This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
In the spinal cord we have to distinguish three functions : that of conduction, that of reflex action, and that of origination of nerve-force, as in the sweat-centres, etc, contained in it.
The spinal cord transmits sensory or afferent impulses upwards to the medulla and brain; and motor impulses downwards to the muscles, as well as other efferent impulses to the glands. It transmits reflex impulses across, either from behind forwards, or laterally from one half of the cord to the other. Transmission from behind forwards occurs when the impulse passes from the sensory to the motor columns on the same side, as in the case of reaction of a sensory stimulus on the same side of the body. It occurs laterally when the sensory stimulus produces motion, not on the same side, but on the opposite side of the body.