HNSS Anatomy — Highest-Yield One-Pager

Lesion directions

• Tongue → TOWARD CN XII lesion (healthy genioglossus pushes)
• Uvula → AWAY from CN X lesion (healthy levator veli palatini pulls)
• Jaw → TOWARD CN V3 lesion (healthy lateral pterygoid pushes)
• CN XI: shoulder droop, weak shrug, weak turn to opposite side
• Torticollis: head tilts to affected SCM, chin to opposite side

Reflexes (afferent → efferent)

• Light: II → III (parasympathetic, ciliary ganglion → sphincter pupillae)
• Corneal: V1 (nasociliary) → VII (bilateral blink)
• Gag: IX → X · Cough: internal laryngeal (X) afferent
• Carotid sinus (baro) + carotid body (chemo) = IX

CN VII branch order — “Tears, Ears, Taste, Face”

• Greater petrosal → pterygopalatine ggl → lacrimal + nose/palate glands
• Nerve to stapedius → hyperacusis if lost
• Chorda tympani → lingual n. → submandibular ggl → submandibular + sublingual; taste ant ⅔ (never the lacrimal gland)
• Stylomastoid foramen → face only. A single-branch lesion loses only that branch.
• Lesser petrosal (IX) → otic ggl → auriculotemporal → parotid

Neck

• Carotid sheath: CCA medial · IJV lateral · X posterior; ansa anterior; sympathetic trunk posterior. Deep cervical nodes on IJV; superficial on EJV.
• CCA bifurcates at superior border of thyroid cartilage
• Anterior scalene: phrenic (C3–5) + subclavian vein anterior; subclavian artery + plexus trunks posterior (interscalene △)
• Subclavian “VIT C D”: vertebral, internal thoracic, thyrocervical (inf. thyroid, transverse cervical, suprascapular) · costocervical · dorsal scapular
• ECA “SALFOPMS”: sup. thyroid, asc. pharyngeal, lingual, facial, occipital, post. auricular, maxillary, superficial temporal
• Triangles: carotid = post. digastric + sup. omohyoid + SCM; submandibular = mandible + 2 digastric bellies; posterior = SCM + trapezius + clavicle (CN XI, Erb’s point)
• Danger space (alar ↔ prevertebral) → diaphragm; retropharyngeal → T1–T2
• Diaphragm pain → shoulder (phrenic + supraclavicular = C3–5)
• Horner “PAM”: ptosis (superior tarsal), anhidrosis, miosis — Pancoast, neck trauma, thyroid/carotid surgery

Larynx

• PCA = only abductor (“Pulls Cords Apart”) — RLN. Bilateral RLN → stridor.
• Cricothyroid tenses → ↑ pitch (external laryngeal); thyroarytenoid relaxes → ↓ pitch
• Vocal fold = dividing line: above = internal laryngeal, sup. laryngeal a., superior deep cervical nodes · below = RLN, inf. laryngeal a., inferior deep cervical + pre/paratracheal. Vocal folds: sparse lymph → rare mets.
• Vestibular (false) fold = quadrangular membrane · vocal (true) = conus elasticus · ventricle between
• RLN loops: R subclavian a. / L aortic arch
• Cricothyroidotomy = cricothyroid ligament · tracheostomy = between rings
• Epiglottis = elastic cartilage; seals the laryngeal inlet

Pharynx & swallowing

• Nasopharynx lateral wall: tube opening → torus tubarius → pharyngeal recess (NPC hides here)
• Pharyngotympanic tube = MIDDLE ear ↔ nasopharynx; opened by TVP (V3), LVP + salpingopharyngeus (X). Kids: short, horizontal → otitis media.
• Vallecula = oropharynx, laryngoscope blade · piriform recess = laryngopharynx, fish bone → internal laryngeal n.
• Longitudinal: stylo (IX, widens), palato (shortens), salpingo — all elevate
• Killian’s triangle (thyropharyngeus/cricopharyngeus) → Zenker’s
• Retropharyngeal space: sympathetic trunk + CN IX–XII near the skull base; NPC compresses them

Tonsil / oropharynx

• Anterior pillar = palatoglossal fold · posterior = palatopharyngeal · tonsil between
• Oropharyngeal isthmus = between the palatoglossal folds
• Tonsillectomy: CN IX deep to bed → taste/sensation post ⅓ + referred ear pain; rare but serious = ICA

Tongue & floor of mouth

• Genio = protrude · hyo = retrude + depress · stylo = retrude + elevate · palato (X) = elevate posterior
• Hyoglossus sandwich: XII (+ lingual n., duct) lateral · lingual a. deep → ligate for tongue-base cancer / free flap
• On hyoglossus sup→inf: lingual n. (ganglion hangs) → duct → XII
• Mylohyoid line: 2nd/3rd molar roots below → submandibular space → Ludwig’s angina (airway)
• Lingual n. at 3rd molar (soft tissue): lose sensation + taste ant ⅔ + saliva
• Unconscious: tongue falls back → jaw thrust
• Tongue lymph: tip → submental · lateral → submandibular/jugulodigastric · posterior → deep cervical

Salivary glands

Face & infratemporal fossa

• Danger triangle: facial v. → angular v. → superior ophthalmic v. → cavernous sinus (valveless) → CN VI first
• SCALP: skin, connective, aponeurosis (epicranial), loose CT (danger layer), pericranium
• Maxillary a. 1st part: middle meningeal (foramen spinosum), inferior alveolar · 3rd: sphenopalatine, descending palatine, infraorbital
• Mental foramen below lower 2nd premolar · IAN block at mandibular foramen also numbs lingual n.
• Lateral pterygoid = only opener (protrudes); others close
• Buccal branch VII = buccinator (motor) ≠ buccal n. V3 (sensory)

Cranial cavity

• Middle meningeal a. → EPIDURAL (lens, pterion); bridging veins → subdural
• Sinuses = where dural layers don’t fuse; valveless · falx = L/R; tentorium = up/down
• Cavernous sinus: VI + ICA inside; III, IV, V1, V2 in the lateral wall; V3 not
• Hutchinson sign: shingles on nose tip (external nasal, V1) → eye involvement

Orbit

• H-test: abduct → test recti; adduct → test obliques. SR+IR adduct; SO+IO abduct; “superiors intort”
• CN III palsy: down & out, ptosis, dilated pupil · IV: can’t look down when adducted · VI: can’t abduct
• Only parasympathetics synapse in the ciliary ggl; long ciliary (nasociliary) → dilator
• Tears: gland → canaliculi → lacrimal sac → nasolacrimal duct → inferior meatus
• Lacrimal gland: VII → greater petrosal → PPF ggl → zygomatic (V2) → lacrimal (V1)

Lymph

• Everything ends in deep cervical nodes (IJV) → jugular trunk → thoracic duct (L) / right lymphatic duct (R)
• Superficial cervical (EJV) ← occipital, mastoid, parotid, submandibular/submental
• Omohyoid splits superior vs inferior deep cervical; jugulodigastric = tonsillar node

Spelling watchlist

cribriform · frontonasal · sphenoethmoidal · vallecula · palatine aponeurosis · pterygoid hamulus · oropharyngeal isthmus · stylopharyngeus · hypoglossal · epicranial aponeurosis · sternocleidomastoid · arytenoid · infraglottic