ENT Anatomy Physiology

• Ear: External and Middle Ear | Inner Ear and the Eighth Nerve | Physiology of Hearing | Testing Hearing — Tuning Forks, Audiometry and Tympanometry | Physiology of Balance
• Nose and sinuses: Nose and Paranasal Sinuses | Blood Supply of the Nose — Why Noses Bleed | Nasal Physiology and Smell
• Throat and neck: Pharynx, Tonsils and Waldeyer's Ring | Larynx — Structure and Nerves | Voice, Airway Protection and Swallowing | Neck Anatomy and Lymph Node Levels | Salivary Glands | The Facial Nerve
• Pharmacology: Ear Drops and Ear Infections | Nasal Drugs and Sinusitis | Sore Throat, Vertigo and Other ENT Drugs | Ototoxic Drugs and Drug Side Effects in ENT
• Revision: ENT Anatomy and Drugs at a Glance | Spot the Diagnosis | Exam-style Scenarios | Key Points | Guidelines and Further Reading

👂 ENT anatomy, physiology and pharmacology — the foundation page for the ENT chapter. Ear, nose and throat problems make up a large share of primary care and emergency work, and most of them make sense once you know the anatomy: why children get ear infections, why noses bleed from the front, why a lung cancer causes a hoarse voice, why a parotid tumour can cause facial weakness. This page covers the structures, how hearing, balance, smell, voice and swallowing work, and the drugs used — and the drugs that damage the ear.
Your four questions for every ENT problem: Which structure is involved, and what is next to it? Which nerve carries the symptom (including referred pain)? Is the problem conductive, sensorineural, inflammatory or structural? Could a drug be causing it — or be the right treatment?

External and Middle Ear

• Pinna (auricle) — elastic cartilage covered by tightly adherent skin and perichondrium; cartilage depends on the perichondrium for blood supply — a haematoma must be drained or it causes "cauliflower ear"; perichondritis (often Pseudomonas after piercing) can destroy cartilage.
• External auditory canal — about 2.5 cm, S-shaped; lateral third cartilaginous (hair, wax glands), medial two-thirds bony (thin skin — painful); pull the pinna up and back in adults (down and back in infants) to straighten it.
• Sensory nerves of the ear — explain referred otalgia:
  • Auriculotemporal nerve (V3) — anterior canal and tragus — referred pain from teeth, TMJ.
  • Great auricular nerve (C2, C3) — lower pinna — referred pain from the neck.
  • Arnold's nerve (auricular branch of the vagus) — posterior canal — explains the cough reflex when the canal is touched; referred pain from the larynx and pharynx.
  • Glossopharyngeal nerve (Jacobson's nerve) — middle ear — referred pain from tonsils and tongue base (post-tonsillectomy otalgia; oropharyngeal cancer).
  • Facial nerve — small area of concha — vesicles in Ramsay Hunt syndrome.
• Tympanic membrane — pars tensa (most of the drum) and pars flaccida (attic — the site of cholesteatoma); landmarks — handle of malleus, umbo, cone of light (anteroinferior).
• Middle ear — air-filled space:
  • Ossicles — malleus, incus, stapes (footplate in the oval window); otosclerosis fixes the stapes footplate (conductive loss).
  • Muscles — tensor tympani (V3) and stapedius (VII) — stapedius damps loud sound; facial palsy proximal to its branch causes hyperacusis.
  • Eustachian tube — connects the middle ear to the nasopharynx; equalises pressure and drains secretions; shorter, wider and more horizontal in children — why otitis media and glue ear are common; blocked by adenoids, colds, cleft palate (Down syndrome), nasopharyngeal carcinoma (unilateral glue ear in an adult).
  • Relations — facial nerve (medial wall), chorda tympani (crosses the drum), mastoid air cells (posteriorly — mastoiditis), middle cranial fossa (above — intracranial complications), internal jugular vein (below), carotid artery (anterior).

