Wed Sept 9th, 2015: Esophagus, Stomach, Duodenum,

Peritoneum

Christopher Ramnanan, Ph.D.cramnana@uottawa.ca

• 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

C6Cricoid 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 PharyngealConstrictor(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

CricopharyngeusKillian’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, Liver, Spleen, 1st 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, 2nd-4th parts of duodenum, most of pancreas, ascending and descending colon, rectum

Aorta, IVC, kidneys, ureters, suprarenal glands, autonomic nerves

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 LigamentHepatoduodenal Ligament

Greater Curvature

In lab today: ID omental foramen

Greater Omentum:Three Ligaments (next slide)

Greater Omentum: Ligaments

Gastrophrenic Lig.

Gastrosplenic 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)

2nd part (Descending)

3rd part (Inferior)

4th part (Ascending)

Duodenum: Isolated View

Note: -1st part intraperitoneal (IP), has mesentery; 2nd-4th parts retroperitoneal-3rd part runs posterior to SMA-transition to jejunum (mesentery, IP) at duodenojejunal flexuremarked 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: -1st part smooth; 2nd-4th part rugose appearance

-2nd part contains major duodenal papilla (drainage of common bile duct and main pancreatic duct); signifies transition from foregut to midgut

Major duodenal papilla

Artery Vein Symp. 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

MIDGUTDistal duodenum, jejunem, ileum, ascending colon, transverse colon

SMA SMV Dominant: Lesser (T10/T11) and Least (T12) Splanchnic

Vagus

HINDGUTDescending colon, sigmoid colon, rectum, anus

IMA IMV Lumbar 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 AreaPortal 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)

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 (CardiopulmonarySplanchnic 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

T8T7

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)

RightHypo-chondriac

LeftHypo-chondriac

Epigastric

Umbilical

Suprapubic

RightLumbar

LeftLumbar

RightInguinal

LeftInguinal

Foregut painT6-T9 dermatome

GI Referred Pain: General Map

Midgut painT10-T12 dermatome

Hindgut painL1 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

ESOPHAGUS3 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- 1st part (superior) - 2nd part (descending) - 3rd part (inferior) - 4th 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