The superior laryngeal nerve is a branch of the vagus nerve. It arises from the middle of the ganglion nodosum and in its course receives a branch from the superior cervical ganglion of the sympathetic. It descends, by the side of the pharynx, behind the internal carotid artery, and divides into two branches: external laryngeal nerve internal laryngeal nerve A superior laryngeal nerve palsy changes the pitch of the voice and causes an inability to make explosive sounds. If no recovery is evident three months after the palsy initially presents, the damage is most likely to be permanent. A bilateral palsy presents as a tiring and hoarse voice. [ http://en.wikipedia.org/wiki/Superior_laryngeal_nerve ]