[Ponto-medullary projections to the spinal cord: a quantitative study in the cat]

The purpose of this research has been to study quantitatively the ponto-medullary projections to the lateral and ventral funiculi in both cervical (C3) and thoracic (Th8) levels. The method consisted in the partial interruption of the spinal cord, sparing one funiculus in which 5-30 microliter of HRP 30% solution was injected at about 1 cm caudally. 19 cats were utilized, 12 for cervical (6 for lateral and 6 for ventral funiculus) and 7 for lumbar injection (3 for lateral and 4 for ventral funiculus). The structures which project to both funiculi of spinal cord (RM, RL, Poo, PR at Th8 level; RM, RL, Poo at C3 level) could exert integrative effects on the proximal and distal segments of the limbs. The structures which project only to FV (VL and Poc at Th8 level; VL, VIN and Poc at C3 level) or to FL (LSC at Th8; PR at C3) could be implied in motor control of only the proximal or distal regions.