Correspondence

I Read With great interest the paper, ‘The eagle and the serpent’ by Roderick Peters (this Journal, October 1987, Vol. 32, No. 4) — especially the links Dr Peters makes between the eagle and the central nervous system (CNS) and the serpent and the autonomic nervous system (ANS). Indeed, it gave me an ‘ANS’ response along my spine so neatly did it appear to crystallise symbol and body relationship.

But one doubt crossed my cerebral cortex in that I had long ago learned of another system called the peripheral nervous system and that there was more to both CNS and ANS—and where did this fit? I searched my anatomy and physiology textbooks and doubt grew. Could we then make use of this for further dialogue?

Indeed, it does appear that there are basically two systems, but these are the central nervous system within the skull and vertebral column, and peripheral nervous system outside of these. Both structurally and functionally these divisions are artificial and ‘the basic unity of the nervous system must never be forgotten’. Its study must perforce be simplified by the examination of different systems and regions. Part of it is concerned with the maintenance within of conditions suitable for life and part is concerned with the reactions to cope with environmental conditions. These are the visceral (or autonomic) system as interoceptive, and the somatic system as exteroceptive and proprioceptive respectively. And each has both central and peripheral components.

The caduceus symbol (on page 366) bears this out: the wings and staff are equivalent to the central and peripheral somatic nervous system; the snake head and tail equivalent to the central and peripheral visceral nervous system, (a foursome plan within the two broad groups). Was Kekulé explaining away ‘his’ curled snake dream in the link with his benzene ring hunch?

The distinction between somatic and visceral corresponds approximately to the distinction between the body wall (muscles, bone and other structures derived