Anatomy of GIT I PDF

Faculty of Medicine Medical Education- Damietta University Level 1 Semester 3 Module 1A  Anatomy of gastrointestinal canal I Dr. Gamal Elsayed  Instructor information Contact: Anatomy Department. Official email: [email protected] Mobile (op...

Faculty of Medicine Medical Education- Damietta University Level 1 Semester 3 Module 1A  Anatomy of gastrointestinal canal I Dr. Gamal Elsayed  Instructor information Contact: Anatomy Department. Official email: [email protected] Mobile (optional): 01014935906 Academic hours: ……………day: 00:00-00:00 AM …………...day: 00:00-00:00 AM Lecture topics Anatomy of esophagus Anatomy of stomach Duodenum Jejunum and ileum Learning Outcomes By the end of the lecture, the students will be able to: - Know the anatomy of esophagus - Know the anatomy of the stomach - Know the anatomy of small intestine and its parts Case scenario, Clinical Correlate, Practice points A 15-year-old boy complaining of pain in the lower right part of the anterior abdominal wall was seen by a physician. He had a furred tongue and was extremely tender in the lower right quadrant. The abdominal muscles in that area were found to be firm (rigid) on palpation and became more spastic when increased pressure was applied (guarding). A diagnosis of acute appendicitis was made.  Esophagus (Abdominal Portion) It is a muscular, collapsible tube about 10 in.(25 cm) long that joins the pharynx to the stomach. Its greater part lies within the thorax. It enters the abdomen through the right crus of the diaphragm. After a course of about 0.5 in. (1.25 cm), it enters the stomach on its right side. Blood Supply Arteries The arteries are branches from the left gastric artery. Veins The veins drain into the left gastric vein (a tributary of the portal vein). Nerve Supply a. The nerve supply is the anterior and posterior gastric nerves (vagi) and b. Sympathetic branches of the thoracic part of Lymph Drainage The lymph vessels follow the arteries into the left gastric nodes.  Stomach It is the dilated portion of the alimentary canal. It is situated in the upper part of the abdomen: a. Extending from the left costal margin. b. The epigastric region. c. Umbilical regions. It lies under cover of the lower ribs. It is J-shaped Two openings (cardiac and pyloric) Two curvatures (greater and lesser)  It is fixed at both ends but is mobile in between. in the short, obese person (steer- horn stomach) and in the tall, thin person (J-shaped stomach). Its shape undergoes variation in the same person and depends on: a. The volume of its contents. b. The position of the body. c. The phase of respiration. The stomach is divided into: Fundus: a. This is dome-shaped and projects upward and to the left of the cardiac orifice. b. It is usually full of gas. Body: a. This extends from the cardiac orifice to incisura angularis (in the lower part the lesser curvature). Pyloric antrum: a. This extends from the incisura angularis to the pylorus. Pylorus: a. This is the tubular part of the stomach. b. The thick muscular wall (pyloric sphincter). c. The cavity of the pylorus is the pyloric canal.  Lesser curvature a. Forms the right border of the stomach and b. Extends from the cardiac orifice to the pylorus. c. It is suspended from the liver by the lesser omentum. Greater curvature a. Extends from the left of the cardiac orifice, along the left border of the stomach to the pylorus. b. The gastrosplenic omentum (ligament) extends from the upper part of the greater curvature to the spleen, c. The greater omentum extends from the lower part of the greater curvature to the transverse colon.  Cardiac orifice: a. is where the esophagus enters the stomach. b. Although no anatomic sphincter can be demonstrated here Pyloric orifice: a. Formed by the pyloric canal. b. The circular muscle coat forms the anatomic and physiologic pyloric sphincter. c. The pylorus lies on the transpyloric plane.  Mucous membrane of the stomach: a. Forms rugae b. That are longitudinal in direction. c. The folds flatten out when the stomach is distended. Muscular wall of the stomach: contains longitudinal fibers, circular fibers, and oblique fibers. Peritoneum: a. Completely surrounds the stomach. b. It leaves the lesser curvature as the lesser omentum and c. It leaves the greater curvature as the gastrosplenic omentum and the greater omentum. Blood Supply of the stomach Arteries The arteries are branches of celiac artery. 