Inner Ear and the Eighth Nerve

• Bony labyrinth (in the petrous temporal bone) containing the membranous labyrinth:
  • Perilymph — like extracellular fluid (high sodium) — between bony and membranous labyrinths.
  • Endolymph — like intracellular fluid (high potassium) — within the membranous labyrinth; excess endolymph (endolymphatic hydrops) underlies Ménière's disease.
• Cochlea — a spiral of 2.5 turns; the organ of Corti on the basilar membrane:
  • Inner hair cells — the true sensory cells (about 3,500) — signal to the auditory nerve.
  • Outer hair cells — amplify quiet sounds by contracting — produce otoacoustic emissions (the basis of newborn hearing screening); damaged first by noise, ototoxic drugs and ageing.
  • Tonotopic — the base detects high frequencies, the apex low frequencies — the base is damaged first (high-frequency loss in presbycusis, noise and ototoxicity).
• Vestibular system:
  • Semicircular canals (anterior, posterior, lateral) — detect rotational (angular) acceleration; the posterior canal is the commonest site of BPPV (displaced otoconia).
  • Utricle and saccule (otolith organs) — detect linear acceleration and gravity using calcium carbonate crystals (otoconia).
• Vestibulocochlear nerve (VIII) — cochlear and vestibular divisions travel with the facial nerve through the internal acoustic meatus to the cerebellopontine angle — vestibular schwannoma causes unilateral hearing loss and tinnitus (and later facial and trigeminal symptoms).
• Central auditory pathway — cochlear nuclei → superior olive → inferior colliculus → medial geniculate body → auditory cortex (temporal lobe); bilateral representation — a unilateral cortical lesion doesn't cause deafness.
• Blood supply — labyrinthine artery (usually from AICA) — an end artery — vascular occlusion causes sudden hearing loss and vertigo (AICA stroke).

Physiology of Hearing

• Sound — pressure waves; humans hear about 20–20,000 Hz; speech mainly 500–4,000 Hz; loudness in decibels (dB — logarithmic: +10 dB is 10 times the intensity).
• Conduction pathway — pinna and canal (collect and amplify around 2–4 kHz) → tympanic membrane → ossicles → oval window → cochlear fluid wave → basilar membrane movement → hair cell deflection → potassium influx from endolymph → depolarisation → auditory nerve.
• Impedance matching — the middle ear overcomes the air-to-fluid mismatch: the large drum area focused on the small stapes footplate (about 17:1) plus the ossicular lever — together about a 25–30 dB gain; loss of this (perforation, ossicular damage) causes conductive hearing loss of up to about 60 dB.
• Types of hearing loss:
  • Conductive — outer or middle ear — wax, otitis externa, glue ear, otitis media, perforation, otosclerosis, cholesteatoma, ossicular disruption.
  • Sensorineural — cochlea or nerve — presbycusis, noise, ototoxic drugs, Ménière's, vestibular schwannoma, infections (meningitis, CMV, mumps, measles), genetic (GJB2), sudden sensorineural hearing loss (emergency).
  • Mixed.
• Presbycusis — age-related, bilateral, symmetrical, high-frequency loss — difficulty with speech in background noise; hearing aids; hearing loss is a major modifiable risk factor for dementia.
• Noise-induced hearing loss — characteristic "notch" at 4 kHz on the audiogram; prevention — hearing protection (workplace noise regulations).
• Tinnitus — perception of sound without an external source; usually with hearing loss; unilateral or pulsatile tinnitus needs investigation (vestibular schwannoma; vascular causes — dural AV fistula, glomus tumour, idiopathic intracranial hypertension).

Testing Hearing — Tuning Forks, Audiometry and Tympanometry

• Tuning fork tests (512 Hz):

  	Rinne (each ear)	Weber (forehead)
  Normal	Air conduction louder than bone ("positive")	Central
  Conductive loss (e.g. left)	Bone louder than air on the left ("negative")	Lateralises to the affected (left) ear
  Sensorineural loss (e.g. left)	Air louder than bone on both sides (reduced on left)	Lateralises to the good (right) ear

• Pure tone audiometry — thresholds (dB) across frequencies for air and bone conduction:
  • Air–bone gap — conductive loss.
  • Air and bone both reduced together — sensorineural.
  • Asymmetric sensorineural loss (e.g. 15 dB or more difference at two adjacent frequencies) — MRI internal acoustic meatus (vestibular schwannoma).
  • Normal hearing — thresholds about 20 dB or better.
• Tympanometry — measures drum mobility and middle ear pressure:
  • Type A — normal.
  • Type B — flat — fluid (glue ear), perforation or grommet (large canal volume), wax.
  • Type C — negative pressure — Eustachian tube dysfunction.
• Otoacoustic emissions and auditory brainstem response — newborn hearing screening and objective testing.
• Speech audiometry — word recognition (poor out of proportion to thresholds — retrocochlear disease).

