentery attaches the small bowel to the retroperitoneum and extends from the ligament of Treitz to the ileocecal valve. It contains the superior mesenteric vessels and their branches, which mark its position at contrast-enhanced CT. Among the peritoneal structures, the small bowel mesentery is one of the most likely to be involved by metastatic disease. Inflammation and tumor may involve the mesentery directly (eg, from the pancreatic body or jejunum) or by way of the neurovascular plexus or lymphatic channels that run within it.
- 25. Sigmoid Mesocolon The sigmoid mesocolon is a peritoneal ligament that attaches the sigmoid colon to the posterior pelvic wall and contains the hemorrhoidal and sigmoid vessels. The most common pathologic process involving this structure is acute diverticulitis. Perforated cancer and Crohn disease also may cause inflammation within the sigmoid mesocolon.
- 26. Peritoneal spaces The transverse mesocolon divides the peritoneum into the: supramesocolic and inframesocolic spaces paracolic pelvic spaces
- 28. Left Supramesocolic Spaces The left and right supramesocolic spaces usually communicate freely with one another and include the perihepatic, left subphrenic, and perisplenic spaces The phrenicocolic ligament is a relative but incomplete impediment to the spread of pathologic processes from the left paracolic gutter to the left subphrenic space
- 30. Right Supramesocolic Spaces The right supramesocolic spaces include the: right subphrenic (subdiaphragmatic) space, the Morison pouch (subhepatic or hepatorenal space), the lesser sac (omental bursa).
- 31. The right subphrenic space is separated from the left perihepatic space by the falciform ligament, which varies in size and may not always serve as a barrier to the spread of disease The right subhepatic space is an important site of fluid collections resulting from liver injuries because it is the most gravity-dependent space at this site.
- 33. lesser sac contains a superior recess (located above the peritoneal reflection of the left gastric artery) that is in close proximity to the caudate lobe and has a boomerang-shaped recess and a larger inferior recess that lies between the stomach and the pancreatic body. The superior and inferior recesses are separated by a peritoneal fold that accompanies the left gastric artery.
- 35. The inferior recess communicates with a potential space between the leaves of the greater omentum. On the right side, the inferior recess communicates with the subhepatic space through the foramen of Winslow. Thus, it is possible for bowel to herniate into the lesser sac through the foramen of Winslow
- 37. Right and Left Inframesocolic Spaces The right and left inframesocolic spaces are separated from the supramesocolic spaces by the transverse mesocolon and from the paracolic gutters laterally by the ascending or descending colon. The smaller right inframesocolic space is limited inferiorly by the attachment of the small bowel mesentery to the cecum; collections in this space generally do not extend into the pelvis. However, the larger left inframesocolic space communicates freely with the pelvis
- 39. Paracolic Spaces The paracolic spaces (gutters) are located lateral to the peritoneal reflections of the left and right sides of the colon . The right paracolic gutter is larger than the left and communicates freely with the right subphrenic space. The connection between the left paracolic gutter and the left subphrenic space is partially limited by the phrenicocolic ligament. Both the right and left paracolic gutters communicate with the pelvic spaces.
- 41. Pelvic Spaces In men, the most gravity-dependent site for fluid accumulation is the rectovesical space. In women, it is the retrouterine space (the pouch of Douglas) . Anteriorly, the medial umbilical folds, which contain the obliterated umbilical arteries, divide the pelvic spaces into lateral and medial compartments. On each side, the inferior epigastric artery divides the lateral pelvic compartments into lateral and medial inguinal fossae, the sites of direct and indirect inguinal hernias, respectively.