Superior laryngeal nerve
The external branch functions to stretch the vocal cords by activating the cricothyroid muscle, increasing pitch.A filament descends beneath the mucous membrane on the inner surface of the thyroid cartilage and joins the recurrent laryngeal nerve.[2] A superior laryngeal nerve palsy changes the pitch of the voice and causes an inability to make explosive sounds due to paralysis of the cricothyroid muscle.[5][6] The external branch is susceptible to damage during thyroidectomy or cricothyrotomy, as it lies immediately deep to the superior thyroid artery.The lesion of this branch (for example, during surgery) that seeks an anterior approach to the cervix, is associated with a loss of the laryngeal reflex of cough and an elevated risk of aspiration pneumonia.