| Muscles Innervated by Cranial Nerves |
| Cranial Nerve | Muscle | Lesion |
| Oculomotor nerve (CN III) | Extraocular muscles innervated by CN III aresuperior rectus (SR)infecrior rectus (IR)medial rectus (MR)inferior oblique (IO)Levator palpebrae
superiorisCiliary muscleSphincter pupillae | DiplopiaPtosisLoss of accomodationDilated pupil and loss of light reflex |
| Trochlear nerve (CN IV) | Superior oblique | Difficulty looking downHead tilt away from the side of the lesion |
| Mandibular branch of the trigeminal nerve (CN V3) | Muscles of mastication which includeMandibular elevatorsmasseter muscletemporalis musclemedial pterygoid muscle Mandibular depressorslateral pterygoid muscle anterior belly of the diagstric musclemylohyoid muscleTensor palatiTesnor tympani | Jaw deviation towards the side of the lesion |
| Abducens nerve (CN VI) | Lateral rectus | Horizontal diplopia |
| Facial nerve (CN VII) | Muscles of facial expressionPosterior belly of digastric muscleStylohyoid muscleStapedius muscle | Bell’s palsyLoss of blink reflexHyperacusis (when the stapedius is involved) |
| Glossopharyngeal nerve (CN IX) | Stylopharyngeus muscle | – |
| Vagus nerve (CN X) | Muscles of the palate and pharynx excepttensor palati muscle (CN V3)Stylopharyngeus muscle (CN IX)All muscles of the larynx | Palate droopDysphagiaDeviation of the uvula away from the side of the lesionLoss of gag reflex (the sensory component of this reflex is mostly via CN IX) |
| Accessory nerve (CN XI) | Sternocleidomastoid muscleTrapezius muscle | Weakness with turning of the headShoulder droop |
| Hypoglossal nerve (CN XII) | Muscles of the tongue except for thepalatoglossus muscles | Tongue deviation towards the side of the lesion |