1- The left gastric artery: a. It descends along the lesser curvature of the stomach. b. It supplies the lower third of the esophagus and the upper right part of the stomach. 2- The right gastric artery a. It arises from the hepatic artery at the upper border of the pylorus b. It runs to the left along the lesser curvature. c. It supplies the lower right part of the stomach. 3- The short gastric arteries a. It arise from the splenic artery b. Pass in the gastrosplenic omentum (ligament) to supply the fundus. 4- The left gastroepiploic artery a. It arises from the splenic artery b. Passes in the gastrosplenic omentum (ligament) to c. Supply the stomach along the upper part of the greater curvature. 5- The right gastroepiploic artery a. It arises from the gastroduodenal branch of the hepatic artery. b. It supplies the stomach along the lower part of the greater curvature. Veins a. They drain into the portal circulation. b. The left and right gastric veins drain into the portal vein. c. The short gastric veins and the left gastroepiploic veins join the splenic vein. d. The right gastroepiploic vein joins the superior mesenteric vein.  Lymph Drainage: a. The lymph vessels follow the arteries into the left and right gastric nodes. b. The left and right gastroepiploic nodes. c. The short gastric nodes. All lymph from the stomach passes to the celiac nodes. The nerve supply: a. Sympathetic fibers from the celiac Nerve Supply plexus b. Parasympathetic fibers from the right and left vagus nerves. The anterior vagal trunk: a. It is formed in the thorax from the left vagus nerve. b. enters the abdomen on the anterior surface of the esophagus. c. The trunk divides into branches supply the anterior surface of the stomach. d. A large hepatic branch passes up to the liver, and from this a pyloric branch passes down to the pylorus. The posterior vagal trunk a. Formed in the thorax from the right vagus nerve. b. Enters the abdomen on the posterior surface of the esophagus. c. Supply the posterior surface of the stomach. d. the intestine as far as the splenic flexure and to the pancreas. The sympathetic innervation of the stomach carries: a. Pain-transmitting nerve fibers b. The pyloric sphincter receives motor fibers from the sympathetic system and inhibitory fibers from the vagi.  Small Intestine It is the longest part of the alimentary canal Extends from the pylorus of the stomach to the ileocecal junction. Digestion and food absorption takes place in the small intestine. It is divided into duodenum, jejunum, and ileum.  Duodenum a. It is situated in the epigastric and umbilical regions b. It is a C-shaped tube, about 10 in. (25 cm) long. c. It receives the openings of the bile and pancreatic ducts. d. It curves around the head of the pancreas. e. Its first inch (2.5 cm): 1. Resembles the stomach, covered with peritoneum 2. The lesser omentum attached to its upper border and the greater omentum attached to its lower border 3. The lesser sac lies behind it. 4. The remainder of the duodenum is retroperitoneal  Parts of the Duodenum First Part of the Duodenum It begins at the pylorus and runs on the transpyloric plane at the level of the 1st lumbar vertebra.  Second Part of the Duodenum a. It runs vertically downward in front of the hilum of the right kidney. b. halfway its medial border, the bile duct and the main pancreatic duct pierce the duodenal wall. c. They unite to form the ampulla that opens on the summit of the major duodenal papilla. d. The accessory pancreatic duct opens a little above on the minor duodenal papilla.  Third Part of the Duodenum a. The third part of the duodenum runs horizontally to the left on the subcostal plane b. Passing in front of the vertebral column and following the lower margin of the head of the pancreas. Fourth Part of the Duodenum a. The fourth part of the duodenum runs upward and to the left to the duodenojejunal flexure. b. The flexure is held in position by a peritoneal fold, the ligament of Treitz, which is attached to the right crus of the diaphragm.  Mucous Membrane and Duodenal Papillae In the first part of the duodenum, it is smooth. In the remainder of the duodenum, has the plicae circulares. The bile duct and the main pancreatic duct open into the major duodenal papilla, The accessory pancreatic duct by a smaller papilla above the major duodenal papilla. Arteries Blood Supply The upper half by the superior pancreaticoduodenal artery, a branch of the gastroduodenal artery. The lower half by the inferior pancreaticoduodenal artery, a branch of the superior mesenteric artery. Veins The superior pancreaticoduodenal vein drains into the portal vein. The inferior vein joins the superior mesenteric vein.  