Wed Sept 9th, 2015: Esophagus, Stomach, Duodenum, Peritoneum Christopher Ramnanan, Ph.D. Describe location of the esophagus and recognize the two sphincters and identify the 3 constrictions. Identify the anatomical features of the stomach and duodenum. Review the principal vascular and nerve supply of the esophagus and gastroduodenal area. Review the gross anatomical relationships of the stomach, duodenum and surrounding structures. Define peritoneal covering of the abdominal viscera.

C6 Vertebral Level as a Landmark C6 Cricoid cartilage Larynx Trachea Pharynx SuperiorConstrictor MiddleConstrictor InferiorConstrictor Esophagus At the C6 level, progressing inferiorly: -Larynx ends, and the trachea begins -Pharynx ends, and the esophagus begins -Location of the pharyngoesophageal sphincter and cricoid cartilage

Esophagus Overview Abdominal Thoracic Cervical Three parts: Cervical/Pharyngoesophageal* (Upper Esophageal Sphincter) Thoracic (left bronchus/ aortic arch) Diaphragmatic* (Lower Esophageal Sphincter) C6 T4 T10 Three constrictions (Two sphincters*) :

Cricoid cartilage Inferior Pharyngeal Constrictor (2 parts) Pharyngoesophageal Constriction/Sphincter (Upper Esophageal Sphincter) Esophagus Pharyngoesophageal Constriction (Sphincter) Esophageal musculature: -Outer layer longitudinal -Inner layer circular -Transition from pharynx leaves areas of relative muscular deficiencies -ex. Killian’s dihiscence: predisposition to Zenker’s diverticulum Thyropharyngeus Cricopharyngeus Killian’s Dihiscence

Diaphragmatic Constriction (Lower Esophageal Sphincter, LES) Diaphragmatic constriction Cardia of stomach Esophagus Clinical Anatomy: Hiatal Hernia can weaken LES function, cause predisposition to gastroesophageal reflux disease (GERD)

Esophageal Arterial Supply Abdominal Region: Esophageal br. of the left gastric artery (itself a branch of the celiac trunk) Thoracic Region: *Esophageal arteries from the thoracic aorta Cervical Region: *Esophageal br. of the inferior thyroid a. *These arteries are difficult to observe in lab

Abdominal Region: *Esophageal br. drain mainly to tributaries of the portal vein (left gastric v.) Thoracic Region: blood drains to the azygos system (systemic) Cervical Region: *Esophageal br. of the inferior thyroid v. Azygos Vein Hemiazygos V. Accessory Hemiazygos V. Note: Submucosal veins in distal esophagus can drain either portally or systemically (discussed further in Liver Lab); rupture can be life-threatening Esophageal Venous Plexus Drainage *Veins difficult to observe grossly

Innervation of the Esophagus Most of the esophagus (all except for the most proximal part) is under autonomic control mediated by esophageal plexus (peristalsis, arterial vasoconstriction, glandular secretion) Sympathetic supply (General): IML T1-T10  Sympathetic trunk Parasympathetic supply: Left Vagus Nerve  Esophageal Plexus  Anterior Vagal Trunk Right Vagus Nerve  Esophageal Plexus  Posterior Vagal Trunk

Peritoneum: the serous membrane that lines the walls of (parietal; sensitive to pain), and organs in (visceral), the abdomen Peritoneal cavity: potential space (capillary-thin) between visceral and parietal layers of peritoneum; 2 compartments that communicate via the omental foramen: Greater sac and Lesser sac (Omental bursa) Abdominal Cavity: Sum of Peritoneal Cavity, Retroperitoneal Cavity, and Intraperitoneal Organs Mesentery: double-layer of peritoneum, usually tethering intraperitoneal organs to the body wall (vasculature travels to intraperitoneal organs in the mesentery) Omentum: mesentery associated with stomach (Greater and Lesser) Peritoneal Ligaments: Thickened parts of mesentery/omentum connecting two organs The Peritoneal Cavity: Terminology and Overview

