Location of median and ulnar motornuclei in the cat.

In the cat we used the horseradish peroxidase (HRP) technique to investigate the location of the motor nuclei projecting through the median and the ulnar nerves. Each nucleus is described b its longitudinal extent along the rostro-caudal spinal cord axis and by its dorso-ventral and medio-lateral position within the ventral horn. The topographical relations between different nuclei are, however, only provisionally ascertained with the HRP technique, since the simultaneous use of different fluorescent tracers in the same animal is a more powerful approach to establish the spatial relations between different neuronal populations. One example with the latter technique is reported, which demonstrates the complete overlap of two different nuclei.