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Lab Manual - Liver & Gallbladder |
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Assignments:
- Before lab:
- Download and review the Lab Overview PowerPoint.
- Review the Prelab Learning Module.
- Review the Steps of Dissection and Dissection Videos.
- During lab:
- Follow the steps of the dissection procedure in the Lab Manual (this page).
- Be certain to identify all of the Review Items.
- After lab:
- Read the Dissector Answers to cover the Learning Objectives for this lab.
- Read the Clinical Case for this lab.
- Review the Practice Questions for this lab.
Learning Objectives:
Upon completion of this session, the student will be able to:
- Trace the pathway of bile from the liver and gallbladder to the entry of the bile duct and pancreatic ducts into the 2nd part of the duodenum.
- Identify the parts of the liver and gallbladder and describe the relationships of their portal venous, hepatic arterial, and hepatic venous circulation.
- Identify the structures passing into and out of the porta hepatis and some of the most common variations on this pattern.
- Describe the surface anatomy and peritoneal relationships of the liver and gallbladder.
- Explain the discrepancy between the external lobulation of the liver and the true internal segmentation of the liver based on the branching of the intrahepatic arteries, veins, and ducts.
Procedure:
1. Examine the liver, gallbladder and biliary system, defining their peritoneal relations and parts. (Play movie; View images: N 229, 238, 242, 256, 265, 275, 286, 287A, 287B, 288, 289, 290, 291, 292, 294, 295, 300, 302, 305, 310, 312, 313, 317, 348, 349, 399, TG 5-02, 5-18, 5-19, 5-21A, 5-21B, 5-21C, 5-23, 5-24A, 5-24B, 5-24C, 5-25, 5-27, 5-28, 5-34, 5-35, 5-42)
Review the development of the ventral mesogastrium and determine the relationships of the liver within it. Define the falciform ligament, the coronary ligament and the right and left triangular ligaments. Review the relationship of the lesser omentum and its parts to the liver.
Observe the surface projection of the liver, its relation to the thorax, costal margin, diaphragm, lungs, heart, posterior body wall, and viscera of the abdominal cavity.
Consider the anterior body wall projection of the fundus, body and neck of the gallbladder and their peritoneal relations to the liver. Note the relationships to the first part of the duodenum and to the transverse colon. Strip the remaining peritoneum from the hepatoduodenal ligament. Locate the bile duct and trace to the porta hepatis. Identify the cystic duct, common hepatic and right and left hepatic ducts. Trace the proper hepatic artery toward the porta. Identify right and left hepatic arteries and the cystic artery. Note the relation of the right hepatic artery to the common hepatic duct. Variations are very common in this region; the most common pattern probably occurs less than half the time. If you detect variations from the common descriptions, trace the arteries to their sources (aberrant hepatic arteries). Where are the cystic veins? To clarify the arrangement of structures of the hepatic pedicle, cut the peritoneum around the gallbladder and pull the gallbladder from its fossa on the right lobe of the liver.
Surface projection of abdominal organs Gallstones CT of liver and gall bladder Gallstones Cholangiogram showing biliary system Incise the falciform ligament and coronary ligaments to reflect the liver forward. Cut the inferior vena cava between the diaphragm and the liver. Examine the diaphragmatic surface of the liver, determining the extent and attachments of the coronary ligament. Find the bare area. On the visceral surface distinguish lobes and fissures and the attachment of the lesser omentum. Note that the lesser omentum is continuous with the coronary and falciform ligaments.
Complete the dissection of portal structures if not previously done. Note that branches of the portal vein, hepatic artery and bile duct always travel together. Follow the portal vein to the porta, identifying the right and left branches. On the left branch identify the transverse and umbilical parts, the round ligament of the liver (ligamentum teres hepatis - a remnant of the obliterated umbilical vein), and the ligamentum venosum. What are the fetal functions of the latter two structures? Identify the hepatic veins; how many are there? Read about the lymphatic drainage of the liver. Did you find any hepatic lymph nodes?
Review all of the tributaries of the portal vein and completely organize its drainage pattern. What organs does it drain? Consider the major sites of anastomoses between the portal system and the systemic (caval) veins, or portacaval anastomoses: esophageal veins, superior rectal veins, paraumbilical veins, posterior body wall (retroperitoneal) veins. These connections may be small and difficult to find if they have not been used to shunt blood from the portal to the caval veins. But they often become quite enlarged in cases of portal hypertension.
Venogram of the portal vein Read about the basic segmentation of the liver and the intrahepatic distribution of branches of the portal vein, hepatic ducts, and hepatic arteries. Is there any relationship between this intrahepatic pattern and the division of the liver into right and left lobes based on external appearance?