THE CARDIOVASCULAR CAROTID SINUS REFLEX

Abstract

A study has been made of the anatomy of the carotid sinus region of the dog in order to determine the nerves ending in the carotid sinus. The physiologic function of the nerves supplying the sinus has been investigated and the following results obtained: Anatomically, the carotid sinus possesses 3 sources of nerve supply: a branch from the posterior division of the glossopharyngeal nerve, a branch from the superior cervical ganglion, and a small nerve which accompanies the internal carotid artery. Electric stimulation indicates that the nerve accompanying the internal carotid artery is not concerned in the carotid sinus reflex. A study of the comparative responses of the sympathetic nerve and the sinus nerve to electric stimulation shows the greater importance of the sinus nerve. On the basis of acute and survival denervation expts. it is concluded that the cardiovascular components of the sinus reflex are conducted solely through the sinus nerve. Evulsion of the sinus nerve is submitted as a method of carotid sinus denervation and the surgical approach to the sinus nerve is described. These expts. support the view that the carotid sinus operates entirely through a depressor mechanism.