Ganglion that lies at the anterior limit of the ventral nerve cord, near the ventral ganglion and nerve ring in the head posterior to the excretory pore. It is open and continuous with the region containing the motoneurons of the ventral cord. In the early L1 this ganglion holds 12 neuron cell bodies plus one neuroblast (Sulston and Horvitz, 1977; White et al., 1986). In the adult animal, the ganglion holds 20 neuron cell bodies.
The left and right lumbar ganglia lie behind the pre-anal ganglion in the tail, in lateral positions. Each contains 12 neuron cell bodies that send most of their neuronal processes into the ventral nerve cord via lumbar commissures and the pre-anal ganglion. There is no local neuropil in these ganglia in the hermaphrodite, instead they form most synapses in the pre-anal ganglion. Most lumbar neurons have sensory functions. In the adult male tail, these two ganglia gain many additional neurons and have some local neuropil. The lumbar neurons lie in close association with the lateral hypodermis, and most are posterior to the anus.