Pocket tutor: Otolaryngology Sonna Ifeacho, Henry Zhang, Abir Bhattacharyya
Note: Page numbers in bold or italic refer to tables or figures respectively.
Abducens nerve (CN VI) 33
Accessory auricles 2
Accessory nerve (CN XI) 35
Achalasia 177
Ramsay Hunt syndrome 109
sensorineural hearing loss 126
Acid reflux 49
Acoustic neuroma 115, 127 see also Vestibular schwannomas (VS)
Acoustic reflex 1011
Acute diffuse otitis externa 8184, 82
Acute localised otitis externa (furuncle) 83
Acute mastoiditis 231
Acute otitis media 96, 96
bulging tympanic membrane due to 96
in children 9799
clinical features 98, 98
complications 99100, 100
and ear pain 43
non-suppurative 96
predisposing factors 97
recurrent 96
suppurative 96
treatment 9899
Acute otitis media with mastoiditis, in children 229231, 230
Acute suppurative otitis media 83
Acute vestibular failure
nystagmus in 88
and vertigo 8789
Adenoidectomy 99
Adenotonsillar disease, in children 238242
blood tests 240
causes of tonsillitis 239
Centor clinical prediction score 241
management 241242
and obstructive sleep apnoea 239, 240
signs and symptoms 240
sleep study 240
throat swabs 240
tonsillectomy 241
white spots, in acute tonsillitis 239
Adenotonsillar hypertrophy 262
Airway compromise, in adult 181183
differential diagnosis 182183
microlaryngoscopy 182, 182
squamous cell carcinoma of larynx and 183
Airways, in child 51
Airway trauma, and airway obstruction 183
Allergic rhinitis 47
Amitriptyline, for midfacial segment pain 142
Amoxicillin–clavulanic acid, for acute otitis media 99
Amoxicillin, for acute otitis media 99
Anaphylaxis, and airway obstruction 183
Ankylosing rheumatoid arthritis 87
Anosmia 48, 140
acute otitis media 99
chronic otitis media 103104
chronic rhinosinusitis 150
necrotising otitis externa 91, 92
otitis media 231
salivary gland diseases 210
tonsillitis 188189
Antihistamines, for rhinitis 146, 150
Antihistamine sprays 146
Antimicrobial and steroidal ear drops
chronic otitis media 103
otitis externa 94
Antipneumococcal vaccine, for tonsillitis prevention 189
Antrochoanal polyps 138, 151
Aphonia 198
Apnoea–hypopnoea index (AHI) 224
Arytenoid granuloma 183
Aspergillus niger 83
Audiological tests
pure tone audiometry 7273, 73
tympanometry 73, 74
Auditory brainstem response (ABR) 247248
Auditory pathway 8
Aural fullness and facial weakness 46
Azithromycin, for acute otitis media 99
Bacterial tonsillitis
in children 231234
with parapharyngeal cellulitis or abscess 233
with peritonsillar cellulitis or abscess 233
with retropharyngeal cellulitis or abscess 233234
Balance, physiology of 13, 1315
Balloon sinuplasty, in chronic rhinosinusitis 150
Barany noise box 55
Bartonella henselae 179
Basilar membrane 11
Bell's palsy 46, 108 see also Facial palsy
Benign lesions, and hoarseness 175, 175
Benign oesophageal strictures 177
Benign paroxysmal positional vertigo (BPPV) 88, 120124
abnormal particle movement in semicircular canal in 120
Brandt–Daroff home exercises 124
canalith repositioning for 123124
as cause of vertigo 120, 121
classic 120
Epley's manoeuvre 123124
Hallpike's manoeuvre 122, 122
investigation and diagnosis 122, 122123
medical treatment 124
nystagmus with 121
rotational chair and home devices 124
Semont manoeuvre 124
Benzylpenicillin, for bacterial tonsillitis 234
Bernoulli principle 37, 38
Betahistine 119
Bilateral vocal fold palsy, and airway obstruction 183
Bone-anchored hearing aid (BAHA) 112
BPPV see Benign paroxysmal positional vertigo (BPPV)
Brain abscess 100
Branchial cyst 213, 214
Brandt–Daroff home exercises 124
Cacosmia 140
Candida albicans 83
Carotid arteries 17
external 18
internal 18
Carotid body tumour 181
Carotid sheath
neck 22
space 25, 27
Carotid triangle 22, 23
Catarrhal child 254258
causes 255
clinical features 256
investigations 256, 257
management principles 257258
Cat scratch disease 179
Cauliflower ear 129130
Cefuroxime, for acute otitis media 99
Central hyposmia 139
Cerebellar infarction 89
Ceruminous glands 3
Choanal atresia 51, 262
Cholesteatoma 104
discharge in 45
Chorda tympani 6
Chorda tympani nerve 36
Chronic otitis externa 83
Chronic otitis media 100104, 231
active squamous 104
causative organisms 101
clinical features 101, 102
complications 104, 105
management 102104
microscopic examination of ear 101102, 103
Chronic rhinosinusitis 147150
clinical features 147148, 149
investigation 148149
with nasal polyposis 147
pathogenesis 147, 148
treatment 150, 150
Cinnarizine 119
Clarithromycin, for acute otitis media 99
Cochlea 7, 8
Collagen vascular disorders 177
Compound action potential 21
Conductive deafness 54
Conductive hyposmia 139
Congenital cholesteatoma 87
Congenital ear deformities 249254
clinical features 252, 252
investigations 252, 253
microtia 249, 251, 251, 254
preauricular sinus or tags 249, 250, 251, 253
prominent ears 249, 250, 251, 252253
Congenital hearing loss 50
Contact ulcers 200
Corneal reflex 69
testing 69, 69
Corroding watch battery 259
chronic otitis media 104
chronic rhinosinusitis 150
nasal polyps 152153
tonsillitis 188
Cranial nerves 32, 3335
Cricoarytenoid ankylosis 183
Cricopharyngeal muscle spasms 49
Croup 262
CSF rhinorrhoea 47
Cupula 14
Cystic fibrosis 137
Deafness, otosclerosis and 8487
Diagnostic algorithm 75
facial weakness 76
hoarseness 77
nasal obstruction 79
otorrhoea 78
Digastric triangle 22, 23
Distraction test 248
Diuretics, for Ménière's disease 119
Double vision 46
Drug-induced hyposmia/dysosmia 139
Dysphagia 49, 176, 185
barium swallow 176177, 177
differential diagnosis 177178
malignant oesophageal strictures and 176178
Earache (otalgia)
acute diffuse otitis externa and 8184, 82
causes of 4344, 44
Ear, anatomy of 1, 1
inner ear 2, 79, 8
middle ear 2, 46, 5
outer ear 1, 23
tympanic membrane 4, 5
Ear, clinical examination of 5154
deafness, assessment of 5458
facial nerve assessment 5859, 60
fistula test and pneumatic otoscopy 59, 61
osteoma of ear canal 52, 53
otoscope for, use of 5152, 53
tympanic membrane 5253, 54
Ear discharge (otorrhoea)
differential diagnosis 9091
necrotising ‘malignant’ otitis externa and 9092
Ear trauma see Trauma to ear
Eczematous otitis externa 83
Endolymph 7
Endolymphatic hydrops 116
ENT instrument tray 52
Epiglottitis 262
Epistaxis 18, 50, 133135, 134, 154160
airway, breathing and circulation 157
anterior 135, 154, 156
blood tests 157
causes 134135, 155, 155156, 156
conservative management 157
in elderly patient 135
history taking in 4748
and iron deficiency anaemia 156
nasal packing 158159
posterior 154, 156
recurrent 156, 157
silver nitrate nasal cautery 158
surgical management 159
Epley's manoeuvre 123124
Epworth sleepiness scale (ESS) 224
Ethmoidal infection 18
Eustachian tube 6, 235
blockage 7
Excitatory postsynaptic potentials (EPSPs) 12
External auditory canal (EAC) 1, 1, 2
Facial asymmetry 44, 46
Facial nerve (CN VII) 6, 34, 40 see also Facial palsy
assessment 5859, 60
Facial nerve palsy 46, 100
Facial pain 47, 140142
differential diagnosis 141142
Facial palsy 104110
in acute or chronic otitis media 107108
causes 104, 107
course and branches of facial nerve 106, 106
idiopathic 108
investigations 107
Facial weakness 46
diagnostic algorithm for 76
First branchial cleft anomaly 252
Fistula test 59
Flexible laryngoscope, use of 65
Flexible nasendoscopy 63, 65
Follicular thyroid cancer 205
Foreign bodies in ear, nose and throat
in children 258261
first attempt as best attempt 259
foreign bodies in ear 260
foreign bodies in throat 260, 260261
neck and chest radiographs 259
Foreign body
and airway obstruction 183
in nose 227229, 228
Frey's syndrome 210
Frontal sinusitis 47
Functional endoscopic sinus surgery 150
Fungal otitis externa 95
Gabapentin, for midfacial segment pain 142
Gastro-oesophageal reflux disease (GORD) 49
Gentamicin, for Ménière's disease 119
Globus pharyngeus 49, 178, 190192
advice and medical treatment 191192
barium swallow 191
causes 190, 190
