A nerve ring surrounds the oesophagus, it has a pair of cerebral ganglia dorsolaterally, and a ventral ganglion below the oesophagus. Small nerves are given out anteriorly from the ganglia.
Posteriorly three pairs of longitudinal nerve cords arise from the ganglia, a dorsal, a lateral, and a ventral pair of nerve cords.
The lateral nerve cords are best developed and they run to the posterior end.
Nerve cords are connected by transverse commissures and they give out many small branches, some of which form plexuses. The nerve cells are mostly bipolar.
Due to parasitic life, sense organs are lost in adult Fasciola.