The Autonomic Facial Nerve Pathway in Birds: A Tracing Study in Chickens

Abstract
Purpose. In birds, the parasympathetic innervation of the choroid is via the ciliary (cranial nerve III) and pterygopalatine (cranial nerve VII) ganglia, the latter consisting of a chain of microganglia within the orbit. Because of the scattered nature of these microganglia, lesions of this nerve pathway in birds have not been attempted, making interpretation of the functional contribution of this parasympathetic input to the avian eye uncertain. The purpose of this study was to find an extraorbital approach to the preganglionic part of cranial nerve VII and to reveal its peripheral terminals and its site of origin in the brain stem.