laryngopharyngeal reflux and 190, 190
transnasal oesophagoscopy (TNO) 191
Glomus tympanicum tumour 87
Glossopharyngeal nerve (CN IX) 34, 37
Glottis 28, 29
lymphatic drainage of 30
GPA see Granulomatosis with polyangiitis (GPA)
Granulomatosis with polyangiitis (GPA) 163 see also Granulomatous conditions of nose and paranasal sinuses
Granulomatous condition, of middle ear 91
Granulomatous conditions of nose and paranasal sinuses 163167
biopsy 166
blood tests 166
causes 164, 164
chest X-ray 166
clinical features 165, 165
culture and sensitivity 166
granulomatosis with polyangiitis 163, 165, 165
sarcoidosis 163164, 165
treatment 166
Group A beta-haemolytic streptococcal (GABHS) infection 241
Gustatory sweating 210
Haematological investigations 6970, 71
Hair cells 7
inner 7
outer 7
Halitosis (bad breath) 49
Hallpike's manoeuvre 122, 122
Head and neck 2122
anatomical levels of neck 23, 24, 24
anterior triangle of neck 22, 2223
fascia of neck 22
neck spaces and infections 25, 2627
posterior triangle of neck 22, 23
Head and neck cancer
larynx 218221
oropharynx 215218
Head and neck examination 66
lump in neck 66
palpation of neck 66, 67
thyroid status 6667
Head and neck pathology, cardinal presentations in 48
acid reflux and heartburn 49
dysphagia 49
globus pharyngeus 49
halitosis 49
hoarseness or change in voice 48
snoring 50
sore throat 48
stridor and stertor 50
swelling of neck 4950
Hearing aids
Ménière's disease 119
otitis media with effusion 237
otosclerosis 112
presbyacusis 115116
Hearing, clinical assessment of 5458
free field speech testing 55
history-taking 5455
tuning fork tests 5558
type and degree of deafness by 54
Hearing loss 44, 45
conductive 45
nature of 45
paediatric (see Paediatric hearing loss)
sensorineural 45
Hearing, physiology of 9
inner ear 1112
middle ear 911, 10, 11
outer ear 9
Hereditary haemorrhagic telangiectasia 156, 156
Herpes zoster oticus see Ramsay Hunt syndrome
Histological/cytopathological investigations 72
History taking 43
in children 5051
in ear disease 4346, 44
in head and neck pathology 4850
in nasal and sinus pathology 4648
Hoarseness (dysphonia) 48, 173
diagnostic algorithm 77
differential diagnosis 174175, 175
glottal tumours and 173176
microlaryngoscopy 174, 174
vocal fold lesions and 195
Hot potato voice 186 see also Tonsillitis and peritonsillar abscess
Hyperosmia 140
Hypogeusia 37
Hypoglossal nerve (CN XII) 35, 40
palsy 90, 91
Hyposmia 48, 138, 140
differential diagnosis 139
sensorineural hyposmia following trauma 138140
Iatrogenic injury 109110
Imaging modalities 70
CT scanning 70, 72
MRI scanning 70, 72
MRI with gadolinium contrast 72
plain radiography 70, 72
ultrasound 72
Immunotherapy, in rhinitis 146
Impedance audiometry see Tympanometry
Incus 5
Infectious mononucleosis 189
Inferior cornu 31
Inferior turbinate hypertrophy 153, 154
Inner ear 2, 79, 8
auditory pathway 8
cochlea 7, 8
embryology 2
physiology of hearing 1112
semicircular canals 78
vestibular pathway 89
vestibule 7
Instruments, for clinical examination 52
Intranasal steroids, in rhinitis 145146
Inverted papilloma 153
Investing fascia, neck 22
Juvenile nasopharyngeal angiofibroma 153
Kiesselbach's plexus 17, 17, 156
Killian's dehiscence 25, 192
Labyrinthine infarction 89
Labyrinthitis 100
Lamina papyracea 18
Laryngeal cancers 218221
glottic cancer 218
hoarseness in glottic cancers 219
individualised treatment 219
microlaryngoscopy and biopsy 220
subglottic cancer 218
supraglottic cancer 218
symptoms 219
Laryngeal crepitus 66
Laryngeal inflammation 183
Laryngomalacia 51, 262
Laryngopharyngeal reflux 190, 190192 see also Globus pharyngeus
Larynx and trachea 28
anatomy 28, 29
nerve supply 3031
vocal folds 30
Laser-assisted uvulopalatoplasty (LAUP) 225, 225
Lateral cervical cysts (branchial cyst) 180
Lateral sinus thrombosis 100
Left recurrent laryngeal nerve 30
Leiomyosarcoma 168 see also Sinonasal tumours
Lemierre's syndrome 189
Leukotriene receptor antagonists, for nasal polyps 153
Little's area 17, 17, 18, 156
Ludwig's angina 212
Lupus pernio 165
Lymphadenitis 179, 180
Lymphovascular malformations 180, 262
Macrolide antibiotics
chronic rhinosinusitis 150
nasal polyps 153
Malignant tumours of larynx 174, 175
Malleus 5
Malleus and/or incus ossicular fixation 87
Masking 73
Mastoiditis 100
Maxillary sinusitis 47
McCormick toy test 248249
Mechanical feedback amplification 11
Mediastinitis 189
Medullary thyroid carcinoma 205
Ménière's disease 46, 86, 88, 89, 116120
attacks of vertigo 117
blood tests 117118
crisis of Tumarkin 117
endolymphatic hydrops 116
MRI scanning 118
prevention of attacks 118119
pure tone audiogram 117, 118
sensorineural hearing loss 117, 118
surgical management 119
Ménière's syndrome 116
Meniett device 119
Meningitis 100
Metastatic lymph node, as cystic neck mass 180
Microbiological tests 70
blood culture 70
fresh tissue samples 70
Micrognathia/macroglossia 262
Microscopic suction clearance, in otitis externa 95
Middle ear 2
anatomy 46, 5
embryology 2
Eustachian tube 6
facial nerve 6
ossicles 5
physiology of hearing 911, 10, 11
temporal bone 6
Midfacial segment pain 141, 142
Migrainous vertigo 89
Misting test 148
Mixed deafness 54
Modiolus 7
Multiple sclerosis 89
Muscular triangle 22, 23
Myringotomy 99
Nasal crusting 165
Nasal cycle 16
Nasal discharge see Rhinorrhoea
Nasal itching and sneezing 47
Nasal obstruction 47, 135138, 151, 161, 169
diagnostic algorithm for 79
differential diagnosis 137
examination 136, 136
nasal polyp and 136, 136 (see also Nasal polyps)
Nasal polyps 136, 147, 151154
allergy testing 152
antrochoanal polyps 138, 151
asthma and 151
bilateral 138
and cystic fibrosis in children 151, 152
differential diagnosis 152, 153
grading of 149
nasal polypectomy 154
and polypoidal inferior turbinates 153
rhinoscopy and nasal endoscopy 152
and sinonasal neoplasia 152
unilateral 138
Nasal steroid drops/sprays, for nasal polyps 152, 153
Nasal trauma 160163
clinical history and examination 160161, 161
closed reduction 162163
nasal fracture 160, 162
septal haematoma 162
Nasal vestibulitis 135
Nasendoscopy 148
Neck lump 4950, 178181
branchial cyst 180, 181
differential diagnosis 180181
fine-needle aspiration 179, 180
lump in left anterior triangle of neck 179, 179
Neck lumps, benign 211214
blood tests 212
branchial/lateral cervical cysts 213, 214
causes 211, 211
clinical examination 212
dermoid cysts 213
history examination 211212
lymphangiomatous malformations 214
paragangliomas 214
ultrasound scan with FNA cytology 212
Neck lymphadenitis 213
Necrotic lymph node 180
Necrotising fasciitis 189
Necrotising ‘malignant’ otitis externa 90
ear pain and discharge in elderly diabetic patient 9092
treatment 92
Necrotising otitis externa 94
Needle aspiration, peritonsillar abscess 188
Neurological examination 6869
corneal reflex, testing 69, 69
cranial nerve assessment 68
neurological tests 68
Newborn screening, for hearing 12
Nose, anatomy of 16, 16
blood supply 17, 1718
choanae 16
internal nasal valve 16
lateral nasal wall 1617, 17
nasal vestibule 16
Nose bleed see Epistaxis
Nose, clinical examination of 59, 61
interior of nose 61, 62
nasal lining and turbinates 63
patency of nasal airways 61, 62
Obstructive sleep apnoea (OSA) 221226
apnoea–hypopnoea index (AHI) 224
CPAP rhinitis 225
Epworth sleepiness scale (ESS) 224
history and examination 222, 222223
management options 224225, 226
multidisciplinary team approach 225
nasal continuous positive airway pressure (CPAP) 225
potential consequences 222
risk factors 222
signs associated with 223
sleep nasendoscopy 224
sleep study 224
Obstructive sleep apnoea syndrome 50
Oculomotor nerve (CN III) 33
Odynophagia 185
Oesophageal web 178
Oesophagectomy 178
Olfactory bulb 21
Olfactory loss, due to trauma 140
Olfactory nerve (CN I) 33
Olfactory neuroblastoma 167 see also Sinonasal tumours
Olfactory system 19, 20
Ophthalmic artery 18
Optic nerve (CN II) 33
Oral and pharyngeal cancers 215218
