DISSECTION 26 The Stomach, Celiac Trunk, and SpleenReferences: M1 230-238, 263-265; N267-269, 289-293; N275-277, 299-303; R 284-285, 299-300, 302- 303, 304-307AT THE END OF THIS LABORATORY PERIOD YOU WILL BE RESPONSIBLE FOR THEIDENTIFICATION AND DEMONSTRATION OF THE STRUCTURES LISTED BELOW:1. Viscera, visceral parts, and visceral features: - stomach (cardioesophageal junction, esophageal orifice, cardiac portion, lesser curvature, angular notch, greater curvature, body, fundus, pyloric portion, pyloric antrum, pyloric canal, pylorus), spleen, first part of duodenum, caudate lobe of liver, pancreas.2. Ligaments and mesenteries: lesser omentum (hepatogastric ligament, hepatoduodenal ligament), gastrolienal ligament.3. Arteries: celiac trunk (artery), left gastric, left hepatic branch of left gastric, splenic, left gastro- omental, short gastric, hepatic, right gastric, right gastro-omental, gastroduodenal, superior pancreatico-duodenal.4. Veins: left gastric, short gastric, left gastro-omental, superior mesenteric, splenic, portal, inferior vena cava.5. Nerves: anterior vagal trunk, posterior vagal trunk.6. Subdivisions of peritoneal cavity: omental (epiploic) foramen, omental bursa.YOU SHOULD ALSO BE ABLE TO DO THE FOLLOWING THINGS:1. Demonstrate understanding of the blood supply and lymphatic drainage of the stomach and associated viscera.2. Trace the path of blood flow from the stomach to the heart by the normal route and when there is portal hypertension. Show that you understand why hemorrhage may occur at the gastroesophageal junction when the portal vein is obstructed in the liver.3. List and discuss four important sites of anastomosis between the portal system and the systemic veins.4. Name the adult derivatives of the mesenteries of the stomach.5. Describe the innervation of the stomach. Stomach is the CARDIAC PORTION of the stomach surrounding the ESOPHAGEAL ORIFICE (G2.24; Observe the size, shape, and position of the N267-269; N275-277). The right border of theSTOMACH in your specimen. Compare it with stomach is called the LESSER CURVATURE, andstomachs in other specimens. Review the the angle or notch which is usually found in thisperitoneal attachments of the stomach. The border is called the ANGULAR NOTCH (orstomach is divided into different anatomicalareas. Near the CARDIOESOPHAGEAL JUNCTION
Dissection 26, Stomach, Celiac Trunk, Spleen Page 2incisure). The mesentery connecting the lesser explored (G2.25, 28, 34; N270, 290-293; N278,curvature to the liver is the HEPATOGASTRIC 300-303).LIGAMENT of the LESSER OMENTUM. On the leftborder, or GREATER CURVATURE identify the Celiac Trunkangle between the esophagus and the fundus ofthe stomach. The FUNDUS of the stomach is that The posterior wall of the omental bursa ispart of the stomach superior to a transverse plane formed largely by the PANCREAS. Near the upperthrough the cardiac notch. The BODY of the border of the pancreas look for a bulge in thestomach lies between the fundus and the angular peritoneum produced by the CELIAC ARTERYnotch, and the PYLORIC PORTION is that part (also called celiac trunk or celiac axis). If thedistal to the angular notch. The pyloric portion is celiac artery is not immediately apparent, lift thesubdivided into PYLORIC ANTRUM and PYLORIC left portion of the stomach ventrally and look forCANAL. The end of the canal is the PYLORUS, a peritoneal fold extending from the cranialpresenting an ostium through which the stomach portion of the lesser curvature across the posterioris continuous with the duodenum. wall of the omental bursa to the upper border of the pancreas. This fold is produced by the LEFT Examine the OMENTAL (EPIPLOIC) GASTRIC ARTERY, one of the three branches ofFORAMEN and identify the structures which form the celiac trunk. Carefully clean the left gastricits boundaries (G2.20; N267; N275). The artery on the lesser curvature and trace it back toHEPATODUODENAL LIGAMENT and the two the celiac trunk. Try not to destroy thestructures it connects form three of these accompanying LEFT GASTRIC VEIN and watchboundaries: inferiorly, the FIRST PART OF THE particularly for its esophageal tributaries. As youDUODENUM; anteriorly, the HEPATODUODENAL clean the left gastric artery, look for a branchLIGAMENT; superiorly, the CAUDATE LOBE OF