Carotid sinus

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Major arteries of the head and neck.

The carotid sinus is a neurovascular structure which presents as a dilation at the bifurcation of the common carotid artery and proximal aspect of the internal carotid artery. It contains numerous stretch receptors, also known as baroreceptors which are sensitive to changes in arterial blood pressure. Therefore, the carotid sinus plays a direct role in the control of blood pressure and heart rate.

There are two types of baroreceptors located in the carotid sinus: type 1 and type 2. Both of which are high-pressure arterial baroreceptors. Receptors which are sensitive to low blood pressure are located within atria, ventricles, and pulmonary vasculature.

On detecting changes in blood pressure, afferent signals are transported from the carotid sinus to the cardiovascular control center in the midbrain by the carotid sinus nerve and subsequent glossopharyngeal nerve (CN IX). In response, efferent signals are emitted via parasympathetic and sympathetic nerves to the heart and blood vessels resulting in decreased cardiac output. This cardiovascular change stimulated in response to the baroreceptors of the carotid sinus is known as carotid sinus baroreflex.