Right: Ventral view of buccal mass; outer layer of mass removed to show buccal nerve cord and ganglia on odontophore. Anterior of mass towards right of image.
Left: Dorsal view of buccal mass with main nerve ring pulled back and flattened; oesophagus removed from within nerve ring.
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. Each ganglion innervates a usually proximate, specific part of the body. The cerebral ganglia on the nerve ring connect to the ocular tentacles, eyes and other parts of the head. There is a subsidiary ring with ganglia around the buccal mass to control its feeding movements. The pedal ganglia on the ventral part of the nerve ring connect to the foot.
1: main nerve ring of the nervous system.
2: lobed right cerebral ganglion.
3: two nerve cords connecting cerebral ganglion to right tentacles.
4: left pedal ganglion, ventral surface twisted into view, with multiple nerve cords for control of the foot.
5: left cartilaginous bolster of odontophore partly exposed by removal of outer layer of buccal mass.
6: nerve cord encircling the odontophore.
7: ganglion on nerve cord encircling the odontophore.
8: posterior end of radula sac (radula removed).