Physiology of Balance

• Balance depends on three inputs — vestibular, visual and proprioceptive — integrated in the brainstem and cerebellum; failure of one can be compensated by the others (and older people with several deficits fall).
• Vestibulo-ocular reflex (VOR) — keeps the eyes steady on a target when the head moves (vestibular nuclei → III, IV, VI via the medial longitudinal fasciculus); tested by the head impulse test — a corrective saccade indicates a peripheral vestibular lesion.
• Nystagmus:
  • Peripheral (vestibular neuritis) — horizontal (with torsional component), fast phase away from the affected side, suppressed by visual fixation, unidirectional.
  • Central (stroke, MS) — vertical, purely torsional, direction-changing (gaze-evoked), not suppressed by fixation.
  • BPPV — torsional upbeating nystagmus with latency and fatigue on the Dix–Hallpike test (posterior canal).
• HINTS examination (in continuous vertigo with nystagmus) — Head Impulse, Nystagmus, Test of Skew — a normal head impulse, direction-changing nystagmus or skew deviation suggests stroke.
• Vestibular compensation — the brain adapts after a vestibular loss; vestibular sedatives delay compensation — use for a few days only; vestibular rehabilitation exercises help.
• Vertigo by timing:
  • Seconds, positional — BPPV.
  • Minutes to hours, recurrent, with hearing loss, tinnitus and aural fullness — Ménière's disease; without — vestibular migraine.
  • Days, single episode — vestibular neuritis (with hearing loss — labyrinthitis) or posterior circulation stroke.

Nose and Paranasal Sinuses

• Nasal septum — septal cartilage (front), perpendicular plate of ethmoid and vomer (back); septal haematoma after trauma must be drained (cartilage necrosis — saddle nose; abscess).
• Lateral nasal wall — three turbinates (conchae) with meatuses beneath:

  Opening	What drains there
  Inferior meatus	Nasolacrimal duct (tears — why crying gives a runny nose)
  Middle meatus (osteomeatal complex)	Maxillary, frontal and anterior ethmoid sinuses — blockage here drives most chronic rhinosinusitis
  Superior meatus	Posterior ethmoid sinuses
  Sphenoethmoidal recess	Sphenoid sinus

• Paranasal sinuses — air-filled spaces that lighten the skull and add resonance:
  • Maxillary and ethmoid — present at birth; frontal — develops from about age 6–8 (not seen on imaging in young children); sphenoid — later childhood.
  • Ethmoid sinuses are separated from the orbit by the thin lamina papyracea — orbital cellulitis in children is usually from ethmoiditis.
  • Maxillary sinus — roots of the upper teeth lie in its floor (dental sinusitis, oroantral fistula after extraction); infraorbital nerve in the roof (numb cheek after fracture or tumour).
  • Frontal sinus — infection can spread to the brain (abscess) or bone (Pott's puffy tumour).
  • Sphenoid sinus — next to the pituitary, optic nerves, cavernous sinus and carotid arteries — route for transsphenoidal pituitary surgery.
• Cribriform plate (roof of the nasal cavity) — carries olfactory fibres; fractures cause CSF rhinorrhoea and anosmia; nasal polyps in a child — think cystic fibrosis; unilateral polyp or mass in an adult — exclude tumour.

