Upper GI Tract- Esophagus, Stomach, Small Intestine.pdf

Upper GI Tract Esophagus Inner circular smooth muscle; outer longitudinal muscle (upper 1/3 skeletal; distal 1/3 smooth muscle) Passes through the esophageal hiatus of the diaphragm at approximately T10 vertebral...

Upper GI Tract Esophagus Inner circular smooth muscle; outer longitudinal muscle (upper 1/3 skeletal; distal 1/3 smooth muscle) Passes through the esophageal hiatus of the diaphragm at approximately T10 vertebral level Terminates by entering the stomach at the level of the cardiac orifice Esophagogastric junction lies to the left of the T11 vertebra Z-line: a zigzagged line where the mucosa abruptly changes from a stratified squamous to simple columnar epithelium Blood supply: branches of the left gastric artery (branch of the celiac trunk) and inferior phrenic arteries (branches of abdominal aorta) Innervation: esophageal plexus (anterior and posterior vagal trunks, parasympathetic; greater splanchnic nerves, sympathetic) Types of Hiatal Hernias Type Description Para-esophageal Less common; cardia remains in place; often contains the fundic https://www.turbolearn.ai/content/63c28849-73ab-4970-94f3-88d314789412 9/29/24, 10 48 PM Page 1 of 6 :  hernia portion of stomach Sliding More common; abdominal portion of esophagus, cardia, and maybe esophageal fundic portion of stomach hernia Clinical Considerations GERD (Gastroesophageal Reflux Disease): causes include decreased tone of lower esophageal sphincter, sliding hiatal hernia; common in adults; can lead to Barrett's esophagus Peptic Ulcers: causes include mucosa exposed to gastric acid, H. pylori infection; acute lesions are small and shallow, whereas chronic ulcers may erode into the muscularis externa or perforate the serosa; 98% of ulcers are in the first part of duodenum or stomach, in a ratio of 4:1 Stomach Large J-shaped organ between the esophagus and small intestine Located in the left hypochondrium, epigastric, and umbilical regions Primary function: food blender (enzymatic digestion) and reservoir Size and shape: quite variable; can hold between 2-3 liters of fluid https://www.turbolearn.ai/content/63c28849-73ab-4970-94f3-88d314789412 9/29/24, 10 48 PM Page 2 of 6 :  Stomach Regions Region Description Cardia esophagogastric junction Fundus located above and to the left of cardia; may contain air Body major portion of stomach Angular incisor/notch junction of body and pylorus Pyloric region funnel-shaped outflow region Pyloric antrum begins at the angular notch Pyloric canal narrower portion Pylorus distal sphincteric region Stomach Musculature 3 layers: inner oblique, middle circular, and outer longitudinal Interior of the stomach: Gastric folds (rugae): longitudinal folds of gastric mucosa; diminish as the stomach is distended Gastric canal: groove which forms between rugae and lesser curvature Blood Supply and Innervation Blood supply: branches of the celiac artery https://www.turbolearn.ai/content/63c28849-73ab-4970-94f3-88d314789412 9/29/24, 10 48 PM Page 3 of 6 :  Venous drainage: similarly named veins; portal venous system Lymphatic drainage: gastric and pyloric lymph nodes Parasympathetic innervation: anterior and posterior vagal trunks Sympathetic innervation: greater splanchnic nerves Small Intestine Extends from pylorus to ileocecal junction Primary function: absorption of nutrients Approximately 6-7 meters in length Duodenum Forms C-shaped loop around the head of the pancreas Mostly retroperitoneal Four parts: 1. Superior or First part: continuous with the pylorus; completely peritonealized; lacks circular folds; anterior to the bile duct, gastroduodenal artery, and portal vein 2. Second or Descending Part: secondarily retroperitoneal; circular folds are present; common bile duct and main pancreatic duct open onto the duodenal papilla 3. Inferior or Third part: secondarily retroperitoneal; circular https://www.turbolearn.ai/content/63c28849-73ab-4970-94f3-88d314789412 9/29/24, 10 48 PM Page 4 of 6 :  folds are present; located posterior to the superior mesenteric blood vessels; crosses the body of the L3 vertebra 4. Fourth or Ascending Part: secondarily retroperitoneal; circular folds are present; ends at the duodenojejunal flexure; supported by the suspensory ligament of the duodenum (Lig. of Treitz) Jejunum and Ileum Length: averages 22 feet, of which the upper 2/5ths is jejunum and the lower 3/5ths is ileum Jejunum begins at the duodenojejunal flexure on the left side of the L2 vertebra Ileum ends at the ileocecal junction Characteristics of Jejunum and Ileum Characteristic Jejunum Ileum Color Deeper red Paler pink Caliber 2-4 cm 2-3 cm Wall Thick and heavy Thin and light Vascularity Greater Less Vasa recta Long Short Arcades A few large loops Many short loops https://www.turbolearn.ai/content/63c28849-73ab-4970-94f3-88d314789412 9/29/24, 10 48 PM Page 5 of 6 :  Fat in mesentery Less More Circular folds Large, tall, and closely packed Low and sparse Lymphoid nodules Few Many (Peyer's patches) Blood Supply and Innervation Blood supply: jejunal and ileal branches of the superior mesenteric artery Venous drainage: similarly named veins; portal venous system Lymphatic drainage: superior mesenteric and ileocolic lymph nodes Parasympathetic innervation: vagus nerves Sympathetic innervation: greater and lesser splanchnic nerves https://www.turbolearn.ai/content/63c28849-73ab-4970-94f3-88d314789412 9/29/24, 10 48 PM Page 6 of 6 :