Upper GI Tract PDF

Upper GI Tract Supplemental Reading: Textbook, pages: 454 – 474 & 482 - 487  Notice and Agreement MGA – Lecture19 Upper GI Tract This session is being recorded Class recordings are distributed for the exclusive use of students in the LMU DeBusk College...

Upper GI Tract Supplemental Reading: Textbook, pages: 454 – 474 & 482 - 487  Notice and Agreement MGA – Lecture19 Upper GI Tract This session is being recorded Class recordings are distributed for the exclusive use of students in the LMU DeBusk College of Osteopathic Medicine. Student access to and use of class recordings are conditioned on agreement with the terms and conditions set below. Any student who does not agree to them is prohibited from accessing or making any use of such recordings. Any student accessing class recordings (1) acknowledges the faculty members’ intellectual property rights in recorded lectures and class materials and that distribution of the recordings violates the DCOM Copyright Policy; (2) recognizes the privacy rights of fellow students who speak in class; (3) accepts that distributing, posting, or uploading class recordings to students or any other third party not authorized to receive them or to those outside DCOM is an Honor Code violation; and (4) agrees that recordings are to be accessed and used only as directed by the faculty member(s) teaching the course.  Learning Objectives Describe basic anatomy and landmarks involving portions making up the upper GI tract (esophagus, stomach, duodenum, jejunum, ileum) Distinguish the parts of the stomach and describe its spatial relationships to surrounding organs and mesenteries Identify and describe portions of the upper GI tract that are susceptible to common (high-yield) pathologic conditions (I.e. third part of duodenum and relationship to SMA) Describe the pattern of sympathetic and parasympathetic innervation of the upper GI tract. Identify blood supply to all viscera covered & know locations of anastomoses * * Esophagus Inner circular smooth muscle; outer longitudinal muscle (upper 1/3 – skeletal; distal 1/3 – smooth muscle) Passes thru 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 Z-line vertebra Z-line → zagged line where the mucosa abruptly changes from a stratified squamous to simple columnar epithelium Superior to this line, the diaphragmatic musculature surrounding the esophagus functions as the inferior esophageal sphincter  Blood supply to the abdominal portion of the esophagus is via branches of the left gastric artery (branch of the celiac trunk) and inferior phrenic arteries (branches of abdominal aorta) Innervation is provided by the esophageal plexus (anterior and posterior vagal trunks (parasymp.) & greater splanchnic nerves (symp.))  Para-esophageal hernia Less common Cardia remains in place; often contains the fundic portion of stomach Sliding esophageal hernia More common Abdominal portion of esophagus, cardia & maybe fundic portion of stomach (text pages 483 & 484)  Clinical Considerations GERD – Gastroesophageal Reflux Disease → causes: decreased tone of lower esophageal sphincter, sliding hiatal hernia, common in adults -Can lead to Barrett’s esophagus Peptic Ulcers - causes: mucosa exposed to gastric acid, H. pylori infection, acute lesions are small & 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 4:1  Stomach Large J-shaped organ between the esophagus & small intestine Located in the left hypochondrium, epigastric and umbilical regions Size & shape are quiet variable (can hold between 2-3 liters of fluid) Primary function → food blender (enzymatic digestion) & reservoir  Greater Curvature → longer, convex left border of the stomach associated with the greater omentum and right/left gastro- omental blood vessels Lesser Curvature → shorter, concave right border of the stomach associated with the lesser omentum and right/left gastric blood vessels  Lesser Omentum Portions of the Bile Duct, Hepatic Artery & Portal Vein st ric are contained a t oga Hep ment within the Lig a Hepatoduodenal Ligament Hepatoduodenal Ligament  Cardia – esophagogastric junction Fundus – located above & to the left of cardia (may contain air) Cardiac notch junction between cardia & fundus Body – major portion of stomach Angular Incisor/Notch – junction of body & pylorus Pyloric region – funnel-shaped outflow region Pyloric antrum – begins at the angular notch Pyloric canal – narrower portion Pylorus – distal sphincteric region  Cardiac Notch Angular Incisor/ Notch Stomach Musculature - 3 layers Gilroy Fig 13.3B, p. 156 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 to the Stomach → branches of the Celiac Artery Venous Drainage → similarly named veins → Portal Venous System Lymphatic drainage → Gastric, Pyloric Lymph Nodes Parasympathetic Innervation → Anterior & Posterior Vagal Trunks Sympathetic Innervation → Greater Splanchnic Nerves  Celiac Trunk Branches: 1. Left Gastric 2. Splenic 3. Common Hepatic 1 3 2 Superior