Structure of the Dorsal Horn

Abstract

This chapter will take as its primary mission the description of the structure of the dorsal horn, in particular laminae I–VI of Rexed (Fig. 3.1). The format will be to describe each of the laminae in turn, with interludes for issues that are not strictly related to the structure of a particular lamina. This format can be justified because almost all recent studies on the anatomy and physiology of the dorsal horn have used the laminae as landmarks, and it will be one of the purposes of this chapter to show to what extent the laminae are meaningful, not just in terms of being landmarks, but in terms of the fundamental organization of the spinal cord. Three relatively arbritrary cut-off points were chosen to keep the length of this chapter within reasonable bounds. First, only the dorsal six laminae are considered. Second, although the primary afferent input to each of the laminae is considered, the equally important descending input is not. Third, the considerations of dorsal horn structures are primarly restricted to studies on chick, rat, cat, monkey, and man.