Branch of glossopharyngeal nerve to carotid sinus

The branch of glossopharyngeal nerve to the carotid sinus (Hering's nerve) is a small nerve in the neck, that innervates the carotid sinus and the carotid body. It is a branch of the glossopharyngeal nerve that runs downwards, anterior to the internal carotid artery. It communicates with the vagus nerve and sympathetic trunk and then divides in the angle of the bifurcation of the common carotid artery to innervate the carotid body and carotid sinus. It carries impulses from the baroreceptors in the carotid sinus to the vasomotor center in the brainstem (to help maintain a more consistent blood pressure) and from chemoreceptors in the carotid body (mainly monitoring blood gas PaO2 and PaCO2 levels). Hering's nerve responds to both increases and decreases in blood pressure while the baroreceptors in the aortic arch respond only to increases in blood pressure.