A general account of the formation and distribution of the spinal nerves has been given (see p. 29).

That account described the formation of each nerve by the union of dorsal and ventral roots and its later division into dorsal and ventral primary rami, which diverge on passing through the intervertebral foramen (Figure 8-55). The rather consistent pattern of distribution of the dorsal rami may be represented by a single description; impor­tant regional features of the ventral rami require sepa­rate attention.