Intraperitoneal structures: -Enveloped with peritoneum; tethered to body wall via mesenteries (protrudes forward into abdominal cavity; mobile; possible herniation) Stomach Stomach, Liver, Spleen, 1 st part of duodenum 1 st part of duodenum, tail of pancreas, transverse colon, sigmoid colon Retroperitoneal structures: -Only covered with peritoneum on anterior aspect; pushed against back body wall in adult anatomy; immobile Abdominal Part of Esophagus, 2 nd -4th parts of duodenum Abdominal Part of Esophagus, 2 nd -4th parts of duodenum, most of pancreas, ascending and descending colon, rectum Aorta, IVC, kidneys, ureters, suprarenal glands, autonomic nerves

Infracolic compartment (next lab) Infracolic compartment (next lab): subdivided into left and right areas by Root of the Mesentery (small intestine); note the left and right paracolic recesses Supracolic compartment (today) Omental Foramen opening into Lesser Sac Transverse Mesocolon separates Greater Sac into supracolic and infracolic compartments

The Stomach, Greater Omentum and Lesser Omentum Duodenum Lesser CurvatureLesser Omentum: Hepatogastric Ligament Hepatoduodenal Ligament Greater Curvature In lab today: ID omental foramen Greater Omentum: Three Ligaments (next slide)

Greater Omentum: Ligaments Gastrophrenic Lig. Gastrosplenic Lig. Gastrocolic Lig. Gastrocolic Lig. (posterior aspect that attaches to transverse mesocolon) These ligaments may be difficult to appreciate on the specimens

Stomach: Isolated View Initial part of stomach; inflow region Superior dilation; separated from cardia by cardial notch Major part of stomach Pyloris: funnel-shaped outflow region Internally: rugae (collapsable folds)

1st part (Superior) 2 nd part (Descending) 3rd part (Inferior) 4th part (Ascending) Duodenum: Isolated View Note: -1 st part intraperitoneal (IP), has mesentery; 2 nd -4 th parts retroperitoneal -3 rd part runs posterior to SMA -transition to jejunum (mesentery, IP) at duodenojejunal flexure suspensory ligament (Ligament of Treitz marked by suspensory ligament (Ligament of Treitz): clinical landmark in assessing malrotation of the gut and in differentiating upper vs. lower GI bleeds)

Duodenum: Internal Aspect Note: -1 st part smooth; 2 nd -4 th part rugose appearance -2 nd part contains major duodenal papilla (drainage of common bile duct and main pancreatic duct); signifies transition from foregut to midgut Major duodenal papilla

ArteryVeinSymp. Nerve Supply (GENERAL) PS Nerve Supply FOREGUT Liver, Stomach, gallbladder, spleen, proximal duodenum, pancreas Celiac Trunk Tributaries of the Portal Vein Dominant: Greater Splanchnic (T6-T9) Vagus MIDGUT Distal duodenum, jejunem, ileum, ascending colon, transverse colon SMASMVDominant: Lesser (T10/T11) and Least (T12) Splanchnic Vagus HINDGUT Descending colon, sigmoid colon, rectum, anus IMAIMVLumbar Splanchnic (L1/L2) Pelvic Splanchnic (S2-S4) Abdominal GI tract: Overview

Arterial Supply of Gastroduodenal Area Celiac Trunk Splenic A. Common Hepatic A. Left Gastric A. Celiac Trunk: Artery of the Foregut Right Gastric A. Proper Hepatic A. Gastroduodenal A. Right and Left Gastro-omental A. Short Gastric A.

Gastroduodenal A. Superior Mesenteric Artery (SMA): Artery of the Midgut; supplies Inferior Pancreaticoduodenal A. (Ant/Post) R. Gastro-omental A. Superior Pancreaticoduodenal A. (Anterior/Posterior)

Venous Drainage of Gastroduodenal Area Portal Vein Tributaries: Veins of the Foregut Portal Vein SMV: Vein of the midgut Splenic V. IMV: Vein of the hindgut

Nerve Supply of the Gastroduodenal Area (Conceptual) Greater Splanchnic N. Superior Mesenteric Ganglion Lesser Splanchnic N. Celiac Ganglia (associated with foregut sympathetics) (Foregut and Midgut Parasympathetics) Ant. And Post. Vagal Trunk (Foregut and Midgut Parasympathetics) Least Splanchnic N. Associated with Midgut Sympathetics Associated with Foregut Sympathetics

