Three tongues and a salivary gland

Correct answer: C. The chorda tympani branch of the facial nerve

• A. The LINGUAL NERVE is the CARRIER of these fibres for the final part of their course, but they are not its own. The lingual nerve's own function is general sensation — touch, temperature and pain — from the anterior two-thirds of the tongue.
• B. The hypoglossal nerve is purely MOTOR to the intrinsic and most extrinsic tongue muscles. It carries no secretomotor, sensory or gustatory fibres.
• C. CORRECT. Secretomotor fibres to the SUBMANDIBULAR and SUBLINGUAL glands arise in the superior salivatory nucleus and travel in the CHORDA TYMPANI, a branch of the FACIAL NERVE (CN VII). The chorda tympani joins the LINGUAL NERVE in the infratemporal fossa, and the fibres synapse in the SUBMANDIBULAR GANGLION, which is suspended from the lingual nerve, before reaching the glands. So the answer to ‘which nerve innervates the submandibular gland’ is the facial nerve, delivered by way of the lingual.
• D. That describes the PAROTID pathway, which is the classic point of confusion. CN IX supplies the parotid by way of the lesser petrosal nerve and the OTIC ganglion, with the auriculotemporal nerve as the final carrier.

Note: The chorda tympani carries TASTE from the anterior two-thirds of the tongue as well as these secretomotor fibres. That dual cargo explains why a LINGUAL NERVE injury during third molar surgery can cost the patient both sensation and taste on that side — and, in principle, salivary secretion too. Keep the two salivary pathways paired in memory: CN VII → chorda tympani → submandibular ganglion → submandibular and sublingual; CN IX → lesser petrosal → otic ganglion → parotid.

Correct answer: D. Fissured tongue — reassurance and instruction to brush the dorsum

• A. Oral hairy leukoplakia is a corrugated white patch on the LATERAL border of the tongue that does not rub off, driven by Epstein-Barr virus in an immunosuppressed patient. It is a surface plaque, not a fissure pattern.
• B. Atrophic glossitis is a smooth, red, DEPAPILLATED tongue caused by iron, folate or vitamin B12 deficiency — a LOSS of papillae, the opposite finding to deep grooves in a normally papillated dorsum.
• C. Median rhomboid glossitis is a well-demarcated DEPAPILLATED rhomboid patch in the MIDLINE of the posterior dorsum, associated with candidal infection. It is a smooth area, not a set of grooves.
• D. CORRECT. FISSURED TONGUE — also called scrotal or plicated tongue — is a benign developmental variant affecting roughly 5% of the population, with prevalence rising with age. It requires NO treatment. The only useful advice is to BRUSH THE DORSUM of the tongue, because food debris and micro-organisms accumulate in the grooves and can cause halitosis or a localised inflammation. Its associations are worth knowing: GEOGRAPHIC TONGUE, DOWN SYNDROME, and MELKERSSON-ROSENTHAL syndrome — the triad of fissured tongue, recurrent facial paralysis and orofacial oedema.

Note: The reassurance itself is the treatment, and it should be explicit: this is a normal anatomical variant, it is not a sign of infection, deficiency or cancer, and it will not change. Patients frequently arrive having found alarming material online, so naming it plainly matters.

Correct answer: D. Geographic tongue (benign migratory glossitis)

• A. Lichen planus produces bilateral lacy WICKHAM STRIAE, most characteristically on the buccal mucosa, and its lesions persist in place rather than migrating.
• B. Squamous cell carcinoma is a persistent, INDURATED, progressively enlarging lesion of the lateral border. A lesion that MOVES is not a carcinoma, and that is the single most reassuring discriminator available at the chairside.
• C. Erythematous candidiasis gives a diffuse red and often painful tongue, classically following antibiotic or inhaled steroid use or beneath a denture, and it responds to antifungal therapy. It has no raised serpiginous white border and does not move.
• D. CORRECT. BENIGN MIGRATORY GLOSSITIS, also called erythema migrans or geographic tongue. The defining feature is exactly what this patient describes — MIGRATION. Lesions heal in one area and appear in another over days to weeks, which no neoplastic or infective process does. The appearance is of well-demarcated depapillated red patches with raised white serpiginous margins. Histologically it resembles psoriasis, and it is associated with PSORIASIS and with FISSURED TONGUE, both relevant here. It is entirely benign.

Note: Management is reassurance. A minority of patients report sensitivity to acidic, spicy or salty food, which is managed by avoidance and occasionally a topical corticosteroid or topical anaesthetic rinse. Documenting the lesion photographically at one visit and comparing at the next is a simple and convincing way to demonstrate migration to an anxious patient.