Experimental evidence of reciprocal temperature relationship between the parietofrontal region and the orbital emissary vein in the pony

Abstract

The heads of 5 ponies were embalmed and the vessels were double injected with latex. Dissection of these specimens revealed venous pathways (1) from the nasal area to the cavernous sinus and (2) from the parietofrontal region to the ventral petrosal sinus. Thermistors were chronically implanted near the orbital emissary veins of 3 additional ponies. Hot and cold packs were applied alternately to the parietofrontal regions. The temperature near the orbital emissary veins increased during the 5 trials with cold application and decreased during the 5 trials with hot application. The authors were able to influence physiologic adjustments in the heat loss in the nasal area (evidenced by temperature changes near the orbital emissary veins) by imposing nonphysiologic changes in the temperature of the venous blood draining the parietofrontal region.