Blood supply to the nasal cavity of sheep (Ovis aries) and its significance to brain temperature regulation.

Blood supply to the nasal cavity of the sheep has been grossly studied on 25 specimens by employing different injection techniques. Following intramuscular injection of Rompun solution (Xylazine hydrochloride, 10 mg/lb body weight), the animals were killed either by bleeding or decapitation. Subsequently, the heads were perfused with physiologic saline solution, injected with various intravascular materials, and then either routinely dissected or macerated to trace the vessels. The nasal cavity of the sheep was mainly supplied by the sphenopalatine and ethmoidal, and indirectly by their anastomoses with the infraorbital, malar, major palatine, and the superior labial arteries. The venous drainage of the nasal cavity has connections with the cavernous sinus via: 1. the dorsal and/or the lateral nasal veins-angularis oculi vein-ophthalmic plexus; and 2. via the sphenopalatine vein-rostral branch of the deep facial-pterygoid plexus. The former venous pathway has also been confirmed by venography in one live anesthetized sheep. The internal carotid rete was found to be enmeshed in a venous plexus of the cavernous sinus. From their close relationship it may be inferred that their function is to accommodate flow in opposite directions and that such an arrangement has the necessary anatomic requirements expected of a countercurrent heat exchanger.