clinical presentation 216, 216, 217
investigation and diagnosis 217
lifestyle habits and risk factors 215216
multidisciplinary team approach 218
surgery/radiotherapy 218
Organ of Corti 7
OSA see Obstructive sleep apnoea (OSA)
Ossicular discontinuity 86
Osteogenesis imperfecta (van der Hoeve's syndrome) 87
Osteomyelitis of skull base 83, 84
Osteoradionecrosis of the temporal bone 91
Otalgia see Ear pain
Otic hydrocephalus 100
Otic vesicle 2
Otitis externa 9295, 230
causes 93
differential diagnosis 94
diffuse 92
localised 92
treatment 9495, 95
Otitis media with effusion 85, 234, 234238
clinical features 235, 236
grommet in tympanic membrane 237, 237
in infants 234
investigations 235, 236
management 236237
tympanosclerosis and atrophy of tympanic membrane 237, 238
Otoacoustic emissions (OAEs) 12
screeners 12
Otology, cardinal symptoms in 43, 44, 81
aural fullness and facial weakness 46
hearing loss 45
otalgia 4344
otorrhoea 4445
tinnitus 4546
vertigo 46
Otomycosis (fungal otitis externa) 83, 84
Otorrhoea (discharge) 44, 4445
diagnostic algorithm for 78
from middle ear infection 94
Otosclerosis 8487, 110113
absent stapedial reflexes 85, 111
Carhart's notch on pure tone audiometry 85, 86, 111
conductive hearing loss 85
CT scan 111
differential diagnosis 8587, 112
hearing aids, use of 112
low compliance on tympanometry 85, 86, 111
Schwartz's sign 87, 111
surgical management 87, 113, 113
Otoscope 5152, 53, 227
Outer ear 1, 23
embryology 2
physiology of hearing 9
Paediatric hearing loss 245249
age-appropriate hearing tests 247, 247249
causes 246, 246
identification of 246247
opportunistic hearing screening 246247
pre-school screening 247
targeted screening 246
universal screening 246
Paget's disease 87
Papillae 32, 36, 36
Paracusis 111
Paraganglioma 181
Paranasal sinuses 18, 19
ethmoid sinuses 18
frontal sinus 18
maxillary sinuses 18
sphenoid sinuses 19
Parapharyngeal space 25, 26
Parkinson's disease, and bilateral vocal fold palsy 201
Parosmia 140
Patterson–Kelly–Brown/Plummer–Vinson syndrome 177
Perichondritis 83
Perilymph 7
Perinatal history 50
Peristaltic waves 41
Peritonsillar abscess 48, 184 see also Tonsillitis and peritonsillar abscess
Phantosmia 140
Pharyngeal arches, structures from 2, 3
Pharyngeal pouch 25, 178, 192195
barium swallow 193, 194
diverticulectomy 194
endoscopic stapling of pouch 193, 194, 195
plain radiograph of neck and cervical spine 193
wait and watch policy 193
Pharynx 25, 28
hypopharynx 25, 28
nasopharynx 25
oropharynx 25
Phonosurgery 199, 200
Pinna 2, 4
blood supply of cartilage of 2
Pinna haematoma 132
Plasmacytoma 168 see also Sinonasal tumours
Play audiometry 248
Pneumatic otoscopy 59, 61
Polysomnography (PSG), for sleep apnoea 224
Postcricoid carcinoma 177
Postnasal drip 47
Preauricular abnormalities 2
Precancerous lesions, and hoarseness 175, 175
Bell's palsy 108
sensorineural hearing loss 126
Presbyacusis 114116
investigation 115, 115
management 115116
pure tone audiometry 115, 115
Presbycusis see Presbyacusis
Pretracheal fascia, neck 22
Pretracheal space 25, 27
Prevertebral fascia, neck 22
Prochlorperazine 119
benign paroxysmal positional vertigo 124
Progressive chronic otitis media 91
Propranolol, for lymphangiomatous malformations 214
Proton pump inhibitors
globus pharyngeus 192
vocal fold paralysis 201
Protrusion of eye 46
Pseudomonas aeruginosa 83, 93
Pure tone audiometry 7273, 73
Quinsy see Peritonsillar abscess
Radioallergosorbent test (RAST) 152
Ramsay Hunt syndrome 46, 94, 109, 109
Recurrent laryngeal nerve 30, 37, 198, 201
re-innervation of 202
Reflux oesophagitis 49
Reinke's oedema 200, 200
Respiratory papillomatosis 262, 263
Retropharyngeal abscess 262
Retropharyngeal space 25, 27
Rhabdomyosarcoma 167 see also Sinonasal tumours
Rhinitis 142146
allergic 142, 144
blood test 145
clinical features 143144
with deviated nasal septum 137
immunotherapy 146
with inferior turbinate hypertrophy 137
non-allergic 142, 143
pharmacotherapy 145146
of pregnancy 138, 140
skin-prick testing 144145
SNOT (sino-nasal outcome test) 145
Rhinology, cardinal presentations in 4647
alteration of sense of smell 48
epistaxis 4748
nasal obstruction 47
rhinorrhoea 47
Rhinorrhoea 47, 227229
Rhinosinusitis 47
with nasal polyposis 137
Rinne's tuning fork test 55, 56
false-negative 58, 59
Saline nasal douching
chronic rhinosinusitis 150
rhinitis 145
Saliva 37
Salivary gland diseases 206211
blood tests 208
causes 207
clinical features 208
CT and MRI 209
interventional sialography 209210
management 210
microbiological tests 209
parotid glands tumour 206, 206
plain radiographs 209
ultrasound-guided fine needle aspiration (FNA) 209, 209
Samter's triad 151
Sarcoidosis 163 see also Granulomatous conditions of nose and paranasal sinuses
Scarlet fever 185, 242
Scottish Bell's Palsy Study 109
Semicircular canals 78
Semont manoeuvre 124
Sensorineural deafness 54
Sensorineural hearing loss 124127
causes 125, 125
drug history 125
management 126
Rinne's test 125
Weber's test 125
Sensorineural hyposmia 139
Serosanguineous discharge 45
Severe otitis externa, and ear pain 43
Sialadenitis 180
Sialolithiasis 180
Siegle speculum, for pneumatic otoscopy 59, 61
Silver nitrate nasal cautery 158
Singer's nodules 199
Sino-Nasal Outcome Test-22 Questionnaire (SNOT- 22) 149
Sinonasal tumours 167171
cancer of maxillary antrum 169, 170
clinical features 168169
CT scan 169, 170
diplopia 168
inverted papilloma 168, 169170
juvenile angiofibroma 168169, 170
MRI 169, 170
nasopharyngeal malignancies 171
tumour subtypes 167, 168
Sinus ostia 17, 17
Sjögren's disease 37
Sleep nasendoscopy 224
Smell, physiology of 19
olfactory cells 1920
olfactory pathway 21
olfactory processes 2021
Snoring 50, 221 see also Obstructive sleep apnoea (OSA)
Sodium fluoride, in otosclerosis 112
Sore throat 48
in children 231234
Speech audiometry 248249
Speech therapy, for singer's nodules 199
Stapedectomy 87, 113
Stapedius muscle 5, 10
Stapes 5
Staphylococcus aureus 93
Stereocilia, of cochlea hair cells 11, 12
Ménière's disease 119
nasal polyps 153
sensorineural hearing loss 126
Stertor 50
Streptococcus pyogenes 185
Stridor 50
Subglottic haemangioma 262
Subglottic stenosis 262
Subglottis 28
Submandibular gland hypertrophy 180
Submandibular space 25, 26
Submandibular triangle 22, 23
Submental triangle 22, 23
Subperiosteal abscess 100
Supraglottis 28
Surgical labyrinthectomy 119
Swallowing, difficulty in see Dysphagia
Swallowing, physiology of 39
oesophageal stage 40, 41
oral stage 39, 3940
pharyngeal stage 4041
Taste, physiology of 32
taste buds 32, 36, 36, 36
taste pathways 3637
Taste receptor cells (TRCs) 32
Temporal bone 1, 6
Tensor tympani 5, 11
Throat see Pharynx
Throat, examination of 63
fibreoptic endoscopy 63, 65
headlight and tongue depressor, use of 63, 64
indirect laryngoscopy 63
Thudicum's speculum 61, 62
Thyroglossal cysts 66, 180, 242245
causes and pathogenesis 243, 243
clinical features 243244, 244
embryology of 243
modified Sistrunk's procedure 245
surgical excision 244, 245
thyroid function tests 244
ultrasound-guided fine-needle aspiration 244
ultrasound scan of neck 244
Thyroid and parathyroid glands
anatomy 31, 31
embryology 31
neurovascular supply and lymphatic drainage 32
Thyroid cancer 203 see also Thyroid swellings
management of 204205
Thyroid swellings 202206
clinical features 202203, 203
CT scan 204
fibreoptic flexible nasendoscopy 203
guided fine-needle aspiration (FNA) cytology 203, 204
referral in 204
thyroid function tests 203
thyroid nodules 202
thyroid ultrasound 203
Tinnitus 44, 4546
dull, lower frequency, continuous 45
fluctuant 46
high-frequency hissing and ringing 45
pulsatile 45
Tinnitus retraining therapy 119
Tonsillitis and peritonsillar abscess 184189
bacterial tonsillitis 184
Brodsky classification of tonsillar size 188, 188
Centor and FeverPAIN criteria 187, 187
chronic tonsillitis 186
clinical features 185, 185186, 186
glandular fever with exudates 185, 185
