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AN28.1-10 | Face & parotid region — Gate Quiz
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The five terminal branches of the facial nerve (CN VII) are correctly listed as:
Correct! The five terminal branches of CN VII are: Temporal, Zygomatic, Buccal, Marginal mandibular, and Cervical. Remember "To Zanzibar By Motor Car."
CN VII branches emerge from the parotid plexus (pes anserinus — "goose's foot"). Temporal: forehead + upper orbicularis oculi. Zygomatic: lower orbicularis oculi. Buccal: buccinator + orbicularis oris. Marginal mandibular: depressor anguli oris. Cervical: platysma.
Incorrect. CN VII terminal branches: Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical. Mnemonic: "To Zanzibar By Motor Car." The lingual, frontal, and ophthalmic nerves are branches of CN V (trigeminal), not CN VII.
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A 50-year-old man has right-sided facial weakness. On examination, he cannot close his right eye, cannot smile on the right, but CAN wrinkle the right side of his forehead. This pattern indicates:
Correct! Forehead sparing in a contralateral facial weakness pattern = UMN lesion. The frontalis is bilaterally innervated from the cortex. A left hemispheric stroke → right-sided corticobulbar weakness → right-sided lower face weakness, but right frontalis is maintained by the intact right cortex.
Forehead sparing = UMN (stroke/cerebral). Forehead involved = LMN (Bell's palsy, parotid tumour, pontine lesion). The frontalis muscle is the key discriminator. This distinction is fundamental for differentiating a stroke from Bell's palsy in casualty.
Incorrect. The key is "right facial palsy with forehead SPARING." If the right frontalis is functional, the lower motor neurone (CN VII nucleus → nerve → muscles) is intact. The frontalis receives bilateral cortical input — so it only fails in LMN lesions, not UMN lesions.
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The parotid (Stensen's) duct opens into the oral cavity at which location?
Correct! The parotid duct (Stensen's duct) opens into the vestibule of the oral cavity opposite the crown of the upper 2nd molar tooth. This is a clinically and anatomically significant landmark.
Salivary duct openings: Parotid (Stensen's) → opposite upper 2nd molar; Submandibular (Wharton's) → floor of mouth, sublingual papilla beside tongue frenulum; Sublingual (Bartholin's/multiple ducts) → plica sublingualis on floor of mouth.
Incorrect. Parotid duct → opens opposite the upper 2nd molar. Compare: submandibular duct (Wharton's duct) → opens at the floor of mouth beside the frenulum. Sublingual glands → multiple small ducts opening along the plica sublingualis.
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Which structure lies deepest within the parotid gland (closest to the pharyngeal wall)?
Correct! Within the parotid gland, from deep to superficial: external carotid artery (deepest) → retromandibular vein → facial nerve (CN VII) (most superficial of the major contents). Mnemonic: "Some Rascals May Find Answers" (from deep to superficial).
Parotid contents — depth order: ECA → retromandibular vein → facial nerve. The ECA divides into superficial temporal and maxillary arteries within the gland. The retromandibular vein forms from the superficial temporal and maxillary veins. CN VII is most superficial — surgeons locate it at the stylomastoid foramen before entering the gland.
Incorrect. Deep to superficial in parotid: ECA (deepest) → retromandibular vein → CN VII (most superficial). This determines the approach in parotidectomy — the facial nerve is superficial and must be identified first.
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Following parotidectomy, a patient develops sweating and flushing of the cheek when eating (gustatory sweating). The mechanism is:
Correct! Frey's syndrome is caused by aberrant nerve regeneration. After parotid surgery, parasympathetic secretomotor fibres of the auriculotemporal nerve (which previously innervated the parotid) regenerate into the sympathetic nerves supplying sweat glands and skin vessels of the cheek. Eating → parasympathetic activation → sweat glands activated instead of salivary glands.
Frey's syndrome: auricolotemoporal nerve (CN V3) carries parasympathetic secretomotor fibres from the otic ganglion to the parotid. After parotidectomy, these fibres regenerate aberrantly to innervate sweat glands. Treatment: glycopyrrolate cream (anticholinergic) or botulinum toxin injection into the affected cheek.
Incorrect. Frey's syndrome is a nerve regeneration phenomenon. Parasympathetic fibres (auriculotemporal nerve) misdirect into sympathetic sweat gland nerves → eating triggers facial sweating instead of (or in addition to) salivation.