Blood Supply of the Nose — Why Noses Bleed

• Rich blood supply from both carotid systems:
  • Internal carotid — via the ophthalmic artery → anterior and posterior ethmoidal arteries.
  • External carotid — via the maxillary artery → sphenopalatine artery (the main supply — posterior bleeds) and greater palatine artery; via the facial artery → superior labial artery.
• Little's area (Kiesselbach's plexus) — the anterior septum where these vessels meet — the source of about 90% of nosebleeds; easily reached for pressure (pinch the soft part of the nose, lean forward, 10–15 minutes) and cautery (silver nitrate).
• Posterior bleeds (sphenopalatine territory, Woodruff's plexus) — older people, hypertension, anticoagulants — heavier, harder to control — packing, endoscopic sphenopalatine artery ligation, or embolisation.
• Ethmoidal artery ligation — for bleeds from the ethmoidal territory (ICA system — embolisation is avoided because of stroke and blindness risk).
• Risk factors — nose picking, dry air, URTI, trauma, anticoagulants and antiplatelets, hypertension (association), HHT (see Genetics chapter), tumours (unilateral bleeding with obstruction — juvenile angiofibroma in adolescent boys, sinonasal malignancy).
• Venous drainage — facial vein and ophthalmic veins connect with the cavernous sinus — infections of the "danger triangle" (upper lip and nose) can cause cavernous sinus thrombosis.

Nasal Physiology and Smell

• Functions of the nose — warming, humidifying (nearly 100% by the nasopharynx) and filtering air; smell; resonance of voice; immune defence (IgA, mucus).
• Mucociliary clearance — ciliated respiratory epithelium moves the mucus blanket backwards to the nasopharynx to be swallowed; impaired in primary ciliary dyskinesia (Kartagener's — sinusitis, bronchiectasis, situs inversus), cystic fibrosis, smoking, dry air.
• Nasal cycle — alternating congestion of each side every few hours (normal) — noticed when one side is already narrowed (deviated septum).
• Nasal resistance — the nose provides about half of total airway resistance; neonates are obligate nasal breathers (bilateral choanal atresia is an emergency — cyanosis relieved by crying).
• Smell (olfaction) — olfactory epithelium at the roof of the nose → olfactory nerve fibres through the cribriform plate → olfactory bulb → olfactory cortex (no thalamic relay); flavour depends largely on smell.
• Causes of smell loss (anosmia):
  • Conductive — nasal polyps, chronic rhinosinusitis, rhinitis.
  • Sensorineural — post-viral (including COVID-19), head injury (shearing at the cribriform plate), ageing, Parkinson's disease and Alzheimer's (early sign), Kallmann syndrome (anosmia with hypogonadotropic hypogonadism), tumours (olfactory groove meningioma), drugs, smoking.
• Smell training — repeated sniffing of set odours — helps post-viral smell loss.
• Parosmia (distorted smell) and phantosmia (phantom smells — temporal lobe seizures, or recovering post-viral loss).

Pharynx, Tonsils and Waldeyer's Ring

• Pharynx — muscular tube from the skull base to the cricoid (C6), continuous with the oesophagus:
  • Nasopharynx — behind the nose — adenoids, Eustachian tube openings, fossa of Rosenmüller (commonest site of nasopharyngeal carcinoma — EBV, South-East Asian ancestry).
  • Oropharynx — behind the mouth — palatine tonsils, tongue base, soft palate — HPV-related oropharyngeal cancer (rising — younger non-smokers; better prognosis).
  • Hypopharynx (laryngopharynx) — around the larynx — piriform fossae (cancers present late; fish bones lodge here), post-cricoid region (post-cricoid web — iron deficiency, Plummer–Vinson syndrome).
• Waldeyer's ring — a ring of lymphoid tissue guarding the upper aerodigestive tract — adenoids (nasopharyngeal tonsil), palatine tonsils, lingual tonsil, tubal tonsils; most active in childhood, shrinks after puberty.
  • Adenoid hypertrophy — nasal obstruction, mouth breathing, snoring and obstructive sleep apnoea, glue ear.
  • Unilateral tonsillar enlargement in an adult — exclude lymphoma or squamous cell carcinoma.
• Tonsil blood supply — mainly the tonsillar branch of the facial artery; the paratonsillar vein is the usual source of post-tonsillectomy bleeding (primary within 24 hours; secondary at 5–10 days — infection).
• Peritonsillar space — quinsy (peritonsillar abscess) — trismus (medial pterygoid irritation), uvula deviation, "hot potato" voice.
• Deep neck spaces — parapharyngeal and retropharyngeal spaces — infection can spread to the mediastinum (descending mediastinitis); retropharyngeal abscess in young children.
• Killian's dehiscence — a weak area between the thyropharyngeus and cricopharyngeus parts of the inferior constrictor — site of a pharyngeal pouch (Zenker's diverticulum — older people: regurgitation of undigested food, halitosis, gurgling neck).
• Nerve supply — sensation from the glossopharyngeal (IX) (oropharynx — gag reflex afferent) and vagus (X) (hypopharynx — gag efferent); referred otalgia via IX and X.

