Stomach & Duodenum

Abdomen, Pelvis & Perineum Unit Lecture 5األعسم. جليل حيدر د

Abdominal EsophagusIt 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 vagusArterial 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 SphincterNo anatomic sphincter, but (physiologic sphincter of lower esophagus)

StomachIt 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 orifices2 curvatures: greater & lesser curvatures2 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.

StomachLesser curvatureGreater 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

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

Arterial Supply of StomachThey 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 arteries arise from splenic artery at hilum of spleen and pass forward in gastrosplenic omentum to supply the fundus.Left gastroepiploic artery arises from splenic artery at hilum of spleen and passes forward in gastrosplenic omentum to supply stomach along upper part of greater curvature.Right gastroepiploic artery arises from gastroduodenal artery. It passes to left and supplies stomach along lower part of greater curvature.

Venous drainage of stomachVeins drain into portal circulation. Left and Right gastric veins drain directly into portal vein. Short gastric veins & Left gastroepiploic veins join splenic

vein. Right gastroepiploic vein joins the superior mesenteric vein

Nerve SupplyParasympathetic 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.

Small Intestine - DuodenumSmall Intestine: extends from pylorus to ileocecal junction. It is divided into three parts: duodenum, jejunum, and ileum.

DuodenumIt is a C-shaped tube(25 cm long), whichjoins 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.

Parts of DuodenumIt is divided into four parts.1. First Part of the DuodenumIt 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 gallbladderPosteriorly: lesser sac, gastroduodenal artery, bile duct and portal vein, and inferior vena cavaSuperiorly: entrance into lesser sac (Epiploic foramen)Inferiorly: head of the pancreas.

Parts of Duodenum2. Second Part of the DuodenumIt 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 of a rounded 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 intestinePosteriorly: hilum of right kidney and right ureterLaterally: ascending colon, right colic flexure, and right lobe of liverMedially: head of pancreas, bile duct, and main pancreatic duct

Parts of Duodenum3. Third Part of the Duodenumruns 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 jejunumPosteriorly: right ureter, right psoas muscle, inferior vena cava, and aortaSuperiorly: head of pancreasInferiorly: Coils of jejunum

Parts of Duodenum4. Fourth Part of the DuodenumIt 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.

Blood Supply of the DuodenumArterial 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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