Which of the following muscles is innervated by the mandibular division of the trigeminal nerve?

Explanation

## Motor Innervation of the Mandibular Division (V3) **Key Point:** The mandibular division (V3) is the ONLY division of the trigeminal nerve that carries motor fibers. It innervates the muscles of mastication and related structures. ## Muscles of Mastication Innervated by V3 | Muscle | Action | Innervation | | --- | --- | --- | | **Medial pterygoid** | Elevation, protrusion of mandible | Mandibular division (V3) | | Lateral pterygoid (superior head) | Elevation of mandible | Mandibular division (V3) | | Lateral pterygoid (inferior head) | Depression, protrusion of mandible | Mandibular division (V3) | | Masseter | Elevation of mandible | Mandibular division (V3) | | Temporalis | Elevation, retraction of mandible | Mandibular division (V3) | | Mylohyoid | Elevation of floor of mouth | Mandibular division (V3) | | Anterior belly of digastric | Elevation of floor of mouth | Mandibular division (V3) | | Tensor veli palatini | Tenses soft palate | Mandibular division (V3) | | Tensor tympani | Tenses tympanum | Mandibular division (V3) | **High-Yield:** Medial pterygoid is a frequently tested muscle because it is a muscle of mastication and is exclusively innervated by V3. Bilateral medial pterygoid contraction elevates and protrudes the mandible. **Mnemonic:** "**MMATT**" — Muscles of mastication innervated by V3: - **M**asseter - **M**edial pterygoid - **A**nterior belly of digastric - **T**emporalis - **T**ensor veli palatini & Tensor tympani **Clinical Pearl:** Damage to V3 (e.g., from skull base fracture or surgical injury) results in weakness of jaw closure and deviation of the mandible toward the affected side (due to unopposed action of the contralateral lateral pterygoid).