Causes of recurrent laryngeal nerve (RLN) injury during thyroidectomy are varied, with most injuries resulting from the following surgical errors: sectioning of the nerve, ligation, traction, clamping injury, suction, compression, contusion, electrical and thermal injury. Surgeons underestimate the actual rate of RLN injury. Intraoperative nerve monitoring (IONM) during thyroidectomy, parathyroidectomy, or related central neck procedures can elucidate actual or potential mechanisms of RLN injury that were previously unknown to the thyroid surgeon, especially in visually intact nerves. IONM is useful in open conventional thyroid surgery for localizing the point of disrupted nerve conduction in addition to identifying how and when the RLN was injured. Studying the mechanisms of RLN injury during thyroidectomy is instructive for future operations and may allow for identification of potentially reversible causes of RLN injury. During thyroidectomy and parathyroidectomy, intraoperative RLN injury is typically associated with a visually intact RLN rather than a transected nerve. The anterior motor branch of a RLN bifurcating near the ligament of Berry is particularly at risk of traction injury. Traction injury is the most frequent cause of postoperative vocal cord palsy.