Larynx — Structure and Nerves

• Cartilages — thyroid (Adam's apple), cricoid (the only complete ring — at C6; cricoid pressure), paired arytenoids (move the vocal folds), epiglottis (elastic cartilage — covers the inlet in swallowing).
• Regions — supraglottis (epiglottis to false cords), glottis (true vocal folds), subglottis (below the cords to the cricoid).
  • Narrowest part — the glottis in adults, the subglottis (cricoid ring) in young children — small swelling causes major obstruction (croup, subglottic stenosis after intubation).
  • Lymphatic drainage — glottis has very few lymphatics — glottic cancers metastasise late and present early (hoarseness) — good prognosis; supraglottic cancers spread early to nodes.
• Cricothyroid membrane — between thyroid and cricoid cartilages — site for emergency front-of-neck access ("can't intubate, can't oxygenate" — scalpel cricothyroidotomy).
• Nerve supply (branches of the vagus):

  Nerve	Supplies
  Superior laryngeal — internal branch	Sensation above the vocal folds (cough reflex)
  Superior laryngeal — external branch	Cricothyroid muscle — tenses the cords (pitch) — injury in thyroid surgery causes loss of high notes and voice fatigue
  Recurrent laryngeal nerve	All other intrinsic muscles (including posterior cricoarytenoid — the only abductor) and sensation below the cords

• Recurrent laryngeal nerve course:
  • Left — loops under the aortic arch — longer and more often damaged: lung cancer (left hilum, mediastinal nodes), aortic aneurysm, enlarged left atrium (mitral stenosis — Ortner's syndrome), oesophageal cancer, cardiothoracic surgery.
  • Right — loops under the right subclavian artery — right apical lung cancer.
  • Both — thyroid surgery and thyroid cancer.
• Vocal cord palsy — unilateral — hoarse, breathy voice, weak cough, aspiration; bilateral — cords lie near the midline — stridor with a near-normal voice (airway emergency).
• Persistent hoarseness over 3 weeks — especially in smokers — laryngoscopy (suspected cancer pathway at 45 and over — NICE NG12); chest X-ray to look for a lung cancer affecting the left RLN.

Voice, Airway Protection and Swallowing

• Functions of the larynx — airway protection (most important), breathing, phonation, raising intrathoracic and intra-abdominal pressure (cough, straining, lifting — Valsalva).
• Phonation — air from the lungs passes through adducted vocal folds; the folds vibrate (mucosal wave — Bernoulli effect); pitch depends on cord tension and length (cricothyroid); the pharynx, mouth and nose shape the sound (articulation and resonance).
  • Hoarseness causes — laryngitis, voice overuse (nodules — "singer's nodules"), smoking (Reinke's oedema, leukoplakia, cancer), reflux, cord palsy, hypothyroidism, inhaled steroids (candida, myopathy — rinse mouth), muscle tension dysphonia, neurological disease.
• Airway protection — closure of the vocal and false cords, epiglottic tilt, laryngeal elevation and the cough reflex.
• Phases of swallowing:
  1. Oral preparatory and oral phase (voluntary) — chewing (V), lip seal (VII), tongue moves the bolus back (XII).
  2. Pharyngeal phase (reflex — under 1 second) — soft palate seals the nasopharynx, the larynx rises and closes, the epiglottis tilts, breathing stops, pharyngeal constrictors push the bolus, the upper oesophageal sphincter (cricopharyngeus) relaxes (IX, X; brainstem swallowing centre).
  3. Oesophageal phase — peristalsis; lower oesophageal sphincter relaxes.
• Oropharyngeal dysphagia — difficulty starting a swallow, coughing or choking, nasal regurgitation — stroke, Parkinson's, MND, myasthenia, dementia, head and neck cancer; silent aspiration is common — bedside swallow screen after stroke, speech and language therapy, videofluoroscopy or FEES.
• Oesophageal dysphagia — food sticking after swallowing — strictures, cancer, achalasia, eosinophilic oesophagitis (see Gastroenterology chapter).
• Globus — a lump-in-the-throat sensation between meals without dysphagia — usually benign; red flags (dysphagia, weight loss, pain, hoarseness, neck lump) need investigation.

