NBEO Ocular Anatomy Posterior Segment (Post Seg) and Cranial Nerves Practice Test

The stapedius muscle is innervated by a branch of the facial nerve, specifically the nerve to stapedius, which travels through the middle ear to motorly innervate the stapedius. This small muscle helps dampen vibrations of the stapes to protect the inner ear from loud sounds, a key part of the acoustic reflex. The other nerves listed do not supply stapedius: the tensor tympani is innervated by the mandibular division of the trigeminal nerve (CN V), while CN IX and CN X innervate other pharyngeal and laryngeal muscles and structures. Therefore, cranial nerve VII is the correct innervation.