Longitudinal nerve trunks connect the nerve concentration in the esophageal region to the nerve concentration in the anal region. The anterior nerve concentration is the nerve ring or circumesophageal commissure. The ring is a commissure for the dorsal, ventral, and lateral ganglia which are usually in pairs. The longitudinal nerve trunks arise from these ganglia (Figure 22.12). The ventral ganglia and the ventral nerve trunk are the largest examples of each type of structure. Amphidial nerves proceed anteriorly from the lateral ganglia. Papillary nerves arise directly from the nerve ring and innervate cephalic sensory papillae around the mouth.