Final answer:
The superior laryngeal nerve from cranial nerve X innervates the mucosa above the vocal cords and the cricothyroid muscle, which aids in voice modulation.
Step-by-step explanation:
The superior laryngeal nerve, which branches from the vagus nerve (cranial nerve X), innervates several structures in the neck. It has two main branches: the internal and external laryngeal nerves. The internal laryngeal nerve provides sensory innervation to the mucosa above the vocal cords, while the external laryngeal nerve supplies motor innervation to the cricothyroid muscle. This muscle tensions and elongates the vocal cords, playing a crucial role in phonation and the modulation of pitch. In contrast, the remainder of the intrinsic muscles of the larynx are innervated by the recurrent laryngeal nerve, also a branch of the vagus nerve.