These sensory and motor nerve roots unite to create the 31 spinal nerves, each named for the individual vertebra from which it exits. The spinal nerves further divide into anterior and posterior rami.

C. S. Sherrington, Experiments in Examination of the Peripheral Distribution of the Fibres of the Posterior Roots of Some Spinal Nerves. [Abstract], Proceedings of the Royal Society of London, Vol. 52 ...