Stomach & Duodenum

1. Stomach & Duodenum Abdomen, Pelvis & Perineum Unit Lecture 5 د. حيدر جليل الأعسم

2. Abdominal Esophagus It is a muscular, collapsible tube about 25 cm long that joins pharynx to stomach. It enters the abdomen through an opening in diaphragm to the left of midline. After a short course 0.5 inch, it enters the stomach on its right side. Relations: Anteriorly:left liver lobe & left vagus. Posteriorly:left crus of diaph.& right vagus Arterial supply:from the left gastric artery. Venous drainage:left gastric vein, a tributary of the portal vein. Lymph Drainage:vessels follow arteries into left gastric nodes. Nerve Supply:anterior & posterior gastric nerves (vagi) & sympathetic branches of the thoracic part of the sympathetic trunk. Gastroesophageal Sphincter No anatomic sphincter, but (physiologic sphincter of lower esophagus)

3. Stomach It is J-shaped dilated portion of GIT that is situated in upper part of abdomen, extending from beneath left costal margin region into epigastric and umbilical regions. 2 openings: cardiac & pyloric orifices 2 curvatures: greater & lesser curvatures 2 surfaces: anterior & posterior surfaces 2 notches: cardiac notch & incisura angularis. Functions of the stomach: stores food, mixes food with gastric secretions to form chyme, and controls rate of delivery of chyme to small intestine. Divisions of Stomach: Fundus:is dome-shaped and projects upward and to left of cardiac orifice (full of gas) Body:extends from level of cardiac orifice to level of the incisura angularis. Pyloric antrum:extends from incisura angularis to the pylorus. Pylorus:is the most tubular part of the stomach. The thick muscular wall is called pyloric sphincter, and cavity of pylorus is the pyloric canal.

4. Stomach Lesser curvature Greater curvature Gastrosplenic omentum Pyloric orifice:is formed by pyloric canal (1 inch). It lies on transpyloric plane. Circular muscle coat of stomach is much thicker and forms anatomic and physiologic pyloric sphincter. Sphincter receives motor fibers from sympathetic system and inhibitory fibers from vagi. Mucous membrane of stomach is thick & vascular & is folded into numerous Rugae. Stomach muscular layers are longitudinal, circular & oblique

5. Relations of the stomach Anteriorly:anterior abdominal wall, left costal margin, left pleura and lung, diaphragm, and left lobe of liver Posteriorly:lesser sac, diaphragm, spleen, left suprarenal gland, upper part of left kidney, splenic artery, pancreas, transverse mesocolon, and transverse colon.

6. Arterial Supply of Stomach They are branches from celiac artery. Left gastric artery: It passes upward and to the left to reach esophagus and then descends along lesser curvature. It supplies lower third of esophagus and upper right part of stomach. Right gastric artery: arises from hepatic artery at upper border of pylorus and runs to left along lesser curvature. It supplies lower right part of stomach. Short gastric arteriesarise from splenic artery at hilum of spleen and pass forward in gastrosplenic omentum to supply the fundus. Left gastroepiploic arteryarises from splenic artery at hilum of spleen and passes forward in gastrosplenic omentum to supply stomach along upper part of greater curvature. Right gastroepiploic arteryarises from gastroduodenal artery. It passes to left and supplies stomach along lower part of greater curvature.

7. Venous drainage of stomach Veins drain into portal circulation. Left and Right gastric veinsdrain directly into portal vein. Short gastric veins& Left gastroepiploic veinsjoin splenic vein. Right gastroepiploic veinjoins the superior mesenteric vein

8. Nerve Supply Parasympathetic innervation: motor & secretomotor A. Anterior vagal trunk: formed from left vagus nerve. It supplies anterior surface of stomach. A large hepatic branch passes up to liver, and from this a pyloric branch passes down to pylorus. B. Posterior vagal trunk: formed from right vagus nerve. It divides into branches that supply mainly posterior surface of stomach. A large branch passes to celiac and superior mesenteric plexuses and is distributed to intestine as far as splenic flexure of colon and to pancreas. Sympathetic innervation: carries pain-transmitting nerve fibers & motor to Pyloric sphincter.

9. Small Intestine - Duodenum Small Intestine: extends from pylorus to ileocecal junction. It is divided into three parts: duodenum, jejunum, and ileum. Duodenum It is a C-shaped tube(25 cm long), which joins stomach to jejunum. It receives openings of bile and pancreatic ducts. It curves around the head of pancreas. First inch of duodenum is covered on its anterior and posterior surfaces with peritoneum and attached to lesser and greater omentum. Remainder of duodenum is retroperitoneal (partially covered by peritoneum). Mucous Membrane of duodenum: It is thick which is smoth in first part of duodenum and has numerous circular folds called plicae circulares in the remainder of the duodenum.

10. Parts of Duodenum It is divided into four parts. 1. First Part of the Duodenum It begins at pylorus and runs upward and backward on transpyloric plane at level of first lumbar vertebra L1. The relations of this part are as follows: Anteriorly:quadrate lobe of liver and gallbladder Posteriorly:lesser sac, gastroduodenal artery, bile duct and portal vein, and inferior vena cava Superiorly:entrance into lesser sac (Epiploic foramen) Inferiorly:head of the pancreas.

11. Parts of Duodenum 2. Second Part of the Duodenum It runs vertically downward in front of hilum of right kidney on right side of L2 & L3 vertebrae. About halfway down its medial border, bile duct and main pancreatic duct pierce duodenal wall. They unite to form ampulla that opens on summit ofarounded elevation major duodenal papilla. Accessory pancreatic duct, if present, opens into duodenum a little higher up on minor duodenal papilla. Anteriorly:fundus of gallbladder & right lobe of liver, transverse colon, and coils of small intestine Posteriorly:hilum of right kidney and right ureter Laterally: ascending colon, right colic flexure, and right lobe of liver Medially:head of pancreas, bile duct, and main pancreatic duct

12. Parts of Duodenum 3. Third Part of the Duodenum runs horizontally toward left on subcostal plane passing anterior to vertebral column & following lower margin of head of pancreas. Relations: Anteriorly:root of mesentery of small intestine, superior mesenteric vessels, and coils of jejunum Posteriorly:right ureter, right psoas muscle, inferior vena cava, and aorta Superiorly:head of pancreas Inferiorly:Coils of jejunum

13. Parts of Duodenum 4. Fourth Part of the Duodenum It runs upward and to left to duodenojejunal flexure. This flexure is surrounded by a fold of peritoneum containing muscle fibers called suspensory muscle (ligament) of duodenum (ligament of Treitz)which is attached to right crus of the diaphragm. Relations: Anteriorly:beginning of root of mesentery & coils of jejunum. Posteriorly:left margin of aorta and medial border of left psoas muscle.

14. Blood Supply of the Duodenum Arterial Supply: Upper half is supplied by superior pancreaticoduodenal artery, a branch of gastroduodenal artery. Lower half is supplied by inferior pancreaticoduodenal artery, a branch of superior mesenteric artery. Venous Drainage: Superior pancreaticoduodenal vein drains into portal vein; inferior vein joins superior mesenteric vein. Nerve Supply: sympathetic & parasympathetic (vagus) nerves from celiac superior mesenteric plexuses.

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