Autonomics of abdominal foregut, midgut, hindgut Parasympathetic supply: -Vagus nerve (foregut+midgut; up to left colic flexure) -Pelvic splanchnics S2-S4 (hindgut) -Synapses happen at organ wall Sympathetic supply: -Originates from T1-L2 in spinal cord IML -Travels to sympathetic trunk, leaves medially -Greater, lesser, least and lumbar splanchnic nerves synapse at prevertebral ganglia associated with major arteries of foregut, midgut, hindgut -Postsynaptic fibers then head to their organs by riding with arteries

Visceral Pain Lines Heart (Cardiopulmonary Splanchnic Nn., T1- 6) Thoracic Pain Line: ~plane of sternal angle Pelvic Pain Line: ~ plane of lower extent of peritoneum Note: TESTES Testes refer with sympathetics due to embryological origins (pelvic lecture) Generally, Abdominal GI organ pain refers with sympathetics

Foregut T6-T9 Midgut T10-T12 Hindgut L1 T10 T11 T12 L1 T9 T8 T7 T6 T5 T4 GI Referred Pain: Continued Pain from visceral organs is poorly localized, and the CNS usually interprets such pain incorrectly as coming from the corresponding dermatome (body wall)

Right Hypo- chondriac Left Hypo- chondriac Epigastric Umbilical Suprapubic Right Lumbar Left Lumbar Right Inguinal Left Inguinal Foregut pain T6-T9 dermatome GI Referred Pain: General Map Midgut pain T10-T12 dermatome Hindgut pain L1 dermatome Right Upper Right Lower Left Upper Left Lower We will revisit the concept of referred pain of GI viscera over next few weeks

LAB 2 CHECKLIST – ESOPHAGUS, STOMACH, DUODENUM, PERITONEUM ESOPHAGUS 3 Constrictions: -C6: Cervical/pharyngoesophageal (upper esophageal sphincter) -Thyropharyngeus -Cricopharyngeus -Inferior pharyngeal constrictor -Killian’s Dehiscence -T4: Thoracic (left bronchus/aortic arch) -T10: Diaphragmatic (lower esophageal sphincter) Vasculature: -Cervical -Esophageal br. of inferior thyroid a. and v. -Thoracic -Esophageal a. -Azygos v. -Hemiazygos v. -Accessory hemiazygos v. -Abdominal -Esophageal br. of left gastric a. -Esophageal br. drain to left gastric v. and inferior phrenic v. Innervation: -Sympathetics: IML T1-T10, sympathetic trunk -Parasympathetics: Left and Right vagus n. -Esophageal plexus -Ant. vagal trunk and post. vagal trunk PERITONEAL CAVITY -Peritoneum -Peritoneal cavity vs. abdominal cavity -Omental foramen -Greater sac -Lesser sac (omental bursa) -Intraperitoneal vs. retroporitoneal -Mesentery -Greater omentum -Gastrophrenic lig. -Gastrosplenic lig. -Gastrocolic lig. -Lesser omentum -Hepatogastric lig. -Hepatoduodenal lig. -Peritoneal ligaments -Transverse mesocolon -Supracolic compartment -Infracolic compartment NB: Items italicized are conceptual, those denoted with a * are FYI ARTERIAL SUPPLY Celiac Trunk -Common hepatic a. -Proper hepatic a. -Gastroduodenal a. -Right gastro-omental a. -Superior pancreaticoduodenal a. (anterior/posterior) -Right gastric a. -Left gastric a. -Splenic a. -Left gastro-omental a. -Short gastric a. Superior Mesenteric A. -Inferior pancreaticoduodenal a. (anterior/posterior) STOMACH -Cardia -Fundus -Body -Pyloris (antrum and canal) -Rugae DUODENUM -1 st part (superior) -2 nd part (descending) -3 rd part (inferior) -4 th part (ascending) -Duodenojejunal flexure -Suspensory ligament (Ligament of Treitz) -Major duodenal papilla VENOUS DRAINAGE -Portal v. and tributaries -Splenic v. -Superior mesenteric v. -Inferior mesenteric v. INNERVATION -Anterior and posterior vagal trunk -Greater splanchnic n. -Celiac ganglia -Lesser splanchnic n. -Least splanchnic n. -Superior mesenteric ganglion -Referred pain for foregut structures