STOMACH AND DUODENUM 10-27

STOMACH and

DUODENUM

NORMAN V.VALERA,M.D.

STOMACH

The expanded part of the digestive system between the esophagus and the small intestine

Acts as a food blender and reservoir, its chief function is enzymatic digestion. The gastric juice gradually converts a mass of food into a semi-liquid mixture, CHYME, which passes fairly quickly into duodenum. Can hold 2-3 liters of food.

PARTS, AND ANATOMY OF STOMACH

CARDIA: the part surrounding the cardial orifice, the superior opening or inlet of the stomach.

FUNDUS: the dilated superior part that is related to the left dome of the diaphragm and is limited inferiorly by the horizontal plane of the cardial orifice. The cardial notch is between the esophagus and the fundus. The fundus usually lies posterior to the left 6th rib in the plane of MCL.

BODY: major part of the stomach between the fundus and the pyloric antrum.

PYLORIC PART: The funnel-shaped outflow part of the stomach; its wider part, the pyloric antrum, leads into the pyloric canal, its narrower part. The pylorus is the distal, sphincteric region of the pyrloric part. It is a marked thickening of the circular layer of smooth muscle that controls discharge of the stomach contents through the pyloric orifice into the duodenum.

STOMACH CURVATURES

LESSER CURVATURE: forms the shorter concave right border of the stomach. The angular incisure, the most inferior part of the curvature, indicates the junction of the body and the pyloric part of the stomach. The angular incisure lies just to the left of the midline.

GREATER CURVATURE: forms the longer convex left border of the stomach. It passes inferiorly to the left from the junction of the 5th interostal spce and MCL, then curves to the right,passing deep to the 9th or10th left cartilage as it continues medially to reach the pyloric antrum.

SURFACE ANATOMY OF THE STOMACH

INTERIOR OF THE STOMACH

ARTERIAL SUPPLY OF THE STOMACH

Arterial supply of the stomach arises from the celiac trunk and its branches.

Most blood is supplied by anastomoses formed along the lesser curvarture by the right and left gastric arteries, and along the greater curvature by the right and left gastro-omental ( gastro-epiploic) arteries. The fundus and the upper body receive blood from the short and posterior gastric arteries.

VEINS OF THE STOMACH

The veins of the stomach paralleled the arteries in position and course.

The right and left gastric veins drain into the hepatic portal vein; the short gstric veins and left gastro-omental veins drain into the splenic vein.

The right gastro-omental vein empties in the SMV.

A prepyloric vein ascends over the pylorus to the right gastric vein

GASTRIC LYMPHATIC VESSELS

Lymph from the superior two thirds of the stomach drains along the right and left gastric vessel to the gastric lymph node; lymph from the fundus and superior part of the body of the stomach also drains along the short gastric arteries and left gastro-omental vessels to the pancreaticosplenic lymph node

Lymph from the right two thirds of the inferior third of the stomach drains along the right gastro-omental vessels to the pyloric lymph nodes.

Lymph from the left one third of the greater curvature drains to the pancreaticoduodenal lymph nodes, which are located along th short gastric and splenic vessels

PARASYMPATHETIC NERVE SUPPLY OF THE STOMACH

Anterior vagal trunk, derived mainly from the left vagus nerve (CN X). It runs toward the lesser curvature of the stomach, where it gives off hepatic and duodenal branches. The rest of the anterior vagal trunk continues along the lesser curvature, giving rise to anterior gastric branches

Posterior vagal trunk, derived mainly from the right vagus. It supplies branches to the anterior and posterior surfaces of the stomach. It gives off a celiac branch, which passes to the celiac plexus, and then continues along the lesser curvature, giving rise to posterior gastric branches.

SYMPATHETIC NERVE SUPPLY OF THE STOMACH

From the T6- T9 segments of the spinal cord passes to the celiac plexus through the greater splanchnic nerve and is distributed through the plexuses around the gastric and gastro-omental arteries.

