Which nerve provides motor innervation to the cricothyroid muscle?

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The cricothyroid muscle is uniquely innervated by the external branch of the superior laryngeal nerve, a branch of the vagus nerve (CN X). This specific branch travels to the larynx and provides motor fibers to cricothyroid, whose action is to tense and elongate the vocal cords by tilting the thyroid cartilage forward at the cricothyroid joint, raising pitch. In contrast, most other intrinsic laryngeal muscles are supplied by the recurrent laryngeal nerve, also a branch of CN X, which carries motor innervation to muscles like the thyroarytenoid, interarytenoids, and the cricoarytenoid group. The vagus nerve gives rise to both of these laryngeal branches, while the hypoglossal nerve controls tongue muscles rather than the larynx. So, motor innervation to cricothyroid specifically comes from the external branch of the superior laryngeal nerve.