Which branch of CN V carries parasympathetic fibers to the submandibular gland?

• A. Auriculotemporal
• B. Lingual nerve
• C. Inferior alveolar
• D. Mental nerve

Answer: (B)

The key idea is how parasympathetic signals reach the submandibular gland. Preganglionic fibers originate in the facial nerve system and travel with chorda tympani. These fibers join the lingual nerve, pass to the submandibular ganglion where they synapse, and then postganglionic fibers hitchhike along the lingual nerve to reach the submandibular (and sublingual) glands to stimulate saliva.

That makes the lingual nerve the correct route for parasympathetic innervation of the submandibular gland. The auriculotemporal nerve, by contrast, carries parasympathetic fibers to the parotid gland via a different pathway (via the glossopharyngeal system and otic ganglion). The inferior alveolar and mental nerves are primarily involved in sensory/motor innervation of the mandible and teeth and do not convey parasympathetic fibers to the submandibular gland.