ganglion

There must therefore be an isolated ganglion in front and two ganglia, close to each other, about two-fifths of an inch back.

Do they actually wound with their dirks the ganglion whose influence is to be done away with?

Do they confine themselves to lodging their drop of poison on the ganglion, or at all events in its immediate neighbourhood?

A cinder enters the eye, the report reaches a ganglion, a motor impulse is sent forth, and the eyelid closes.

A single ganglion represents the nervous system, placed between the two apertures.