Abstract
We investigated the distribution of motoneurons corresponding to cervical nerve roots using the HRP (horseradish peroxidase) method and investigated the anatomical levels of anterior and posterior filaments and discs. Forty forelimbs of Wistar rats were used.
We injected 250I. U. HRP solution into the roots and the levels of anterior and posterior filaments and discs were marked under a microscope. HRP labeled motoneurons were counted on each level, and compared with the levels of anterior and posterior filaments and discs.
Motoneurons corresponding to the C5 nerve root were distributed from the middle of the C4 segment to the middle of the C6 segment. C6 nerve roots were from the middle of C5 to the middle of C7. C7 nerve roots were from the lower part of C6 to the middle of C8. C8 nerve roots were from the lower part of C7 to the middle of Th1. Th1 nerve roots were from the lower part of C8 to the upper part of Th2.
The Labeled motoneurons were almost all located in each segment from the C5 to Th1 nerve root. The percentages were 94.7%, 95.7%, 95.9%, 92.9%, 94.0%. Anterior and posterior filament levels were almost all the same from C5 to Th1. Spinal segments were one segment higher than disc levels.
