A 72-year-old woman with a 40-year smoking history presents with progressive dyspnea, hoarseness, and dysphagia over 2 months. She has unintentional weight loss of 4 kg. Laryngoscopy shows a left vocal cord fixed in a paramedian position with a visible mass at the left vocal cord margin. CT chest reveals a 3 cm left lung apex mass with invasion of the left recurrent laryngeal nerve. Which nerve lesion accounts for the vocal cord position in this patient?