management 188189
peritonsillar cellulitis/abscess 186, 188
recurrent tonsillitis 186
skin rash by streptococcal sore throat 185186, 186
tonsillectomy 189
viral tonsillitis 184
Toxoplasma gondii 179
Toxoplasmosis 179
Tracheomalacia 262
Transient otoacoustic emission (TOAE) test 247
in neonates 246
Trauma to ear 129132
Battle's sign 130, 131
causes 130
clinical features 130, 131
CT scan 131, 132
external ear trauma 129130, 131132
inner ear trauma 130, 132
middle ear trauma 130, 132
pure tone audiogram 131
temporal bone fractures 129, 130, 132
Triangles of neck 22, 22
anterior triangle 22, 2223
posterior triangle 22, 23
Trigeminal nerve (CN V) 33, 40
Trochlear nerve (CN IV) 33
Tuberculosis 175
Tumour, and airway obstruction 183
Tumours of nasal cavity 137
Tuning fork tests 55
Rinne's test 55, 56
Weber's test 57, 5758, 58
Tympanic membrane 4, 5
derivation of 2, 3
light reflex 4, 5
pars flaccida 4, 5
pars tensa 4, 5
Tympanometry 10, 73, 74, 248
Tympanosclerosis 85
Tympanostomy tube 99
Ultrasound-guided FNA 72
Upper airway disorders, paediatric 261265
causes 261, 262
chest and neck radiographs 263
CT/MRI 264
examination 263264
history 261, 263
laryngotracheobronchoscopy under general anaesthesia 264
management 264265
oxygen saturation monitoring 264
Upper airway resistance syndrome (UARS) 221
UPSIT test (University of Pennsylvania Smell Identification Test) 137
Vagus nerve (CN X) 34, 40
Vascular ring 262
Vasoconstrictor nasal sprays, long-term use of 140
Vertigo 46
acute vestibular failure and 8789
causes 121
differential diagnosis 89
duration of 88
examination 8889
history taking in 44, 46
Vestibular nerve section 119
Vestibular neuritis 89
Vestibular pathway 8
Vestibular reflexes 15
vestibulo-ocular reflex 15
vestibulospinal reflexs 15
Vestibular rehabilitation exercises 88
Ménière's disease 119
Vestibular schwannomas (VS) 127, 127129
investigations and clinical findings 129
stereotactic radiation therapy 128
surgical approach 128129
Vestibular sedatives 89, 119
Vestibular system
ampullae of semicircular canals 1415, 15
utricle and saccule 14, 14
vestibular labyrinth 13
Vestibule 7
Vestibulocochlear nerve (CN VIII) 7, 34
Video endoscopic system, for evaluation of larynx 197, 197
Viral tonsillitis 233
Visual reinforcement audiometry (VRA) 248
Voice disorders and vocal fold pathology 195202
causes of 196
chest X-rays and CT scans 198
contact ulcers 200
history and assessment 196197
laryngeal evaluation 197, 197, 198
normal vocal cords 196
perceptual evaluation 198
Reinke's oedema 200, 200
thyroid function tests 198
video laryngo-stroboscopy 197, 197, 198
vocal fold nodules 199
vocal fold paralysis 201202
vocal fold polyp 199, 199200
Voice, physiology of 37
phonation 37, 38
pitch 3738
VS see Vestibular schwannomas (VS)
Wax 3
Weber's tuning fork test 57, 5758, 58
Wegener's granulomatosis see Granulomatosis with polyangiitis (GPA)
Young's syndrome 137
Zenker's diverticulum 192
Chapter Notes

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First principleschapter 1

1.1 The ear
The ear is divided anatomically into outer, middle and inner sections, with the latter two embedded in the temporal bone (Figure 1.1). The sections contain the following structures:
  • Outer ear: pinna, concha, and external auditory canal (EAC) or meatus
    zoom view
    Figure 1.1: Anatomy of the ear.
  • 2Middle ear: tympanic membrane, tympanic cavity (or middle ear space), the three ossicles (malleus, incus and stapes), two muscles (stapedius and tensor tympani), a section of the chorda tympani nerve (a branch of the facial nerve) that passes through and the superior opening of the Eustachian tube
  • Inner ear: the cochlea, vestibule and three semicircular canals
The external ear develops from six tubercles of the first branchial arch, as do the malleus, incus and tensor tympani. The stapes and stapedius (Figure 1.2) are derived from the second arch. The distal portion of the first pharyngeal pouch comes into contact with the epithelial lining of the first pharyngeal cleft, forming the EAC; the proximal portion of the first pharyngeal pouch forms the middle ear and the Eustachian (or pharyngotympanic) tube.
The tympanic membrane is formed from an ectodermal epithelial lining, an intermediate layer of mesenchyme and an endodermal lining from the first pharyngeal pouch.
The inner ear develops from the otic vesicle, an epithelial sac derived from the surface ectoderm of the neural tube.
External ear and acoustic meatus
The external ear or pinna is cartilaginous with closely adherent perichondrium (Figure 1.3). The blood supply of the cartilage of the pinna is entirely dependent on the perichondrium. The EAC is about 25 mm in length, cartilaginous in the outer one third and bony in the inner two thirds.
3Wax is made up of secretions produced from specialised sweat glands in the EAC called ceruminous glands, and skin cells. Skin and wax usually migrate radially outward from the tympanic membrane and then laterally along the EAC.
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Figure 1.2: (a) Derivation of the tympanic membrane and (b) structures derived from the pharyngeal arches.
4Tympanic membrane
The tympanic membrane (eardrum) is composed of three layers (skin, fibrous tissue and mucosa), in keeping with its embryological origin. The normal appearance is pearly and opaque and its slight concavity results in the ‘light reflex’ (Figure 1.4), a characteristic triangular cone of light seen when light is reflected from its surface.
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Figure 1.3: The pinna.
The pars tensa is the larger inferior section of the membrane and has a well-organised fibrous (middle) layer and an annulus or thickened ring at the periphery. In the smaller superior portion, the pars flaccida, the fibrous middle layer is poorly organised and the annulus is incomplete superiorly.
Middle ear
The middle ear (Figure 1.5) is an air-containing space, and developmentally a continuation of the Eustachian tube. 5It contains three small middle ear bones called ossicles – the malleus, incus and stapes. The tensor tympani attaches the malleus to cartilage of the Eustachian tube and dampens background sounds such as chewing. The 1 mm long stapedius muscle attaches the neck of the stapes to the pyramidal eminence of the posterior middle ear wall and prevents loud sounds causing acoustic trauma.
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Figure 1.4: Left tympanic membrane. F, pars flaccida; H, handle of malleus; L, light reflex; T, pars tensa.
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Figure 1.5: Middle ear anatomy.
It also functions reflexively to 6dampen background low frequency sound such as the sound of one's own voice. The round and oval windows, lateral semicircular canal, basal turn of the cochlea and tympanic plexus of nerves are closely related to the medial aspect of the middle ear.
Temporal bone The pneumatised (air-filled) mastoid cells in the temporal bone are connected to the middle ear through the aditus. This reservoir of air helps prevent wide fluctuations of middle ear pressure. Chronic middle ear disease reduces the pneumatisation, causing a sclerotic (dense) mastoid.
Facial nerve The facial nerve has a long and tortuous course through the temporal bone, exiting through the stylomastoid foramen in front of the mastoid process (see p. for more on anatomy of the facial nerve).
The facial nerve controls the motor activity of most facial muscles, and it has intimate association with the middle and inner ear after it courses through the internal auditory canal in the petrous part of the temporal bone. It also contains sensory afferents, including the chorda tympani, which carries taste fibres from the anterior two thirds of the tongue. The facial nerve is posterosuperior to the medial wall of the middle ear.
