Functional analysis of the vasomotor innervation of the dog's hind footpad.

Vascular responses in the large central pad of the dog's foot were recorded during stimulation of the lumbosacral sympathetic trunk and correlated with the site of stimulation and the subsequent histologic analysis of the excised trunk. The resulting description of the preganglionic inflow and postgaiiglionic outflow from the trunk demonstrated marked variations in the anatomic patterns of the vasomotor innervation of the footpad in various animals. Complete preganglionic denervation of this vascular bed required extirpation of the entire lumbar trunk caudalward as far as L-7 in addition to the interruption of those preganglionic pathways through the spinal nerves which do not pass through the sympathetic trunk.