Vocal cords, also known as vocal folds, are two muscular bands located inside the larynx or voice box that allow humans to produce sounds through vocalization. They are composed of twin infoldings of mucous membrane stretched horizontally, from back to front, across the larynx. When you breathe in and out, your vocal cords open so air can flow freely. When you speak, your vocal cords close by meeting in the middle of your exhaled airstream and vibrate, creating the sound of your voice. The size of the vocal cords affects the pitch of the voice. The vocal cords are controlled via the recurrent laryngeal branch of the vagus nerve. The lower vocal folds are lined with a thick stratified squamous epithelium, which functions to protect the mucosa from abrasion caused by the rapid movement of air when breathing and during phonation.