Role of the Sympathetic in Lacrimal Secretion

THI lacrimal gland is innervated by the lacrimal, the facial, and the cervical sympathetic nerves; the anatomical and functional characteristics of each were briefly summarized in a previous communication (Whitwell, 1958). Overwhelming evidence points to the fact that the lacrimal nerve is not secretory in function, but is purely the afferent path of a reflex arc. Similarly, the facial nerve is of prime importance in the control of lacrimation, especially the reflex tear secretion. Nevertheless, in clinical cases of com- plete paralysis of the facial or greater superficial petrosal nerves, although weeping is abolished, the eye remains comfortably moist (Rowbotham, 1939). The problem of the residual secretion remains undecided. It is possible that the completely denervated gland autonomously secretes a constant small amount of tears, or that a blood hormone is the stimulating factor. It is equally possible that the sympathetic nervous system is responsible.