Which of the following cranial nerves is classified as purely motor?

Explanation

## Classification of Cranial Nerves by Function **Key Point:** Cranial nerves are classified as sensory (I, II, VIII), motor (III, IV, VI, XI, XII), or mixed (V, VII, IX, X). ### Purely Motor Cranial Nerves The **abducens nerve (CN VI)** is a purely motor nerve that innervates the lateral rectus muscle of the eye, responsible for abduction of the eyeball. ### Other Purely Motor Nerves The complete list of purely motor cranial nerves includes: | Nerve | Number | Function | | --- | --- | --- | | Oculomotor | III | Eye movements (superior/medial/inferior recti, inferior oblique, levator palpebrae) | | Trochlear | IV | Superior oblique muscle of eye | | Abducens | VI | Lateral rectus muscle of eye | | Accessory | XI | Sternocleidomastoid, trapezius | | Hypoglossal | XII | Tongue muscles | **High-Yield:** Remember that CN III, IV, VI control eye movements and are all motor. CN XI and XII are spinal/brainstem motor nerves. **Mnemonic:** **"Oh Oh Oh, To Touch And Feel Very Good Vibes And Hear Sounds"** — but for purely motor: **"Some Say Money Matters, But My Brother Says Big Brains Matter"** (CN III, IV, VI, XI, XII are motor). ### Why Abducens is the Answer Abducens is unambiguously motor-only: it has no sensory component and innervates only the lateral rectus muscle.