Origin of lumbar cerebrospinal fluid pulse wave.

System analysis was performed on 16 adult mongrel dogs to determine the origin of the lumbar cerebrospinal fluid pulse wave. The descending thoracic aorta was occluded to evaluate the effects of the spinal arterial pulsations, and the thoracic aorta and inferior vena cava were simultaneously occluded to evaluate the effects of the spinal venous pulsations. It was concluded that, in the first harmonic wave, the components of the lumbar cerebrospinal fluid pulse wave are as follows: spinal arterial pulsations, 39.4%; spinal vascular (arteries and veins) pulsations, 77%; venous pulsations in the spinal canal, 37.6%; and the intracranial pressure pulse wave transmitted through the spinal canal from the intracranial space to the lumbar level, 23%.