 While the sensory input described above is (general) visceral sensation (diffuse, poorly localized), the vocal fold also receives general somatic sensory innervation (proprioceptive and touch) by the superior laryngeal nerve.Injury to the external laryngeal nerve causes weakened phonation because the vocal folds cannot be tightened.Injury to one of the recurrent laryngeal nerves produces hoarseness, if both are damaged the voice may or may not be preserved, but breathing becomes difficult.