## Mandibular Division of Trigeminal Nerve (CN V3) ### Sensory Distribution Error **Key Point:** The mandibular division (V3) provides sensory innervation to the **posterior one-third of the tongue** via the lingual nerve, NOT the anterior two-thirds. The anterior two-thirds of the tongue receives sensory innervation from the **chorda tympani** (a branch of CN VII, the facial nerve). **High-Yield:** This is a classic anatomy trap question. Students often confuse the sensory territories of CN V3 and CN VII on the tongue. Remember: **V3 = posterior 1/3, CN VII = anterior 2/3**. ### Correct Statements Verified | Feature | Details | |---------|----------| | **Exit Point** | Foramen ovale (correct) | | **Tongue Sensation** | **Posterior 1/3 only** — anterior 2/3 is CN VII (chorda tympani) | | **Parasympathetic to Submandibular** | Correct — preganglionic fibers via chorda tympani (CN VII) synapse in submandibular ganglion; postganglionic fibers hitchhike on CN V3 lingual nerve | | **Tensor Tympani** | Correct — CN V3 innervates this muscle (aids in dampening loud sounds) | ### Tongue Innervation Mnemonic **Mnemonic: "Seven Anterior, Five Posterior"** - **CN VII (Facial)** → anterior 2/3 of tongue (taste + general sensation via chorda tympani) - **CN V3 (Trigeminal)** → posterior 1/3 of tongue (general sensation via lingual nerve) - **CN IX (Glossopharyngeal)** → posterior 1/3 of tongue (taste via lingual branch) ### Motor and Parasympathetic Components of V3 **Clinical Pearl:** Although CN V3 is primarily sensory, it carries: 1. **Motor fibers** to muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini, and tensor tympani 2. **Parasympathetic fibers** (hitchhiking from CN VII) that ultimately innervate the submandibular and sublingual salivary glands via the submandibular ganglion
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.