In spite of extensive experimentation with animals on the carotid sinus during the past decade, little is known of the function of this mechanism in man. The following cases are reported because they presented an opportunity to study the alterations in arterial tension which result in human beings when one carotid sinus is denervated.
It is not my purpose here to review the entire literature on the subject of the carotid sinus.1 A brief statement of the known anatomic and physiologic facts will suffice. The carotid sinus is a small bulbous enlargement of the internal carotid artery at its point of origin from the common carotid artery. It receives (in the dog) a nerve from the superior cervical sympathetic ganglion, which is always present, and a small variable nerve which may arise from the vagus (Hering2). Some investigators have described a small branch from the hypoglossal nerve to