Stomach: Anatomy & Physiology

Anatomy

Layers

  • Mucosa
  • Submucosa
  • Muscularis Propria (Inner Oblique, Middle Circular, Outer Longitudinal)
  • Serosa

Structures

  • Incisura Angularis – Abrupt Angle of the Lesser Curvature to the Right
    • Represents the Transition from Body to Antrum
  • Angle of His – Abrupt Angle from the Fundus to the Left Margin of the Esophagus

Stomach 1

Blood Supply

  • Pylorus
    • Gastroduodenal Artery (GDA) – From Common Hepatic
  • Lesser Curvature
    • Left Gastric – From Celiac Trunk
    • Right Gastric – From Proper Hepatic
  • Greater Curvature
    • Short Gastrics – From Splenic
    • Left Gastroepiploic – From Splenic
    • Right Gastroepiploic – From GDA
    • Arc of Barkow – Anastomosis of the Right & Left Gastroepiploic Arteries
      • Has Multiple Ascending Branches That Supply the Transverse Colon

Blood Supply 1

Blood Supply (Back) 1

Nerves

  • Anterior Vagal Trunk
    • Origin: Left Vagus
    • Smaller, Buried Within Fiber of Esophageal Wall
    • Hepatic Branch
      • First Branch
      • To Liver
  • Posterior Vagal Trunk
    • Origin: Right Vagus
    • Larger, About 1-2 cm Separation from Esophageal Wall
    • Criminal Nerve of Grassi
      • First Branch
      • To Fundus
    • Celiac Branch
      • To Celiac Plexus
  • Branches of Both Anterior & Posterior
    • Anterior/Posterior Nerves of Latarjet (Gastric Divisions)
      • Continuations Along Lesser Curvature
      • Posterior Division is Shorter than the Anterior Division & Usually Does Not Reach the Duodenum
    • “Crow’s Foot”
      • Distal Branches to Pyloric Antrum

Stomach Nerves 2

Lymph Node Stations – Japanese Classification

  • 1: Right Pericardial Stomach
  • 2: Left Pericardial Stomach
  • 3: Lesser Curvature
  • 4: Greater Curvature
    • 4sa: Short Gastrics
    • 4sb: Left Gastroepiploic
    • 4d: Right Gastroepiploic
  • 5: Suprapyloric
  • 6: Infrapyloric
  • 7: Along Left Gastric Artery
  • 8: Along Common Hepatic Artery
    • 8a: Anterosuperior CHA
    • 8p: Posterior CHA
  • 9: Celiac Axis
  • 10: Splenic Hilum
  • 11: Splenic Artery
    • 11p: Proximal Splenic Artery
    • 11d: Distal Splenic Artery
  • 12: Hepatoduodenal Ligament
    • 12a: Hepatic Artery
    • 12b: Bile Duct
    • 12p: Behind Portal Vein
  • 13: Posterior Surface of the Pancreatic Head
  • 14: Root of the Mesentery
    • 14a: SMA
    • 14v: SMV
  • 15: Paracolonic
  • 16: Paraaortic
    • 16a1: Aortic Hiatus
    • 16a2: Celiac to Left Renal
    • 16b1: Left Renal to IMA
    • 16b2: IMA to Bifurcation
  • 17: Anterior Surface of Pancreatic Head
  • 18: Inferior Margin of Pancreas
  • 19: Infradiaphragmatic
  • 20: Esophageal Hiatus
  • 110: Paraesophageal in Lower Thorax
  • 111: Supradiaphragmatic
  • 112: Posterior Mediastinum

Lymph Node Stations 3

Physiology

Peristalsis

  • In the Stomach it Only Occurs in Antrum
  • From Interstitial Cells of Cajal (Pacemaker Cells)

Stomach Secretion & Hormones

  • Cardia
    • Cardiac Glands
      • Secrete: Mucous
  • Fundus & Body
    • Chief Cells
      • Secrete: Pepsinogen
        • HCl Converts to Active Pepsin (Protease – Start Proteolysis)
    • Parietal Cells
      • Secrete:
        • HCl (H+)
          • Final Pathway: H/K ATPase (Where PPI’s Act)
        • Intrinsic Factor
          • Binds B12
          • Absorbed in Ileum
        • Stimulated By: Acetylcholine (Vagus), Gastrin & Histamine
        • Inhibited By: Somatostatin, Prostaglandin, Secretin & CCK
  • Antrum & Pylorus

GI Microflora

Stomach Microflora

  • Mostly Sterile (Due to High Acidity)
  • Some Bacteria and Yeast Present

Small Intestine Microflora

  • Still Trace in Proximal 2/3 (Due to Proximity to Stomach Acids)
  • Mostly GPC
  • In Distal Aspect – Some GPR & GNR; Begin to Resemble Large Intestine

Large Intestine Microflora

  • 99.9% Anaerobes
  • Some GNR & GPR
  • Bacteria Compose 60% of Feces Dry Mass

References

  1. Gray H. Anatomy of the Human Body (1918). Public Domain.
  2. Murakami H, Matsumoto H, Kubota H, Higashida M, Nakamura M, Hirai T. Evaluation of electrical activity after vagus nerve-preserving distal gastrectomy using multichannel electrogastrography. J Smooth Muscle Res. 2013;49:1-14. (License: CC BY-NC-ND-4.0)
  3. Dikken JL, van Sandick JW, Maurits Swellengrebel HA, Lind PA, Putter H, Jansen EP, Boot H, van Grieken NC, van de Velde CJ, Verheij M, Cats A. Neo-adjuvant chemotherapy followed by surgery and chemotherapy or by surgery and chemoradiotherapy for patients with resectable gastric cancer (CRITICS). BMC Cancer. 2011 Aug 2;11:329. (License: CC BY-2.0)