DUODENUM:DUODENUM:

First & shortestFirst & shortest part part of the small intestineof the small intestine

Widest and fixedWidest and fixed part part C – shaped, C – shaped, aboutabout 10 10

inches long ( 25 cm )inches long ( 25 cm ) BeginsBegins at the at the pyloruspylorus

on the on the R sideR side and and endsends at the at the duodenojejunal duodenojejunal junctionjunction on the on the left left sideside ( ( L2 vertebraL2 vertebra))

DIVISIONS:DIVISIONS: Superior ( 1Superior ( 1stst ) part ) part – –

5cm & lies anterolat. to the 5cm & lies anterolat. to the body of body of L1L1

Descending ( 2Descending ( 2ndnd ) ) – 7 to – 7 to 10cm & descends along the 10cm & descends along the R sides of R sides of L1 throughL1 through L3L3

Horizontal ( 3Horizontal ( 3rdrd ) ) – 6 to – 6 to 8cm & crosses 8cm & crosses L3L3

Ascending ( 4Ascending ( 4thth ) ) – 5cm & – 5cm & begins at the L of begins at the L of L3L3 and and

rises superiorly as far as rises superiorly as far as superior border of superior border of L2L2

SUPERIOR PART OF THE DUODENUM

Ascends from the pylorus and is overlapped by the liver and gallbladder

Peritoneum covers its anterior aspecct, bare of peritoneum posteriorly

Proximal part has the hepatoduodenal ligament attached superiorly, and the greater omentum attached to inferiorly

DESCENDING PART OF THE DUODENUM

Runs inferiorly, curving around the head of the pancreas.

Bile and main pancreatic ducts enter its posteromedial wall. This duct s usually unite to form the hepatopancreatic ampulla, which opens on an eminence, called major duodenal papilla

Entirely retroperitoneal

INFERIOR PART OF THE DUODENUM

Runs transversely to the left, passing over the IVC, aorta and L3 vertebra

Crosses superior mesenteric artery and vein and the root of the mesentery of the jejunum and ileum.

ASCENDING PART OF THE DUODENUM

Runs superiorrly and along the left side of the aorta to reach the inferior border of the body of the pancreas.

Supported by the attachment of the suspensory muscle of the duodenum( ligament of Treitz )

BLOOD SUPPLY:BLOOD SUPPLY:

Upper part – Upper part – superiorsuperior pancreaticoduodpancreaticoduodenalenal from from gastroduodenalgastroduodenal

Lower part –Lower part – inferiorinferior pancreaticoduodpancreaticoduodenalenal from superior from superior mesentericmesenteric

VENOUS DRAINAGEVENOUS DRAINAGE Superior Superior

pancreaticoduodpancreaticoduodenalenal vein drains vein drains into portal veininto portal vein

Inferior Inferior pancreaticoduodpancreaticoduodenalenal joins the joins the superior superior mesenteric veinmesenteric vein

VENOUS VENOUS DRAINAGE:DRAINAGE:

Superior Superior mesentericmesenteric veinvein w/c lies anterior w/c lies anterior and to the right of and to the right of the SMA in the root the SMA in the root of mesentery; ends of mesentery; ends posterior to the posterior to the neck of pancreas neck of pancreas where it where it unitesunites w/ w/ splenic veinsplenic vein to to form the form the portal portal vein.vein.

LYMPHATICS

ANTERIOR LYMPHATIC VESSELS- drain into pancreaticoduodenal lymph nodes, located along the superior and inferior pancreatoduodenal arteries, and into the pyloric lymph node( fig. 2.46)

POSTERIOR LYMPHATIC VESSEL- pass posterior to the head of the pancreas and drain into the superior mesenteric lymph nodes.

EFFERENT LYMPHATIC VESSELS from the duodenal lymph nodes drain into the celiac lymph nodes

NERVE SUPPLY

Derive from the VAGUS and GREATER and LESSER(ABDOMINOPELVIC) SPLANCHNIC NERVES by way of the celiac and superiormesenteric plexuses.

They are next conveyed to the duodenum via periarterial plexuses extending to the pancreaticoduodenal arteries.

HAVE A NICE DAY !