Eustachian tube The Eustachian tube extends from the anterior wall of the middle ear to the lateral wall of the nasopharynx. About one third of the tube proximal to the middle ear is bony; the rest is composed of cartilage. At the lateral aspect of the nasopharynx is a raised mucosal elevation, the torus tubarius formed by underlying cartilage, which opens into the nasopharynx. The tube is shorter, wider and more horizontal in children, making them more prone to middle ear infections than adults. The opening of the tube during swallowing, with the action of the muscles of the palate, allows aeration of the middle ear and the equalising of pressures either side of the tympanic membrane.
7Inner ear
The inner ear consists of:
  • The vestibule and semicircular canals, responsible for balance
  • The cochlea, responsible for hearing
They lie within a bony labyrinth (network of canals), which is one of the densest bones in the body and protects the closely adjacent membranous labyrinth and its sensitive neuroepithelium. The membranous labyrinth is hollow and filled with endolymph, a fluid with similar ionic concentrations to intracellular fluid. Perilymph, surrounding the membranous labyrinth, is a filtrate of blood and cerebrospinal fluid (CSF) and is similar to extracellular fluid. The endolymph transmits vibrations to the membranes via electromechanically sensitive cells called hair cells which generate action potentials subsequently transmitted to the vestibulocochlear nerve (cranial nerve VIII).
Vestibule This is the ‘entrance’ to the inner ear, via its oval window on the lateral (tympanic) wall, and measures 5 × 5 × 3 mm. It sits behind the cochlea and in front of the semicircular canals and consists of two membranous sacs: the saccule and the utricle. It contains receptors that sense gravity and acceleration.
Cochlea The snail-shaped cochlea is a system of three tubes coiled 2.5 turns and a bony core called the modiolus. It contains the cochlear duct of the membranous labyrinth, which has a pair of perilymph filled chambers, the scala vestibuli and the scala tympani either side (Figure 1.6). Inside the cochlear duct, in a structure known as the organ of Corti, there are nearly 20,000 hair cells, each connecting to its own nerve receptor. These are stimulated by endolymph movement generated by the footplate of the stapes at the oval window. The movement of endolymph is sensed by the stereocilia of the inner and outer hair cells.
Semicircular canals The three semicircular canals (superior, posterior and lateral) are at right angles to each other. Each canal has a widening called the ampulla which contains the embedded 8neuroepithelial hair cells. Rotatory motion, linear acceleration and deceleration result in movement of the surrounding endolymph and corresponding movement of the hair cells – the vestibular inputs are integrated with proprioceptive and visual inputs in the brainstem to maintain balance.
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Figure 1.6: Cross section of the cochlea.
Auditory pathway The auditory pathway is responsible for hearing and extends from the cochlea to the cortex, with processing occurring at each stage:
  • Cochlear (or auditory) nerve
  • Cochlear nuclei of the pons and medulla oblongata
  • Superior olivary nucleus of the brainstem (mostly pontine)
  • Inferior colliculus of the midbrain
  • Medial geniculate nucleus of the thalamus
  • Auditory cortex of the temporal lobe
Vestibular pathway The vestibular pathway is responsible for balance and co-ordinates the perception of movement with changes in postural muscle tone (see ‘Physiology of balance’, p. ):
  • 9Vestibular nerve
  • Four vestibular nuclei of medulla (and pons)
  • Branches to the eye muscle nuclei:
    • CN III (oculomotor nerve innervating medial rectus)
    • CN VI (abducens nerve innervating lateral rectus)
  • Branches to the vestibulospinal tract (head and trunk movement co-ordination)
  • Branches to the cerebellum
Physiology of hearing
Sound is a mechanical vibration which sets up oscillations of air molecules. The ear is structured to collect, amplify and transduce this mechanical energy into action potentials. Signals generated in the cochlea travel to the cochlear nuclei of the brainstem via the auditory nerve; from the nuclei they branch to the thalamus and then on to the auditory cortex of the temporal lobes.
Outer ear
The external ear acts as a ‘collecting device’ for these vibrations and propagates the sound towards the tympanic membrane. The conchae and the EAC act as acoustic resonators, affecting the sound pressure at the tympanic membrane. The EAC contributes substantially to an increase in sound pressure level at the tympanic membrane. Pressure changes in the EAC vibrate the tympanic membrane, which in turn causes movement of the ossicular chain in the middle ear.
Middle ear
The middle ear is both a coupler (transferring sound from air to fluid media) and a transformer (the three ossicles increase the sound energy transmitted to the cochlea to a greater extent than would occur from a direct coupling). The movement of the tympanic membrane results in a focused application of force by the ossicular chain at the oval window.
The piston-like vibration of the stapes in the oval window leads to a pressure differential between the scala vestibuli and the scala tympani, which is essential to the mechanical excitation of the cochlear hair cells. The transformer effect of the middle ear is primarily due to:
  • 10The area of the tympanic membrane being greater than the area of the stapes footplate (Figure 1.7), such that pressure at the footplate is in effect 14 times higher than the pressure on the tympanic membrane
  • A lever system (Figure 1.8), whereby the displacement of the incus is less than that of the malleus as the distance of the long process of the incus is shorter than the manubrium of the malleus from the fulcrum. This results in the incus a applying greater force than the malleus in the ratio 1.3:1.0
The acoustic reflex Stapedius has a protective role by reducing the intensity of sound signals reaching the inner ear; this is called the acoustic (or attenuation) reflex. When high intensity sound is transmitted to the cochlear nuclei of the brainstem, interneurons to the pontine motor nuclei of the facial nerve initiate a reflex after just 40–80 ms. The stapedius muscle (the effector organ of the reflex arc, innervated by the facial nerve), contracts to pull the stapes away from the oval window of the cochlea.
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Figure 1.7: The ratio of the area of the tympanic membrane and stapes footplate (T/S) results in an increase in pressure at the oval window.
11The overall effect of the acoustic reflex is to make the ossicular chain rigid, thereby attenuating transmission of lower frequency sound by up to 40 dB. Sounds of long duration are suppressed at high levels, whereas short duration bursts of sound energy are transmitted relatively unimpeded by middle ear muscle activity. This attenuation is also initiated pre-emptively, such as just before speaking.
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Figure 1.8: Unequal displacements of the malleus (L1) and incus (L2) result in a pressure increase.
The physiology of the human tensor tympani remains obscure. In contrast to findings in most animals, it does not respond to sound unless the sound is strong, sudden and causes a ‘startle’ response. It acts by tightening the ear drum by pulling the manubrium of the malleus inwards.
Inner ear
Displacement of perilymph within the scala vestibuli by the motion of the stapes imparts a travelling wave of vibration to the basilar membrane (Figure 1.9) of the cochlear duct. The travelling wave builds up to a maximum depending on the pitch, and then falls to nothing. The wave peaks near the base of the cochlea for high-pitched sounds (where it is stiffer), and near the apex for low-pitched sounds. The fluid wave causes a shearing force on the stereocilia of the hair cells that bends them and induces a receptor potential (Figure 1.9). This causes the release of neurotransmitters. There are two types of hair cell:
  • Inner hair cells are responsible for the majority of the acoustic nerve signal
  • Outer hair cells amplify sound-induced vibrations by vibrating at the frequency of the acoustic signal (known as mechanical feedback amplification)
12Neurotransmitters released at the base of the hair cell generate excitatory postsynaptic potentials (EPSPs) in primary afferent nerve fibres of the auditory nerve. All-or-nothing responses propagate through these axons to second order fibres in the brainstem. About one fifth of a second after detection, electrical signals reach the auditory cortex of the temporal lobes and sounds are perceived.
zoom view
Figure 1.9: Stereocilia of cochlea hair cells. Displacement towards the tallest row of stereocilia is depolarising. Differences in receptor potential in each state are shown in blue below the cells.
Cells in the central auditory system are exquisitely sensitive to small differences in intensity and time differences of the sound arriving at both ears, giving rise to the ability to localise sound.
13Physiology of balance
Balance is maintained by co-ordination of information from three main sensory systems (Figure 1.10):
  • The vestibular system
  • The eyes
  • Proprioception, i.e. sensory information from muscles, joints, tendons and ligaments
The signals from these systems are integrated in the brainstem, cerebellum and cortex. Disorders affecting any of these structures or their physiology (e.g. cardiac, respiratory, metabolic diseases) can affect balance.
Vestibular system
Vestibular labyrinth In the inner ear the vestibular labyrinth detects acceleration of the head in any direction, whether in a straight line (linear) or turning (angular). Similar to the cochlear system of sensing hearing, the mechanical stimuli are transduced into electrical impulses which travel along the vestibular nerve to the brainstem.
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Figure 1.10: Overview of the balance system.
14Utricle and saccule These are called the otolithic organs: they contain crystals surrounded by less dense endolymph. The difference in flow response of the crystals and endolymph is sensed by hair cells during linear acceleration (Figure 1.11), such as side-to-side or up-and-down movement. When the head is tilted from side to side, gravity will cause a shearing force between the otolithic membrane and the surface of the maculae, resulting in a bending of the stereocilia.
The deflection of the stereocilia in the direction of the longer stereocilia causes the transduction channels to open, allowing hair cell depolarisation. Conversely, movement of the stereocilia in the opposite direction causes hyperpolarisation. The hair cells then generate vestibular nerve action potentials, which sends information about head position to the brainstem and spinal cord. This is relayed to eye muscles (utricle) and posture muscles (saccule).