Mesenteric Artery & Vein (crosses over 3rd part of duodenum) Common Hepatic Artery Branches: 1. Gastroduodenal A. 2. Proper Hepatic A. 2 1 On either side of the Celiac Trunk are 2 large Celiac Ganglia: Receive Fibers from Greater Splanchnic Nerve Network of fibers called the Celiac Plexus Branches of the Celiac Artery On either side of the Celiac Trunk Parasympathetic Innervation → are 2 large Celiac Ganglia: Anterior & Posterior Vagal Receive Fibers from Greater Trunks Splanchnic Nerves Network of fibers called the Sympathetic Innervation → Celiac Plexus Greater Splanchnic Nerves Small Intestine Extends from pylorus to ileocecal junction Primary function is absorption of nutrients Approximately 6 – 7 meters in length Duodenum Jejunum Ileum  Duodenum Forms C-shaped loop around the head of the pancreas Mostly retroperitoneal Superior or First part → Continuous with the pylorus; completely peritonealized; lacks circular folds; anterior to the bile duct, gastroduodenal artery & portal vein Second or Descending Part → secondarily retroperitoneal; circular folds are present; common bile duct & main pancreatic duct open onto the duodenal papilla  Duodenum (cont.) Inferior or Third part → secondarily retroperitoneal; circular folds are present; located posterior to the superior mesenteric blood vessels; crosses the body of the L3 vertebra 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)  1 4 2 3 1st part - duodenal bulb (ampulla), prone to ulcers 2nd part - duodenal papilla; foregut vs. midgut 3rd part - crossed by Superior Mesenteric blood vessels Circular folds = plicae circulares 3rd part of the duodenum → ‘nut- cracker’ position between the origin of the SMA & aorta; neck of the pancreas anterior to the aorta between origins of celiac trunk & SMA Duodenal Papilla 2/3 of the Transverse Colon  Blood Supply to the Duodenum → branches of the Celiac & Superior Mesenteric Arteries Venous Drainage → similarly named veins → Portal Venous System Lymphatic drainage → Pyloric Lymph Nodes & Superior Mesenteric Lymph Nodes Parasympathetic Innervation → Vagus Nerves Sympathetic Innervation → Greater & Lesser Splanchnic Nerves  The duodenum receives blood from BOTH the Celiac Trunk and Superior Mesenteric Artery (SMA): 1 1. Anterior & Posterior Superior Pancreatico- dudodenal Arteries from the Superior Pancreaticoduodenal Branch of the 2 Gastroduodenal Artery 2. Anterior & Posterior Inferior Pancreatico- duodenal Branches from the Inferior Pancreaticoduodenal Branch of the SMA  Jejunum & Ileum Length averages 22 feet, of which the upper 2/5ths is jejunum & the lower 3/5ths is ileum Jejunum begins at the duodenojejunal flexure on the left side of the L2 vertebra Ileum Ends at the ileoceccal junction Meckel’s Diverticulum – remnant of the proximal part of the yolk sac; follows the rule of twos → 2 inches long, 2 feet from the ileoceccal junction & occurs in 2% of the population Mesentery Proper → supports the jejunum & ileum Base 6-9 inches; fans out to support 22 feet of small intestine Base of the mesentery extends from the left side of the L2 vertebra to the right sacroiliac joint  Jejunum Ileum  Distinguishing Characteristics of the Jejunum and Ileum Characteristic Jejunum Ileum Color Deeper Red Paler Pink Caliber 2 – 4 cm 2 – 3 cm Wall Thick & heavy Thin & light Vascularity Greater Less Vasa Recta Long Short Arcades A few large loops Many short loops Fat in Mesentery Less More Circular Folds Large, tall & closely packed Low & sparse Lymphoid Nodules Few Many (Peyer’s patches)  Blood Supply to the jejunum & ileum → Jejunal & Ileal branches of the Superior Mesenteric Artery Venous Drainage → similarly named veins → Portal Venous System Lymphatic drainage → Superior Mesenteric & Ileocolic Lymph Nodes Parasympathetic Innervation → Vagus Nerves Sympathetic Innervation → Greater & Lesser Splanchnic Nerves Branches of the Superior Mesenteric Artery  Generalization Innervation - Foregut & Midgut Sympathetic: Thoracic Splanchnic Nerves Duodenal Parasympathetic: Vagus Papilla 2/3 of the Transverse Colon Innervation - Hindgut Sympathetic: Lumbar Splanchnic Nerves Parasympathetic: Pelvic Splanchnic Nerves  Blood supply review → Foregut Abdominal aorta Celiac trunk Superior Inferior mesenteric a. mesenteric a. Left Splenic a. Common Gastric a. hepatic a. Esophageal Left gastro- Short gastric Proper Gastroduodenal a. branches omental a. a. hepatic a. Right gastric a. (?) Superior pancreatico- Right gastro- omental a. Cystic a. Right & Left duodenal a. Hepatic aa.  Blood supply review → Midgut Abdominal aorta Celiac trunk Superior Inferior mesenteric a. mesenteric a. Inferior Jejunal & Ilieal Middle pancreatico- Ileocolic a. colic a. aa. duodenal a. Right colic a. Anastomotic loops & arcades Vasa recta  Clinical Considerations (cont.) Ostomies – surgical ‘externalization’ of a portion of the GI tract to the anterior abdominal wall (‘by-pass’ procedure) Gastrostomy Jejunostomy Ileostomy Colostomy Thanks for your time!