Instead of a single brain, C. hortensis, like other gastropods, has a series of ganglia (nerve knots) on a nerve cord that runs in a ring around the oesophagus with a dorsal and a ventral longitudinal extension towards the posterior on each side of the body . Each ganglion innervates a usually proximate, specific part of the body. The lobed cerebral ganglia on the nerve ring connect to the ocular tentacles,anterior tentacles and other parts of the head. The pedal ganglia on the ventral part of the nerve ring connect to the foot. Other regions of the body are connected to ganglia on the longitudinal extensions towards the posterior.
In the image, the nerve ring has been removed from the body, flattened and twisted to bring it and both pedal ganglia and cerebral ganglia into full view.
1: nerve ring.
2: lobed cerebral ganglion.
3: nerve cords to tentacles.
4: nerve cords to head.
5: pedal ganglia.
6: multiple nerve cords to foot.
7: longitudinal nerve cord extension from nerve ring towards posterior of body (displaced by dissection).