Ampullae of the semicircular canals These detect angular acceleration, for example the movement experienced on a merry-go-round (Figure 1.12). The ampulla contains the saddle-shaped crista, on which the hair cells sit. The stereocilia of the hair cells protrude into a gelatinous material called the cupula.
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Figure 1.11: The utricular macula, demonstrating the effect of bending forward.
With a turn of the head, the inertia of the endolymph in the semicircular canal causes the cupula to move, deflecting the stereocilia and stimulating transduction. Each semicircular 15canal is paired with another in a parallel plane on the opposite side of the head. One gives an excitatory response and the other an inhibitory response in a given plane.
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Figure 1.12: The ampulla of the lateral semicircular canal, demonstrating the effect of rotation.
Vestibular reflexes The vestibular system is involved in two reflexes:
  • The vestibulo-ocular reflex co-ordinates and stabilises eye movement with head movement, so that objects can remain in focus and in fixed view. The interneurons are between the vestibular nuclei and the oculomotor and abducens nuclei
  • The vestibulospinal reflexes co-ordinate head and body movement with posture. The interneurons are between the vestibular nuclei and the vestibulospinal tract of the spinal cord, where they synapse with efferents to neck and posture muscles
161.2 The nose and paranasal sinuses
The external nose consists of a bony and mainly cartilaginous skeleton (Figure 1.13). The two nasal cavities are separated by a bony and cartilaginous septum and terminate at the posterior choanae (from the Greek word for funnel), which lead to the nasopharynx.
The nasal vestibule is the most anterior part of the nose. Each is formed by nasal cartilages, connective tissue and hair-bearing skin. The main cartilages are the bilateral greater alar cartilages (lower lateral cartilages) and the cartilaginous nasal septum.
The junction between the nasal vestibule and the nasal cavity is the narrowest part of the nasal airway, known as the internal nasal valve.
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Figure 1.13: Cartilaginous skeleton of the nose.
Lateral nasal wall On the lateral wall of the nose are three turbinates (inferior, middle and superior) or bony ridges 17which increase the surface area of the nasal mucosa; they have a rich nerve and blood supply, and are therefore sensate. The ostia (openings) of the sinuses, apart from the sphenoid sinus and the opening of the nasolacrimal duct, are located on the lateral wall of the nose in the meatus that lie inferior to the turbinates (Table 1.1).
Blood supply The nose receives blood from both the internal and external carotid arteries. There is a rich vascular anastomosis between vessels from the two systems: for example, in Little's area, an anteroinferior part of the nasal septum, four arteries meet to form Kiesselbach's plexus (Figure 1.14).
Table 1.1   Sinus ostia openings into lateral wall of nose
Sinus ostia
Opening of posterior ethmoidal sinus
All open into hiatus semilunaris:
  • Anterior ethmoidal sinuses
  • Frontal sinus through frontonasal recess
  • Maxillary sinus
Opening of nasolacrimal duct
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Figure 1.14: Blood supply of the medial wall of the nose.
18The internal carotid branches supplying the nose are the:
  • Anterior ethmoidal artery
  • Posterior ethmoidal artery
The ethmoidal arteries are branches of the ophthalmic artery. They descend into the nasal cavity through the cribriform plate.
The external carotid branches supplying the nose are the:
  • Sphenopalatine artery
  • Greater palatine artery
  • Superior labial artery
  • Lateral nasal arteries
Paranasal sinuses
The paranasal sinuses (Figure 1.15) are divided into groups named according to the bones in which they lie:
Maxillary sinuses (or antra) These are the largest of the paranasal sinuses and are located in the maxillary bones. The superior wall is the floor of the orbit, the sinus floor is formed by the alveolar process of the maxilla and can sometimes be perforated by the apices of the molar teeth. This sinus can be involved in orbital blowout fracture and root canal and dental infections.
Frontal sinus This is in the frontal bone, superior to the eyes, and forms the roof of the orbit; its posterior wall is the bony anterior cranial fossa.
Ethmoid sinuses These are formed from several discrete air cells within the ethmoid bone between the nose and the eyes. They are further divided according to their drainage into anterior and posterior groups (Table 1.1). The lateral wall forms the (paper-thin) lamina papyracea, which separates the sinus from the orbital cavity. Ethmoidal infection, especially in children but also in adults, can breach the lamina and involve the orbit, with the potential to affect vision by compressing the orbital contents.
19Sphenoid sinuses These are in the sphenoid bone at the centre of the skull base under the pituitary gland. The lateral walls are related to vital structures, including the internal carotid artery, cavernous sinus and cranial nerves II–IV. The transnasal approach to the pituitary gland is through the sphenoid sinuses.
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Figure 1.15: Paranasal sinuses. Frontal sinus (FS); ethmoid sinuses (ES); uncinate process (UP); inferior turbinate (IT); concha bullosa (CB); maxillary sinus (MS).
Physiology of smell
The olfactory system (Figure 1.16) allows distinction between large numbers of different smells.
Olfactory cells
The olfactory area is a region of specialised sensory epithelium in the roof of the nasal cavity, with a surface area of 20200–400 mm2. This area is increased by receptor cells’ cilia, which project into the mucus lining of the nasal epithelium. Other types of cells of the olfactory epithelium include columnar supporting cells and basal cells. The basal cells continually divide to produce new olfactory receptor cells which, because of their short lifespan, need to be continually replaced. This is an unusual characteristic, because most other nerve cells cannot be regenerated.
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Figure 1.16: The olfactory system; (a) central pathways, (b) olfactory bulb detail.
Olfactory processes
The process of sniffing ensures maximum exposure of odours to the olfactory area, via turbulent airflow. Odours that reach this area are absorbed into the water fraction of the mucus and in turn react with the lipid bilayer of the receptor cells 21at specific sites. This causes K+ and Cl to flow out leading to depolarisation of the sensory cells. A slow compound action potential (i.e. the sum action potential of the multiple primary afferents) is generated from the olfactory mucosa. Depending on the chemical nature of the stimulus, the threshold varies: the threshold for perceiving a smell is lower than that required to identify a smell. There is also marked adaptation of the olfactory response, with an increase in threshold following exposure, but recovery occurs quickly.
Olfactory pathway
Each receptor cell is connected by non-myelinated nerve fibres to the olfactory glomeruli of the olfactory bulb. Each glomerulus receives about 25,000 fibres and fires in an ‘all-or-nothing’ fashion into the mitral or tufted cells of the olfactory bulb. These bulbar cells have (approximately 100,000 axons projecting along the olfactory tract [as the olfactory nerve (CN I)] to synapse at five cerebral regions:
  • Piriform cortex
  • Periamygdaloid area
  • Olfactory tubercle
  • Amygdala
  • Entorhinal cortex
Unlike other sensory pathways to the cerebral cortex, the olfactory pathway does not relay to the thalamus. However, fibres do leave the olfactory cortical areas and relay in the thalamus on their way to the hypothalamus or other areas, where they perhaps play a role in the regulation of the intake of food and other behaviours that depend on olfactory information.
1.3 Head and neck
Knowledge of gross and microanatomy of the head and neck is key to understanding the normal physiology of taste, phonation and swallowing. Structures located in or passing through the neck include the jugular veins, vagus nerve and carotid arteries, part of the oesophagus, the larynx and vocal cords, seven cervical vertebrae and enclosed spinal cord, along with 22sternocleidomastoid and hyoid muscles anteriorly and trapezius and other nuchal muscles posteriorly.
The neck contains various layers of fascia that divide it into different compartments:
  • Investing fascia is the outermost layer just deep to the platysma
  • Prevertebral fascia is in front of the prevertebral muscles
  • Pretracheal fascia encloses the thyroid gland and allows gliding movement during swallowing
  • The carotid sheath envelopes the common carotid artery, internal jugular vein and vagus nerve
The neck is anatomically divided into anterior and posterior triangles and extends from the skull base above to the upper border of the sternum below.
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Figure 1.17: Triangles of the neck (outlined in colour).
Anterior triangle of the neck
The boundaries of the anterior triangle (Figure 1.17) are:
  • 23Medial: midline of the neck from the chin to the manubrium sterni
  • Lateral: anterior border of the sternocleidomastoid (as described by anatomists although surgeons clinically use the posterior border of sternocleidomastoid muscle)
  • Superior: the lower border of the body of the mandible
The anterior neck is subdivided into four smaller triangles by the digastric muscle above and the superior belly of the omohyoid below. These four smaller triangles contain the following structures:
  • The muscular triangle: the anterior neck muscles, larynx, thyroid, trachea and oesophagus
  • The carotid triangle: the carotid sheath
  • The submandibular triangle or digastric triangle: the submandibular gland, facial artery and vein, hypoglossal nerve, hypoglossus, mylohyoid muscle and nerve and glossopharyngeal nerve
  • The submental triangle: the submental lymph nodes and anterior jugular vein
Posterior triangle of the neck
The posterior triangle contains the accessory nerve, the inferior belly of the omohyoid, the occipital artery, the external jugular vein, the lymph nodes and the cutaneous branch of the cervical plexus.
