The Nematoda phylum, also called the roundworm, is divided into Dorylaimia, Enoplea, Secernetea, and Chromodorea. Their nervous system contains four peripheral nerves that run through the body on the dorsal, ventral, and lateral surfaces. The nerves lie under the cuticle but between the muscle cells. The dorsal nerves are responsible for movement, the lateral nerves are sensory, and the ventral nerves help with both movement and the senses. In the back end of the Nematoda a bunch of branched nerves form a ring around the pharynx and serve as a brain. Nerves run from the ring to the head to supply the body with sensory organs. The body of the Nematoda is covered with sensory papilla and bristles that provide a sense of touch. Nematoda are very sensitive to touch and when touched they often move away as fast as possible.