passing through the lesser omentum into the leftTHE LIVER. The posterior boundary is formed by lobe of the liver. This ABERRANT LEFT HEPATICthe INFERIOR VENA CAVA just below its entrance BRANCH of the left gastric artery is important tointo the liver (G2.23; N266; N274). the surgeon removing all or part of the stomach (G2.55C; N297; N305). If this artery is Lift the cut edge of the greater omentum and accidentally damaged, part of the liver will haveplace your hand behind the stomach to lost its blood supply.demonstrate the continuity of this space with theepiploic foramen. This portion of the peritoneal When the celiac artery has been identified,cavity is called the OMENTAL BURSA, or lesser find the SPLENIC ARTERY and trace it along thesac, and it is a blind pouch which normally upper border of the pancreas to the hilum of thecommunicates with the rest of the peritoneal spleen. Branches of the splenic artery whichcavity only through the epiploic foramen. should now be identified are the LEFT GASTRO- OMENTAL ARTERY, which can be found in the Identify the GASTROLIENAL (or greater omentum a short distance from the greatergastrosplenic) LIGAMENT which connects the curvature, and the SHORT GASTRIC ARTERIES,stomach and the spleen (G2.21A, 29; N264, 289; which pass to the fundus of the stomach (G2.25,N272, 299). 28, 34; N270, 290-292; N278, 300-301). With scissors, bisect stomach vertically The last branch of the celiac trunk is thethrough the angular notch which is the line of HEPATIC ARTERY. Find the hepatic artery byjunction between the body of the stomach and the pulling the hepatoduodenal ligament to the right.pyloric antrum. Extend this cut into the lesser As you do so, look for a fold in the peritoneumomentum. After cleaning out the contents of the between the celiac artery and the hepatoduodenalstomach (into the tissue container, NOT into the ligament. This fold lies over the hepatic artery,sinks), the two portions may be retracted to either which should be cleaned to its entrance into theside and the interior of the omental bursa may be hepatoduodenal ligament.
Dissection 26, Stomach, Celiac Trunk, Spleen Page 3 There are two branches from the hepatic TRUNK as it passes through the esophageal hiatusartery which should be identified: the RIGHT (G2.63; N308-310; N318-320).GASTRIC ARTERY and the GASTRODUODENALARTERY which branches into the SUPERIOR Examine the SPLEEN and its mesentericPANCREATICO-DUODENAL ARTERY and the attachments again. Study the size, shape, andRIGHT GASTRO-OMENTAL ARTERY. The RIGHT impressions of the spleen. Examine itsGASTRIC ARTERY is found on the right portion of mesenteries near the hilum. In the hilum, identifythe stomach on the lesser curvature, and the right the arteries and the veins. A number of veinsgastro-omental artery on the greater curvature unite close to or at some distance from the hilum(G2.25, 28, 34; N270, 290-292; N278, 300-301). to form the SPLENIC VEIN (G2.60; N299-303; N309-313). There are two extra-splenic veins, Spleen the SHORT GASTRIC and LEFT GASTRO- OMENTAL VEINS, draining into the splenic vein Before examining the SPLEEN, return to the before it joins with the SUPERIOR MESENTERICregion of the cardioesophageal junction and VEIN to form the PORTAL VEIN. Study theidentify the ANTERIOR VAGAL TRUNK, which is formations of the portal vein in your cadaver.derived principally from the left vagus nerve.This nerve can be best located by pulling upon the Consult your text for the lymphatic drainageanterior vagal trunk just above the diaphragm. of the stomach and spleen. Look for some of theSimilarly, pull upon the posterior vagal trunk in lymph nodes in the area.the thorax and identify the POSTERIOR VAGAL______________________________________________________________________________________________ STUDY QUESTIONS1. Label the features and subdivisions 1. a. pylorus of the stomach shown on the diagram. b. angular notch c. cardiac portion of stomach d. cardiac notch e. fundus f. body of stomach g. antrum2. What are the adult derivatives 2. The ventral mesentery becomes the hepatogastric of the mesenteries of the stomach? ligament; the dorsal mesentery becomes the greater omentum, the gastrosplenic ligament, the gastrophrenic ligament, the phrenicolienal ligament, and the lienorenal ligament.