The floor is formed by the prevertebral fascia overlying the prevertebral muscles. Its boundaries are:
  • Anterior: posterior border of the sternocleidomastoid muscle
  • Posterior: anterior edge of the trapezius muscle
  • Inferior: the middle third of the clavicle
Anatomical levels of the neck
The anatomical landmarks of the triangles are subdivided into levels I–VI for oncological purposes (known as the Memorial Sloan–Kettering group). These are listed in Table 1.2 and shown in Figure 1.18.24
Table 1.2   Anatomical levels of the neck
Submental (between anterior belly of digastric and neck midline)
Submandibular (bounded by anterior and posterior belly of digastric)
Between skull base and hyoid: below posterior belly of digastric (IIa); posterior to spinal accessory nerve (IIb)
Level of carotid bifurcation and omohyoid
Between omohyoid and clavicle
Posterior triangle – between posterior border of sternocleidomastoid and anterior boundary of trapezius
Anterior central compartment
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Figure 1.18: Anatomical levels of the neck.
25Neck spaces and applied anatomy
There are five clinically distinct potential neck spaces:
  • parapharyngeal space
  • submandibular space
  • carotid sheath space
  • pretracheal space
  • retropharyngeal space
Their anatomical boundaries and infections within them are outlined in Table 1.3.
Pharynx and oral cavity
The pharynx, or throat, is the passageway leading from the mouth and nose to the oesophagus and larynx. It is subdivided into three regions:
  • nasopharynx
  • oropharynx
  • hypopharynx
The boundaries and relationships of the pharynx and oral cavity are shown in Figure 1.19.
This is bound superiorly by the skull base and inferiorly by an imaginary line level with the soft palate. Anteriorly are the posterior choanae and laterally the Eustachian tube openings. The posterior nasopharynx contains pharyngeal mucosa and, in children, adenoid tissue.
This extends from the level of the soft palate to the base of the vallecula, i.e. the level of the hyoid bone. It contains the palatine tonsils bilaterally.
Hypopharynx (laryngopharynx)
This extends from the base of the vallecula to the inferior edge of the cricoid cartilage.26
Table 1.3   Neck spaces and infection.
Description and boundaries
Source of infection in space
Clinical features of infection
Inverted pyramidal space formed above by skull base and petrous temporal bone, with inferior apex at hyoid bone
Tonsils (quinsy), pharynx, teeth or salivary glands
  • Medial displacement of lateral pharyngeal wall
  • Potential airway obstruction
  • Trismus (inability to open mouth)
  • Dysphagia (difficulty swallowing)
  • Retromandibular fullness
Septic thrombosis of internal jugular vein and airway obstruction
In continuity with floor of mouth, along posterior edge of mylohyoid
Usually dental
Presenting features of infection or cellulitis (Ludwig's angina) are:
  • Odynophagia (painful swallowing)
  • Feeling of being strangled
  • Stridor and dyspnoea in severe cases
Spread of infection via fascial planes, leading to swelling and posterior and superior displacement of tongue, causing airway compromise (a surgical emergency requiring drainage of abscess and securing of airway)27
Carotid sheath
Area between fascial layers surrounding neurovascular bundle [carotid artery, internal jugular vein, vagus nerve, ansa cervicalis (nerve loop supplying infrahyoid muscles)]
Usually from parapharyngeal or submandibular space
Painful torticollis (stiff, usually laterally flexed, neck)
Life-threatening infectious complications, e.g. septic shock, endocarditis and cavernous sinus thrombosis
Space around trachea, containing pharynx, trachea, thyroid gland and oesophagus
Tonsils, trachea, oesophagus, or thyroid, or blunt laryngeal trauma
  • Odynophagia
  • Hoarseness
  • Emphysema (some patients)
Spread of infection to mediastinum, mediastinal emphysema, and laryngeal oedema
Behind pharynx and oesophagus. Contains lymph nodes (max number in children < 4 years old)
Acute respiratory infections
  • Odynophagia
  • Drooling
  • Cervical rigidity
  • ‘Hot potato’ voice (speaking as if has mouthful of hot food)
Pharyngeal swelling and abscess, with potential spread to mediastinum, airway obstruction and rupture of abscess causing aspiration pneumonia
It has subdivisions of the 28posterior pharyngeal wall, post-cricoid region and pyriform fossae.
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Figure 1.19: Regions of the pharynx.
Larynx and trachea
The larynx or ‘voice box’ has a cartilaginous skeleton consisting of three single (thyroid, cricoid and epiglottic) and three paired (arytenoid, corniculate and cuneiform) cartilages (Figure 1.20). The larynx extends vertically from the tip of the epiglottis to the inferior border of the cricoid cartilage – the only complete cartilaginous ring above the trachea. Its interior can be divided into the:
  • Supraglottis: consisting of the whole epiglottis, aryepiglottic folds, vestibular folds, ventricles and arytenoids
  • Glottis: the vocal folds and the area 1 cm inferior to them (Figure 1.21)
  • Subglottis: below the glottis to the lower border of the cricoid cartilage
Functionally, the larynx is essential in breathing, phonation and protecting the airways against aspiration.29
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Figure 1.20: Vocal fold and laryngeal anatomy. (a) Endoscopic view of the larynx from above with the vocal folds in abduction (opened position). The trachea and subglottis are visualised through the rima glottidis. (b) Vertical cross-section through the larynx showing the false vocal folds, true vocal folds and the ventricles. A, arytenoid cartilage; E, epiglottis; F, false vocal fold; P, pyriform fossa; *, true vocal fold; R, right side; S, subglottis; T, trachea; V, ventricle.
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Figure 1.21: Open and closed view of the glottis (coronal view).
30Vocal folds
The vocal folds (or cords) are adapted for phonation. They the only part of the larynx lined (superiorly) by stratified squamous epithelium; the rest of the respiratory tract is lined by pseudostratified ciliated columnar epithelium. It is the thinner stratified squamous epithelium that makes the glottis an efficient vibratory organ. The layered anatomy of the vocal folds is crucial to the physiology of phonation (see p. ). The epithelial layer vibrates or glides over a loose layer of superficial lamina propria (Reinke's space) supported by a firm body (vocalis/thyroarytenoid muscle).
Nerve supply
The internal branch of the superior laryngeal nerve supplies sensory innervation to the glottis and larynx above this level. The external branch of the superior laryngeal nerve is motor and supplies the cricothyroid muscle. The bilateral recurrent laryngeal nerves supply sensory innervation to the subglottis and motor innervation to the rest of the pairs of intrinsic muscles of the larynx:
  • Posterior cricoarytenoids (the only abductors)
  • Lateral cricoarytenoids
  • Transverse arytenoids
  • Thyroarytenoids
The course of each recurrent laryngeal nerve is long: the left recurrent laryngeal nerve loops around the aortic arch and travels in the tracheo-oesophageal groove; the right recurrent laryngeal nerve passes under the right subclavian artery and then 31upwards into the tracheo-oesophageal groove. Both enter the larynx at the inferior cornu of the thyroid cartilage.
Thyroid and parathyroid glands
The thyroid gland (Figure 1.22) is a butterfly-shaped bilobed gland with a strand of thyroid tissue connecting the lobes called the isthmus. The gland is surrounded by its own capsule and pretracheal fascia. Between the two layers of the capsule or just outside the posterior side of the lobes are the superior (arising from the fourth pharyngeal pouch) and inferior (arising from the third pharyngeal pouch) parathyroid glands. The firm attachment of the thyroid gland to the underlying pretracheal fascia means that it moves during swallowing.
Embryology The thyroid gland descends from the foramen caecum in the tongue base to its final position in front of the trachea. The thyroglossal duct normally involutes completely, however a thyroglossal cyst (see section 7.4) can develop anywhere along the duct, most commonly below the hyoid bone in the midline.
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Figure 1.22: Thyroid and parathyroid glands.
32Neurovascular supply and lymphatic drainage The thyroid is supplied by the superior thyroid artery, a branch of the external carotid artery; the inferior thyroid artery, a branch of the thyrocervical trunk and in less than 10% of the population the thyroid ima artery, a branching directly from the brachiocephalic trunk. The recurrent laryngeal nerve and the inferior thyroid artery are closely related to the inferior pole of the gland and meticulous and careful dissection is required to avoid injury to the nerve during thyroid surgery. Lymphatic drainage frequently passes to the lateral deep cervical lymph nodes and the pre- and paratracheal lymph nodes.
Cranial nerves
The ear, nose and throat are innervated by cranial nerves (Table 1.4). Assessing these nerves’ function is a key aspect of clinical examination.
Physiology of taste
There are five primary submodalities of taste: sweet, sour, salty, bitter and umami. The tip of the tongue is the most sensitive to sweetness and saltiness. The lateral aspects of the tongue are most sensitive to sourness, and the back of the tongue is most sensitive to bitterness. Umami is sensed throughout.
