Final answer:
The hypoglossal nerve (cranial nerve XII) passes through the mylohyoid and hyoglossus muscles, playing a key role in the motor function of the tongue.
Step-by-step explanation:
The nerve that passes through the mylohyoid and hyoglossus muscles is the hypoglossal nerve (cranial nerve XII). The hypoglossal nerve is responsible for motor innervation of the muscles of the tongue. The mylohyoid muscle, which raises the floor of the mouth and elevates the tongue, is innervated by a branch of the nerve called the mylohyoid nerve, a branch of the inferior alveolar nerve from the mandibular division of the trigeminal nerve (cranial nerve V). The hyoglossus muscle, originating from the hyoid bone, is directly innervated by the hypoglossal nerve itself, allowing it to retract and depress the tongue.