These tracts run longitudinally through the cord, some descending to relay information from the brain to the spinal cord, others ascending to transmit information to the brain. Pathways also transmit information between different levels of the spinal cord.Groups of afferent neuron axons that enter the spinal cord from the peripheral nerves enter on the dorsal side of the cord via the dorsal roots. Small bumps on the dorsal roots, the dorsal root ganglia, contain the cell bodies of these afferent neurons.The axons of efferent neurons leave the spinal cord on the ventral side via the ventral roots. A short distance from the cord, the dorsal and ventral roots from the same level combine to form a spinal nerve, one on each side of the spinal cord.