Taste buds
The taste buds are situated predominantly on raised tongue protrusions called papillae (Figure 1.23), of which there are four types, as described in Table 1.5.
There are also taste buds on the palate and lips. Taste buds are a collection of 50 to 100 elongated epithelial cells called taste receptor cells (TRCs) embedded in the papillary epithelium. They are of epithelial origin and undergo constant renewal. There are three types of cells in taste buds:
  • Type I TRCs have tall microvilli and are thought to be support cells (i.e. glial-like)
  • Type II TRCs have short microvilli and sense sweet, bitter and umami tastes
  • Type III TRCs have a single thick microvillus and synapse with the adjacent gustatory nerve33
Table 1.4   Cranial nerves: origin, nuclei, foramina and function.
Sensory, motor or both
Purely sensory
Anterior olfactory nucleus
Cribriform plate
Sensory: smell
Purely sensory
Ganglion cells of retina
Optic canal
Sensory: sight
Mainly motor
Anterior aspect of midbrain
Oculomotor nucleus, Edinger–Westphal nucleus
Superior orbital fissure
Motor: levator palpebrae superioris, all extraocular muscles (except superior oblique and lateral rectus), ciliary body and sphincter papillae
Mainly motor
Dorsal aspect of midbrain
Trochlear nucleus
Superior orbital fissure
Motor: superior oblique muscle
Ophthalmic – V1
Maxillary – V2
Mandibular – V3
Both sensory and motor
Trigeminal nuclei: principal sensory, spinal, mesencephalic and motor
Superior orbital fissure – V1
Foramen rotundum – V2
Foramen ovale – V3
Motor: muscles of mastication
Sensory: face (largest cranial nerve)
Mainly motor
Posterior margin of pons
Abducens nucleus
Superior orbital fissure
Motor: lateral rectus (longest intracranial course)34
Both sensory and motor
Pons (cerebellopontine angle) above olive
Facial nucleus, solitary nucleus, superior salivary nucleus
Enters the internal acoustic canal and exits through stylomastoid foramen
Motor: muscles of facial expression, posterior belly of digastricus muscle, stapedius
Secretomotor: salivary glands (except parotid) and lacrimal glands
Sensory: taste from the anterior two thirds of tongue
Mostly sensory
Lateral to CN VII (cerebellopontine angle)
Vestibular nuclei, cochlear nuclei
Internal acoustic canal
Sensory: sound (cochlear), rotation and gravity (vestibular)
Both sensory and motor
Nucleus ambiguus, inferior salivary nucleus, solitary nucleus
Jugular foramen
Motor: stylopharyngeus
Secretomotor: parotid gland
Sensory: taste from the posterior third of the tongue
Both sensory and motor
Posterolateral sulcus of medulla
Nucleus ambiguus, dorsal motor vagal nucleus, solitary nucleus
Jugular foramen
Sensory: EAC and posterior auricle; taste from epiglottis
Motor: most laryngeal and all pharyngeal muscles (except stylopharyngeus)
Parasympathetic to nearly all thoracic and abdominal viscera35
Accessory nerve
Mainly motor
Cranial and spinal roots
Nucleus ambiguus, spinal accessory nucleus
Jugular foramen
Motor: sternocleidomastoid and trapezius muscles
Hypoglossal nerve
Mainly motor
Hypoglossal nucleus
Hypoglossal canal
Motor: tongue (except for palatoglossus [X])
CN, cranial nerve; EAC, external auditory canal
36From each cell type, processes extend up into the pore region of the bud, and nerves enter and leave the taste bud through its base.
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Figure 1.23: The tongue contains outward protrusions called papillae, of which there are three main types. Taste buds are situated in various locations on the papillae.
Table 1.5   Types of papillae
Type of papillae
Site and description
Anterior tip and sides of tongue. ‘Mushroom-shaped’
Base of tongue
Back of tongue, in close proximity to gustatory gland ducts. Shaped to collect lipase-containing secretions. Usually only 10–14 in total
Long keratinised papillae without taste buds
Taste pathways
Taste stimuli are transmitted to the brainstem via two embryologically separate pathways:
  • the chorda tympani nerve, a sensory branch of the facial nerve (VII) which runs in close proximity to the annulus of the tympanic membrane, then traverses the middle ear between the incus and malleus and joins the lingual nerve to supply the anterior two thirds of the tongue
  • 37the glossopharyngeal nerve (IX) supplies the posterior one third of the tongue
Physiology of voice (phonation)
Voice production requires:
  • An air source (the lungs)
  • A vibratory source (the vocal folds)
  • A resonating chamber (the pharynx, oral cavity and nose)
Any disorder of these components can contribute to changes in the voice.
Phonation In order to phonate, the recurrent laryngeal nerves set the vocal folds into the adducted position. However, as the vocal processes of the arytenoid cartilages (forming the posterior one third) are more bulky than the membranous vocal folds, a slight gap exists between the vocal folds. The lungs then expel air, and this airstream passes through the gap. According to the Bernoulli principle, (Figure 1.24) there is a drop in pressure at the site of the glottis and this causes the mucosa of the vocal folds to be drawn into the gap and block it. Subsequently, the sub-glottic pressure rises and causes another stream of air to pass through the glottis, followed again by a drop in pressure and glottic closure. Repeated cycles of this process set up a vibratory pattern in the vocal folds, and the resulting sound is what we interpret as voice. As the sound passes through the resonating chamber of the pharynx and oral cavity containing the palate, tongue, teeth and lips, this voice is further modulated into speech.
Pitch The tension and length of the vocal folds together with the tracheal air pressure are important in determining the pitch of the voice. Vocal fold length is altered by the cricothyroid 38and thyroarytenoid muscles. Shortening of the vocal folds leads to the tension being readjusted by the vocalis muscle. An increase in tension with maintenance of vocal fold length, as with raising the voice, leads to a rise in pitch. An increase in volume is attained by a rise of air pressure associated with a reduction in the elasticity of the glottis.
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Figure 1.24: Physiology of phonation.
39Physiology of swallowing
Swallowing is the mechanism that transmits liquids or solids from the mouth to the stomach, via the pharynx and oesophagus, without entering the respiratory tract. Although it is initiated voluntarily there are involuntary components, with complex neuromuscular involvement. Swallowing has three stages:
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Figure 1.25: Oropharyngeal phases of swallowing. (a) With a food bolus in the mouth, the airway is open and upper oesophageal sphincter closed. (b) Behind the bolus the tongue blocks the mouth and the soft palate closes the nasopharynx to block the airway. The epiglottis blocks the larynx, and the upper oesophagal sphincter opens. (c) Pharyngeal muscles contract and the bolus passes into the oesophagus. The upper oesophageal sphincter then closes.
Oral stage
This begins when fluid or food is placed into the mouth. As well as closure of the lips it requires closure of the oropharyngeal 40sphincter so that material is retained in the mouth until ready to progress into the pharynx. Solids require preparation to form a bolus, with coordinated action from the lips and buccal, mandibular and tongue movements for chewing to break up the particles and mix them with saliva. The cranial nerves involved are:
  • CN V (trigeminal nerve): sensation and mastication
  • CN VII (facial nerve): lip and buccal movements
  • CN X (vagus nerve): oropharyngeal sphincter)
  • CN XII (hypoglossal nerve): tongue movements
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Figure 1.26: Oesophageal phases of swallowing. Contraction of circular muscles pushes the food bolus down; contraction of longitudinal muscles shortens the oesophagus ahead of food.
The bolus is assembled between the tongue and the hard palate. Co-ordinated contraction of the tongue, in an anterior to posterior direction, propels the bolus posteriorly into the oropharynx with relaxation of the palatoglossal sphincter. The soft palate is pulled posterosuperiorly to close the nasopharynx to stop respiration and prevent nasal regurgitation.
Pharyngeal stage
This is completed within 1 second and involves the tongue base acting as a piston, pumping the bolus towards the entrance of 41the oesophagus, as well as the elevation of the larynx by the suprahyoid muscles. This gives rise to a negative pressure in the entrance of the oesophagus. There is associated relaxation of the upper oesophageal sphincter, allowing the bolus into the oesophagus. Movement of the leading edge of the bolus into the oesophagus triggers the pharyngeal constrictor muscles to contract from above downwards, propelling the bolus into the oesophagus. During this phase both the laryngeal inlet and the nasopharynx are closed to prevent aspiration and nasal regurgitation. The sensory input travels via the glossopharyngeal and vagus nerves.
Oesophageal stage
The oesophageal stage lasts 8–20 seconds; it begins with the bolus entering the oesophagus and ends when it has passed through the lower oesophageal sphincter into the stomach. Peristaltic waves can be primary, passing down the oesophagus, or secondary arising locally in response to distension of the oesophagus, helping transport the bolus through the oesophagus. Tertiary oesophageal contractions are irregular and non-propulsive, involving long segments of the oesophagus and frequently developing during emotional stress. The lower oesophageal sphincter is regulated by the vagus nerve.42