Crab Stomatogastric Nervous System

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There are important distinctions between the stomatogastric nervous systems (STNS) of decapod crustaceans. This page is an introduction to the STNS of the crab, Cancer borealis.

Diagram showing all of the nerves and ganglia in the crab stomatogastric nervous system.


  • STG: Stomatogastric ganglion
    • A midline ganglion containing about 30 neurons. Most are motor neurons
  • CoG: Commissural Ganglion
    • sometimes called Circumoesophageal Ganglion
    • bilaterally symmetric ganglia each contains over 100 neurons
  • OG: Oesophageal Ganglion
    • sometimes abbreviated OeG
    • a small midline ganglion that contains neurons that project to the STG


Diagram of the musculature of the crab foregut showing the innervation pattern for each motor neuron
  • dvn: dorsal ventricular nerve
    • major output nerve of the STG
  • ion: inferior oesophageal nerve
    • connects CoG to OG
  • ivn: inferior ventricular nerve
    • connects OG to brain (supra-oesphageal ganglion)
  • lvn: lateral ventricular nerve
    • branches from posterior dvn
  • mvn: medial ventricular nerve
    • contains STG axons:
      • IC
      • VD
  • son: superior oesophageal nerve
    • connects CoG to OG
  • stn: stomatogastric nerve
    • main input nerve to STG with axons of descending neurons from CoG and OG
    • contains axons ascending neurons:


basic circuitry of the crab stomatogastric ganglion. Neurons that are primarily pyloric are shown in red. Neurons that are primarily in the gastric mill are in blue. Those that are in both CPGs are shown as shaded.

There is extensive electrical coupling in the crab STG. Many neurons participate in both the pyloric and gastric mill motor patterns. Yet it is useful to list the primary affiliations of the neurons.

Pyloric Neurons

  • AB - Anterior Burster
  • PD - Pyloric Dilator
  • LP
  • PY
  • IC
  • VD
  • LPG - LPG is generally considered a gastric mill neuron in most species, but has a strong pyloric activity.

Gastric Mill Neurons

  • Int1
  • DG
  • LG
  • MG
  • GM
  • AM

Intracellular recordings from each of the pyloric neurons in the crab STG. Intracellular recordings from each of the gastric mill neurons in the crab STG. On the left side, the activity pattern when the gastric mill is quiescent and the right side is when it is active.