Stomatogastric ganglion

Anatomy

The neurons comprising the stomatogastric ganglion have cell bodies located dorsal to the stomach within the lumen of the ophthalmic artery. Most are motor neurons, with neurites that exit through motor nerves and innervate the muscles of the gastric mill and pylorus. These STG motor neurons also form direct synaptic connections with one another. In crabs and lobsters, in which it has been well-studied, the stomatogastric ganglion is a collection of approximately 25-30 neurons. The circuit varies slightly between different crustacean species and between individuals of the same species, but most of the neurons are conserved, and most stomatogastric muscles are innervated by just one motor neuron. The electrical and chemical synaptic connections between all of the STG neurons have been fully mapped and characterized, forming a complete wiring diagram (also called a connectome).