THE MACROSCOPIC VASCULAR ANATOMY OF THE EQUINE ETHMOIDAL AREA

The vascular anatomy of the ethmoidal area in six normal horses and tw o normal ponies was studied using vascular-corrosion casts. The major arterial supply to the ethmoidal area stems from an intracranial sourc e. The internal and external ethmoidal arteries anastomose on the rost ral intracranial surface of the cribriform plate to form the arterial ethmoidal rete which arborizes and passes through the perforations of the cribriform plate to supply the ethmoid labyrinth. A minor arterial supply to the ventral portion of the ethmoid labyrinth stems from a s mall caudal nasal branch of the sphenopalatine artery. Multiple parall el venules drain the ethmoid labyrinth rostrally to its apex then join the venous drainage from the surrounding sinuses.