A general account of the formation and distribution of the spinal nerves has been given (see p. 27).

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 branches or rami, which diverge from each other on passing through the intervertebral foramen (Fig. 8.55). The term rami rather than the general term branch is used here to refer to the most proximal dorsal and ventral branch of each spinal nerve, to avoid confusion with further divisions of these nerves. 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.