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A 65-year-old woman has severe electric shock-like pain lasting seconds, triggered by eating and speaking, localised to the cheek and upper lip on the right side. Which division of the trigeminal nerve is most likely affected?
Correct! The cheek and upper lip are supplied by CN V2 (maxillary division), specifically the infraorbital nerve. Trigeminal neuralgia in the V2 territory presents with pain in the cheek, upper lip, and lateral nose. V2 is the most commonly affected division along with V3.
Trigeminal neuralgia territories: V1 → forehead, nose, upper eyelid (uncommon for neuralgia). V2 → cheek, upper lip, lower eyelid (common). V3 → lower lip, chin, mandibular teeth (most common). Pain in V2/V3 triggered by eating, speaking, shaving, cold wind. First-line: carbamazepine.
Incorrect. Cheek + upper lip sensory supply = CN V2 (maxillary division) via infraorbital nerve. V1 supplies forehead and nose bridge; V3 supplies chin and lower lip.
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The pulse of the facial artery can be felt clinically at which location?
Correct! The facial artery winds around the inferior border of the mandible at the anterior border of the masseter muscle. Here it is superficial and palpable — a useful clinical pulse point.
Facial artery: arises from ECA → grooves submandibular gland → hooks over inferior mandible border (anterior to masseter — pulsation palpable here) → runs tortuously upward across face → terminates as angular artery at medial canthus. The tortuous course accommodates mandibular and facial movements.
Incorrect. The facial artery is palpable at the lower border of the mandible at the anterior border of masseter. The pulse anterior to the tragus is the superficial temporal artery, not the facial artery.
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Which lymph node group is the first to receive drainage from the anterior two-thirds of the tongue?
Correct! The tip of the tongue drains to the submental nodes. The rest of the anterior 2/3 drains to the submandibular nodes (and some directly to deep cervical). The posterior 1/3 drains to the upper deep cervical nodes directly.
Tongue lymphatics: Tip → submental (Level I). Anterior 2/3 (body/lateral) → submandibular (Level I). Posterior 1/3 → jugulodigastric/upper deep cervical (Level II). All eventually → deep cervical chain. Oral/tongue cancer staging uses this — neck dissection levels reflect drainage territories.
Incorrect. Anterior 2/3 of tongue: tip → submental nodes; body → submandibular nodes. Posterior 1/3 → upper deep cervical (jugulodigastric) nodes. This is critical in oral cancer staging as submental and submandibular nodes are the first-tier nodes.
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The deep facial vein is surgically important because it:
Correct! The deep facial vein connects the facial vein (anteriorly) to the pterygoid venous plexus (in the infratemporal fossa). The pterygoid plexus communicates with the cavernous sinus via emissary veins. This provides a second route for intracranial infection spread from dental/facial sources.
Deep facial vein: connects facial vein → pterygoid venous plexus → emissary veins → cavernous sinus. Infection from dental abscesses, deep face infection can spread via this route. In surgery of the infratemporal fossa (e.g., coronoid fractures, deep parotid access), the pterygoid plexus is a source of significant haemorrhage.
Incorrect. The deep facial vein's surgical importance lies in its connection between the facial vein and pterygoid plexus → cavernous sinus route. It also poses a haemorrhage risk in surgery of the infratemporal fossa.
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A patient has complete facial palsy on the left with loss of taste on the anterior 2/3 of the left tongue and reduced lacrimation on the left. Stapedial reflex is INTACT. The lesion is most likely located:
Correct! Loss of taste (chorda tympani affected) + reduced lacrimation (greater petrosal nerve affected? — wait: if lacrimation is reduced, greater petrosal must be affected, placing the lesion above geniculate ganglion. However, if stapedial reflex is INTACT, the nerve to stapedius is functional, so the lesion is between the nerve to stapedius and the chorda tympani.
CN VII localisation in facial canal (distal to proximal): Stylomastoid foramen → Chorda tympani exits → Nerve to stapedius exits → Geniculate ganglion (greater petrosal exits). Intact stapedial reflex = lesion below nerve to stapedius. Lost taste = above chorda tympani. Therefore: between these two points.
Incorrect. Localisation: Intact stapedial reflex → nerve to stapedius is working → lesion is below the origin of nerve to stapedius. Loss of taste → chorda tympani is affected → lesion is above the exit of chorda tympani. Therefore lesion = between nerve to stapedius origin and chorda tympani origin.
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