Persistent lower lip lesion

Correct answer: D. Excisional biopsy

• A. Exfoliative cytology samples only surface cells. It cannot assess the architecture of a submucosal nodule, and a negative result would not be reliable. It is an adjunct, never definitive.
• B. Incisional biopsy is reserved for LARGE lesions over about 1 cm, diffuse or multifocal lesions, or lesions where malignancy is suspected and excision would be disfiguring or would compromise definitive surgical planning. A small discrete lip nodule does not fit.
• C. Fine-needle aspiration is valuable for deep masses and lymph nodes, particularly major salivary gland lesions, but for a small accessible mucosal nodule it gives less information than simply removing it.
• D. CORRECT. The governing rule is SIZE and accessibility, not duration. A lesion under about 1 cm that is well-defined and surgically accessible is removed entirely with a margin of normal tissue — an EXCISIONAL biopsy. This gives the pathologist the whole lesion with its architecture intact, and it is simultaneously diagnostic and therapeutic, sparing the patient a second procedure.

Note: The commonest lower lip nodule of this description is a mucocele or a fibroma, both of which are managed by excision anyway.

Correct answer: A. The mental nerve

• A. CORRECT. The MENTAL NERVE is the terminal branch of the inferior alveolar nerve, emerging from the mental foramen between the mandibular premolar apices. It divides into labial branches supplying the mucosa and skin of the lower lip and the chin. This is why a mental block anaesthetises the lower lip, and why lower lip numbness after surgery or trauma localises to the mental foramen region.
• B. The lingual nerve supplies the anterior two-thirds of the tongue, the floor of mouth and the lingual gingiva.
• C. The long buccal nerve supplies the buccal mucosa and buccal gingiva of the mandibular molars — the cheek, not the lip.
• D. The marginal mandibular branch of the facial nerve is MOTOR to the lower lip muscles. Injuring it paralyses the lip but leaves sensation intact — the distinction this case is built around.

Note: Both nerves are V3-related in a sense but they are entirely different systems: sensory lip = mental nerve from V3; motor lip = facial nerve, CN VII.

Correct answer: D. The parotid gland

• A. The infratemporal fossa contains V3, the maxillary artery, the pterygoid muscles and the pterygoid venous plexus. The facial nerve does not traverse it.
• B. The submandibular gland lies below the mandible near the marginal mandibular branch, which is why the nerve is at risk during submandibular surgery, but the nerve passes SUPERFICIAL to the gland rather than through it.
• C. The pterygomaxillary fissure transmits the maxillary artery and the maxillary division of the trigeminal nerve into the pterygopalatine fossa. It is a V2 route, not a facial nerve one.
• D. CORRECT. Motor supply to the lower lip comes from the MARGINAL MANDIBULAR branch of the facial nerve. The facial nerve exits the skull at the stylomastoid foramen, enters the PAROTID GLAND, and divides within it into its five terminal branches — temporal, zygomatic, buccal, marginal mandibular and cervical. The marginal mandibular branch then runs forward, often below the inferior border of the mandible, to reach depressor anguli oris, depressor labii inferioris and mentalis.

Note: Surgical relevance: the marginal mandibular branch is the most frequently injured facial nerve branch in submandibular and neck procedures. Injury produces an asymmetric smile with the lower lip failing to depress — without any loss of sensation.

Correct answer: A. Recurrent laryngeal nerve

• A. CORRECT. The RECURRENT LARYNGEAL NERVE, a branch of the vagus, supplies all the intrinsic laryngeal muscles except cricothyroid. Damage paralyses the vocal cord on that side, producing HOARSENESS. Its long, vulnerable course explains the clinical pattern: the left nerve loops under the aortic arch, so left-sided hoarseness may signal an aortic aneurysm, a mediastinal mass, or lung cancer, while both nerves are at risk in thyroid surgery.
• B. The hypoglossal nerve is motor to the tongue. Injury causes deviation of the protruded tongue TOWARD the damaged side, with wasting and fasciculation — speech is slurred, not hoarse.
• C. The EXTERNAL branch of the superior laryngeal nerve supplies cricothyroid, the vocal cord tensor. Injury weakens the high register and causes voice FATIGUE rather than frank hoarseness — a career-ending injury for a singer but a subtler finding.
• D. The glossopharyngeal nerve supplies sensation and taste to the posterior third of the tongue, the oropharynx, and motor supply to stylopharyngeus. Injury causes swallowing difficulty and loss of the gag reflex, not hoarseness.

Note: Persistent unexplained hoarseness lasting more than two to three weeks warrants ENT referral. It is a recognised warning sign for laryngeal and lung malignancy.