Dissection 26, Stomach, Celiac Trunk, Spleen Page 43. What structures form the anterior 3. The lesser omentum, the dorsal wall of the stomach, wall of the omental bursa? and the gastrocolic ligament.4. Trace the route of blood flow from 4. a) short gastric vein – splenic vein -- portal vein -- the fundus of the stomach to the heart, branches of portal vein -- liver sinusoids -- naming all vessels traversed tributaries to hepatic veins --hepatic veins -- a) by the normal route, and inferior vena cava-- right atrium. b) when there is intra hepatic obstruction of the portal vein. b) short gastric vein – splenic vein -- portal vein -- left gastric vein -- esophageal tributary to left5. What is the significance of the gastric vein – esophageal tributary to azygos vein – route given in answer 4.b)? azygos vein -- superior vena cava – right atrium.6. Identify the vessels indicated: There are many other alternate routes that could be taken in answering either a) or b). 5. When the venous pressure in the portal system is elevated and there is partial obstruction to the portal flow through the liver, blood is shunted around the liver through the esophageal veins to the superior vena cava. The esophageal venous plexus just deep to the mucous membrane dilates and produces varicosities (esophageal varices) which protrude into the lumen of the esophagus. These varicosities are subject to trauma and are easily damaged, with severe hemorrhage and death frequently resulting. 6. a. superior pancreaticoduodenal artery b. hepatic artery c. cystic artery d. right hepatic artery e. left hepatic artery f. right gastric artery g. celiac trunk h. left gastric artery i. short gastric artery j. splenic artery k. left gastroepiploic artery l. right gastroepiploic artery
Dissection 26, Stomach, Celiac Trunk, Spleen Page 57. Locate the cell bodies of nerve 7. Inferior ganglion of the vagus and the dorsal motor fibers in the anterior vagal trunk. nucleus of the vagus.8. In general, how does lymph get 8. In general, lymph drains first into nodes associated from the gastrointestinal tract back into the blood stream? with the arteries which supply the organ under consideration. Then it drains into the intestinal lymph trunk – left lumbar trunk -- cisterna chyli -- thoracic duct -- left subclavian vein.9. Locate the cell bodies of pain fibers 9. Dorsal root ganglia T6 to T9. Dorsal root, nerve to the region of the pylorus. Through trunk, anterior primary ramus, white ramus, what nerves and nerve-like structures sympathetic ganglion (no synapse, of course), do these fibers pass to reach the pylorus? greater splanchnic nerve, celiac ganglion (again, no synapse), celiac plexus, plexus on hepatic artery, plexus on right gastric artery, pylorus.10. What structures are found in 10. The tail of the pancreas and the splenic vessels. lienorenal ligament?11. Is the spleen normally palpable? 11. No12. In what mesentery does the 12. The dorsal mesentery of the stomach. spleen develop?13. Name three organs supplied with 13. The spleen, pancreas, and stomach. blood by the splenic artery.14. Into which nodes does lymph from 14. See M1234-238 and H632-633. the following parts of the stomach drain? a) cardiac region and most of lesser curvature. b) right half of greater curvature. c) left half of greater curvature.15. Name four places where the esophagus is normally constricted when it is full.16. What arteries anastomose on the greater curvature of the stomach? On the lesser curvature?17. A fracture of the left l0th rib posterior to the midaxillary line would be likely to damage what organ? LJ:bh revised 06/18/09