Definition: Vocal cord paralysis is caused by paralysis of intrinsic muscles of larynx. This is a symptom of an underlying disorder and not a disease by itself. The intrinsic muscles of the vocal cord are supplied by the vagus nerve. The term vagus means "wanderer" which is the apt term to describe this nerve becuase of its long anatomical course.
Unilateral vocal fold paralysis occurs due to dysfunction of recurrent laryngeal or vagus nerve causes a breathy voice. The breathiness of voice is caused by glottic chink which allows air to escape when the patient attempts to speak. Normal voice production is dependent on proper glottal closure resulting from bilateral adduction of the vocal cords. This adduction of vocal folds combined with subglottic air pressure causes the vocal folds to vibrate causing phonation.
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