Spinal Canal

His cranial cavity is continuous with the first neck-vertebra; and in that vertebra the bottom of the spinal canal will measure ten inches across, being eight in height, and of a triangular figure with the base downwards. As it passes through the remaining vertebræ the canal tapers in size, but for a considerable distance remains of large capacity. Now, of course, this canal is filled with much the same strangely fibrous substance—the spinal cord—as the brain; and directly communicates with the brain.