Branch of glossopharyngeal nerve to carotid sinus 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
Carotid body acid-base transporters (e.g. Na-H) which raise intracellular pH, and activates transporters (e.g. Cl-HCO) which decrease it. Changes in proton concentration caused by acidosis (or the opposite from alkalosis) inside the cell stimulates the same pathways involved in P sensing. Another mechanism is through oxygen sensitive potassium channels. A drop in dissolved oxygen lead to closing of these channels which results in depolarization. This leads to release of the neurotransmitter dopamine in the glossopharyngeal and vagus afferente to the vasomotor area. The type I (glomus) cells in the carotid (and aortic bodies) are derived from neuroectoderm and are thus electrically excitable.