Motor Cell Columns in Rat Lumbar Spinal Cord

The distribution pattern of motoneurons in the rat's lumbar spinal cord which send axons to the sciatic nerve was studied by means of staining degenerated motor cells with toluidine blue after relevant roots or nerves had been sectioned or crushed. The columnar arrangement of the motor cells in the lumbar spinal cord of the normal rats was confirmed and presented. The degeneration picture of the rat motoneuron was presented, which was observed only in the large cells in the ventral horn and not in the smaller cells suggestive of γ-motoneurons. It was found that the sciatic motoneurons occupy the dorsolateral portion of the ventral horn and extend in proximocaudal direction from the mid L4 through L5 to the end of L6. It was proved that the tibial motoneurons innervating the extensors of lower hind-limb and foot are situated dorsolaterally in the sciatic portion of the columnar arrangement of the motor cells, while the peroneal motoneurons innervating the flexors of lower hind-limb occupy the medial section in the sciatic portion.