ON THE PARASYMPATHETIC (SPINAL PARASYMPATHETIC) FIBRES IN THE DORSAL ROOTS AND THEIR CELLS OF ORIGIN IN THE SPINAL CORD

¹ Medical Clinic of the Tokyo Imperial University

1. Every spinal segment has parasympathetic fibres in its dorsal roots, their cells of origin (nuclei) lying between the ventral horn and the substantia gelatinosa of the dorsal horn. We designate this system of autonomic fibres "the spinal parasympathetic."

2. The spinal parasympathetic fibre, s consist chiefly of fine medullated fibres, 3 microns or less in diameter.

3. Any fine medullated fibres in the dorsal roots, with the exception of those in the sacral region (from the IInd sacral down), belong for the most part to the spinal parasympathetic system.

4. The number of the parasympathetic fibres is about 40 per cent. of the total fibres in a dorsal root.

5. From the IInd sacral segment downwards the dorsal roots contain a fair number of fine medullated sensory fibres.

6. The spinal parasympathetic fibres comprise vasodilators (some destined for the intestines), secretorv fibres (for sweat glands), and trophic fibres (for voluntary muscles, for skin, and for joints and bones).