Neck Anatomy and Lymph Node Levels

• Triangles — the sternocleidomastoid divides the neck into:
  • Anterior triangle — submandibular, submental, carotid and muscular triangles — thyroid, larynx, carotid sheath (common and internal carotid arteries, internal jugular vein, vagus nerve), submandibular gland.
  • Posterior triangle — accessory nerve (XI — damaged in node biopsy: shoulder drop, trapezius weakness), brachial plexus roots, subclavian artery, lymph nodes.
• Cervical lymph node levels (for describing nodes and planning neck dissection):

  Level	Site	Typical drainage
  I	Submental (Ia) and submandibular (Ib)	Lip, floor of mouth, anterior tongue, face
  II	Upper jugular (jugulodigastric)	Oropharynx, tonsils, nasopharynx, parotid — "tonsillar node"
  III	Middle jugular	Larynx, hypopharynx
  IV	Lower jugular	Larynx, hypopharynx, thyroid, oesophagus
  V	Posterior triangle	Nasopharynx, scalp, skin
  VI	Central (pre- and paratracheal)	Thyroid, larynx

• Left supraclavicular node (Virchow's node) — Troisier's sign — metastasis from abdominal cancers (stomach) via the thoracic duct.
• Neck lumps by position:
  • Midline — thyroid (moves with swallowing), thyroglossal duct cyst (moves up with tongue protrusion — remnant of thyroid descent from the foramen caecum), dermoid cyst.
  • Anterior triangle — branchial cyst (young adult, anterior border of SCM — but a "cyst" in an adult over 40 may be a cystic nodal metastasis from HPV oropharyngeal cancer), carotid body tumour (pulsatile, moves side to side not up and down, splays the carotid bifurcation), submandibular gland, lymph nodes.
  • Posterior triangle — lymph nodes (nasopharyngeal cancer, lymphoma, TB), cystic hygroma (infants — transilluminates), cervical rib.
• Thyroid anatomy — two lobes and an isthmus over tracheal rings 2–4; superior thyroid artery (with the external laryngeal nerve) and inferior thyroid artery (with the recurrent laryngeal nerve); parathyroid glands behind (hypocalcaemia after thyroidectomy).

Salivary Glands

• Saliva — 1–1.5 L a day — lubrication, digestion (amylase, lipase), antimicrobial (IgA, lysozyme), buffering (protects teeth), taste.
• Parotid gland:
  • Largest; mainly serous saliva; duct (Stensen's) opens opposite the upper second molar.
  • The facial nerve runs through it (dividing it into superficial and deep lobes) — a parotid mass with facial weakness suggests malignancy; parotid surgery risks facial palsy.
  • Secretomotor supply — glossopharyngeal (IX) → otic ganglion → auriculotemporal nerve — Frey's syndrome (gustatory sweating) after parotidectomy from misdirected regrowth.
  • Tumours — about 80% of salivary tumours occur in the parotid and about 80% of these are benign (pleomorphic adenoma — commonest; Warthin's tumour — older male smokers, bilateral).
  • Swelling — mumps, sialadenitis (dehydrated post-operative patients), Sjögren's, sarcoid, HIV, alcohol, bulimia.
• Submandibular gland:
  • Mixed serous and mucous saliva (most resting saliva); duct (Wharton's) opens beside the frenulum.
  • About 80% of salivary stones occur here (more viscous, alkaline saliva, uphill duct) — pain and swelling at mealtimes.
  • Secretomotor supply — facial nerve (VII) via the chorda tympani → submandibular ganglion.
  • Nerves at risk in surgery — marginal mandibular branch of VII (lower lip weakness), lingual nerve (tongue numbness), hypoglossal nerve (tongue deviation).
  • Tumours are more often malignant (about 50%) than parotid tumours.
• Sublingual and minor salivary glands — mucous; tumours here are usually malignant; ranula (sublingual mucous cyst).
• Dry mouth (xerostomia) — drugs (anticholinergics, antidepressants, diuretics, opioids), Sjögren's, radiotherapy, dehydration, diabetes.

