Session 1B - Peritoneum and Peritoneal Cavity PDF

Session 1B Learning Outcomes 1. Identify the major organs within the abdominal cavity. 2. Describe the parietal and visceral peritoneum and the peritoneal cavity. Describe the innervation of the parietal and visceral peritoneum and its...

Session 1B Learning Outcomes 1. Identify the major organs within the abdominal cavity. 2. Describe the parietal and visceral peritoneum and the peritoneal cavity. Describe the innervation of the parietal and visceral peritoneum and its clinical significance. 3. Explain the terms ‘intraperitoneal’ and ‘retroperitoneal’ and give examples of intraperitoneal and retroperitoneal structures. 4. Understand the terms ‘mesentery’ and ‘omentum’. Understand their functions. Recommended Videos from Acland’s Video Atlas 5.5.2. The abdominal cavity, peritoneum (3:07). 5.2.4. Greater and lesser omentum (2:19). 5.2.5. Omentum: development (animation) (4:29) The Peritoneum and Peritoneal Cavity Session 1B 1  What is the peritoneum? A serous membrane that lines the abdominal wall and covers the organs within it What are the two layers of the peritoneum? Parietal and visceral Where is the parietal peritoneum? Lines the abdominal wall What innervates the parietal peritoneum? Somatic nerves that supply the overlying muscles and skin of the abdominal wall How is pain from the parietal peritoneum characterised? Session 1B 2  Sharp, severe, and well localised to the abdominal wall Where is visceral peritoneum? Adhered to the abdominal viscera (organs) What innervates the visceral peritoneum? Visceral sensory nerves How are ‘painful’ sensations conveyed back to the CNS from visceral peritoneum? Along the path of the sympathetic nerves that innervate the organ or structure it covers What are the characteristics of the pain from the visceral peritoneum? Dull and diffuse What separates the parietal and visceral peritoneum? Peritoneal cavity What is located within the peritoneal cavity? Thin film of peritoneal fluid What is the purpose of the fluid within the peritoneal cavity? Allows the viscera to slide freely alongside each other Are the two layers continuous with each other? Yes Session 1B 3  What does intraperitoneal mean? Almost completely covered by peritoneum e.g. stomach What does retroperitoneal mean? Posterior to the peritoneum, hence only covered by peritoneum on their anterior surface e.g. the pancreas and abdominal aorta Session 1B 4  Mesenteries and Omenta What are mesenteries and omenta composed of? Peritoneum What do mesenteries and omenta attach to? Organs What structures do mesenteries and omenta carry to the viscera? Blood vessels, nerves, and lymphatics. What do mesenteries and omenta contain in variable amounts? Fat (the greater omentum is very fatty) What are mesenteries? Folds of peritoneum that contain fat and suspend the small intestine and parts of the large intestine from the posterior abdominal wall Session 1B 5  What structures are embedded in the mesenteries? Arteries that supply the intestine (from the abdominal aorta) and veins that drain the gut (tributaries of the portal venous system) What are the greater and lesser omenta? Folds of peritoneum that are usually fatty and connect the stomach to other organs Where is the greater omentum? Hangs from the greater curvature of the stomach and rests on top of the small intestine What structure is embedded within the greater omentum? Transverse colon (part of the large intestine) Where is the lesser ometum? Session 1B 6  Attached to the lesser curvature of the stomach and connects the stomach and duodenum to the liver What is embedded within the lesser omentum? The hepatic artery, the hepatic portal vein and the bile duct Session 1B 7  Clinical Relevance Peritonitis What is peritonitis? Inflammation of the peritoneum What are the two types of peritonitis? Localised (i.e. to the region of peritoneum adjacent to an inflamed/infected organ) Generalised (affecting the whole peritoneum) What may cause peritonitis? Inflammation of an organ (e.g. the pancreas) or rupture of a hollow viscus (e.g. the stomach or bowel) How does rupture of the intestine lead to peritonitis? Allows faecal matter and bacteria to contaminate the peritoneum Session 1B 8  Why can peritonitis lead to sepsis? Because the peritoneum has a large surface area and is semi-permeable Peritoneal adhesions What is the purpose of the thin layer of peritoneal fluid in a healthy abdomen? Allows the abdominal viscera to slide freely alongside each other What are peritoneal adhesions? Pathological fibrous connections between the parietal and visceral peritoneum What leads to the formation of peritoneal adhesions? When the peritoneum is irritated (e.g. by infection) it produces fibrin, which causes the parietal and visceral peritoneum to adhere to each other What happens to peritoneal adhesions over time? They may become fibrous What are two potential complications of adhesions? Chronic abdominal pain and increased risk of the intestine becoming twisted or trapped. Session 1B 9  Ascites What is ascites? Increased volume of peritoneal fluid What causes ascites? Heart failure, liver failure or intra-abdominal malignancy What are the symptoms of ascites? Abdominal distension and discomfort. How can ascites be treated to relieve symptoms? By using an ascitic drain to remove the fluid, but fluid will usually reaccumulate Session 1B 10