Lymph Drainage a. The lymph vessels follow the arteries b. Upward via pancreaticoduodenal nodes to the gastroduodenal nodes and to the celiac nodes c. Downward via pancreaticoduodenal nodes to the superior mesenteric nodes around the origin of the superior mesenteric artery. Nerve Supply Sympathetic and parasympathetic (vagus) nerves from the celiac and superior mesenteric plexuses.  Jejunum and Ileum a. The jejunum and ileum measure about (6 m) long. b. The upper two fifths of this length make up the jejunum. c. The jejunum begins at the duodenojejunal flexure, and the ileum ends at the ileocecal junction. d. The coils of jejunum and ileum are mobile and are attached to the posterior abdominal wall by the mesentery of the small intestine. mesentery of the small intestine a. The long free edge of the fold encloses the mobile intestine. b. Its root is along the left side of the 2nd lumbar vertebra to the region of the right sacroiliac joint. c. The root permits the entrance and exit of artery and vein, lymph vessels, and nerves between the two layers of peritoneum forming the mesentery.  Difference between jejunum and ileum jejunum ileum coiled in the upper part of the peritoneal cavity below in the lower part of the cavity and in the pelvis the left side of the transverse mesocolon wider bored, thicker walled, and redder not The jejunal wall is thicker because the permanent in the upper part they are smaller and more widely plicae circulares separated and in the lower part they are absent The jejunal mesentery is attached to the posterior the ileal mesentery is attached below and to the right abdominal wall above and to the left of the aorta of the aorta The jejunal mesenteric vessels form one or two The ileum receives short terminal vessels that arise arcades, with long branches passing to the intestinal from a series of three or four or even more arcades. wall. At the jejunal end of the mesentery, the fat is deposited At the ileal end of the mesentery, the fat is deposited near the root from the root to the intestinal wall. (Peyer’s patches) are present in the mucous membrane of the lower ileum along the antimesenteric border.  Blood Supply Arteries a. branches of the superior mesenteric artery. b. The intestinal branches arise from the left side of the artery and run in the mesentery to reach the gut. c. They anastomose with one another to form a series of arcades. d. The lowest part of the ileum is also supplied by the ileocolic artery. Veins The veins drain into the superior mesenteric vein. Lymph Drainage The lymph vessels pass through many intermediate mesenteric nodes and finally reach the superior mesenteric nodes, which are situated around the origin of the superior mesenteric artery. Nerve Supply The nerves are derived from the sympathetic and parasympathetic (vagus) nerves from the superior mesenteric plexus. Case discussion A 15-year-old boy complaining of pain in the lower right part of the anterior abdominal wall was seen by a physician. He had a furred tongue and was extremely tender in the lower right quadrant. The abdominal muscles in that area were found to be firm (rigid) on palpation and became more spastic when increased pressure was applied (guarding). A diagnosis of acute appendicitis was made. Questions 1- Abdominal part of esophagus: A- It enter the abdomen through opening in the right crus of diaphragm B- left and right vagi lie on its anterior and posterior surfaces C- Its arterial supply is the hepatic artery D- Its vein drains in the portal vein 2- Stomach: A- The fundus lies to the left of the cardia B- The body extends from the cardiac opening to the incisora angularis C- The lesser curvature is attached to the porta hepatis D- Pylorus runs in the subcostal plane 3- Small intestine: A- The duodenum lies in the epigastric and umbilical regions B- The 1st inch of duodenum resemble the stomach C- The 1st part of the duodenum is related anteriorly to the gall bladder D- 1st part of duodenum is related superiorly to the caudate lobe 4- 4th part of duodenum: A- It forms the duodenojejunal flexure B- The flexure is hold by ligamentum of Treitz to the left crus of diaphragm C- It lies posterior to the aorta D- It lies anterior the root of mesentery References Clinical anatomy by regions / Richard S. Snell. – 9th ed. Gray's Anatomy, 40th Edition By Susan Standring, PhD, DSc, FKC