The Facial Nerve

• Functions — motor to muscles of facial expression and stapedius; taste from the anterior two-thirds of the tongue (chorda tympani); parasympathetic to lacrimal, submandibular and sublingual glands; small sensory area of the ear.
• Course and branches (localising a lesion):
  1. Pons → cerebellopontine angle → internal acoustic meatus (with VIII).
  2. Facial canal in the temporal bone — geniculate ganglion → greater petrosal nerve (tear production).
  3. Branch to stapedius (hyperacusis if lost).
  4. Chorda tympani (taste and salivation) crosses the middle ear.
  5. Exits the stylomastoid foramen → enters the parotid → five branches — temporal, zygomatic, buccal, marginal mandibular, cervical ("To Zanzibar By Motor Car").
• Upper vs lower motor neurone lesions:
  • UMN (stroke) — forehead spared (the upper face has bilateral cortical supply).
  • LMN (Bell's palsy, parotid tumour, temporal bone fracture, Ramsay Hunt, cholesteatoma, Lyme disease, sarcoidosis, GBS) — whole side of the face, including the forehead.
• Bell's palsy — acute idiopathic LMN palsy — prednisolone within 72 hours (e.g. 50 mg daily for 10 days or 60 mg tapering — check local guidance); eye protection (lubricants, taping at night — corneal exposure); most recover in weeks to months.
• Ramsay Hunt syndrome (VZV of the geniculate ganglion) — painful ear, vesicles in the ear canal or palate, LMN facial palsy, often hearing loss and vertigo — aciclovir or valaciclovir plus prednisolone; worse prognosis than Bell's.
• House–Brackmann scale (I normal to VI complete palsy) grades severity.
• Bilateral facial palsy — GBS, sarcoidosis, Lyme disease, HIV, leukaemia — investigate.

Ear Drops and Ear Infections

• Ear wax — normal and self-cleaning; softening drops (olive oil, almond oil — avoid with nut allergy, sodium bicarbonate) for 3–5 days; irrigation or microsuction if needed; don't use cotton buds.
• Acute otitis externa (NICE CKS):
  • Aural toilet (microsuction) is often the most important treatment; a wick if the canal is very swollen.
  • Mild — acetic acid 2% spray.
  • Moderate or severe — topical antibiotic with or without steroid for 7 days (up to 14) — e.g. neomycin- or gentamicin-containing drops, or ciprofloxacin drops.
  • Perforated drum or unknown status — avoid aminoglycoside drops (ototoxicity — manufacturers contraindicate) — use a quinolone (ciprofloxacin) instead; ENT may use short supervised aminoglycoside courses in infected ears.
  • Fungal otitis externa (white or black debris after antibiotic drops) — clotrimazole solution.
  • Oral antibiotics (flucloxacillin) only for spreading cellulitis.
• Necrotising (malignant) otitis externa — older people with diabetes or immunosuppression; severe pain, granulation tissue at the bony–cartilaginous junction, cranial nerve palsies — Pseudomonas skull base osteomyelitis — urgent ENT, CT or MRI, prolonged IV anti-pseudomonal antibiotics (e.g. ceftazidime, ciprofloxacin).
• Acute otitis media (NICE NG91):
  • Usually self-limiting (3–7 days) — analgesia (paracetamol, ibuprofen); no or back-up antibiotic for most.
  • Immediate antibiotics — systemically unwell, high risk of complications, under 2 with bilateral infection, otorrhoea (perforation).
  • First line — amoxicillin for 5–7 days; penicillin allergy — clarithromycin (or erythromycin in pregnancy).
  • Analgesic ear drops (phenazone and lidocaine) may help if the drum is intact.
• Glue ear (otitis media with effusion) — active observation for 3 months; hearing aids or grommets; antibiotics, decongestants and antihistamines don't help.
• Chronic suppurative otitis media — aural toilet and topical quinolone drops; ENT review for cholesteatoma.