HEENT 02: Throat, Nose, Sinus, Middle Ear

Question 1

Describe the structure of the nose and nasal cavity.

Answer 1

• 3 conchae (turbinates) or curved bone shelves to slow air flow
• covered with mucosal epithelium, separated by meatuses (spaces)
• warms and humidifies air entering body
• nose hairs filter out large particles (> 30 mm)

Question 2

Describe the structure of nasal mucosa layer.

Answer 2

• attached to periosteum (bone) or perichondrium (cartilage) by highly vascularized connective tissue
• blood supply from ethmoidal (internal carotid), sphenopalatine, greater palatine, labial and nasal arteries (external carotid)

Question 3

Describe the parasympathetic mucosal innervation.

Answer 3

• from pterygopalatine ganglion
• stimulation causes non-cholinergic vasodilation, increases mucus production

Question 4

Describe the sympathetic mucosal innervation.

Answer 4

• from superior cervical ganglion
• stimulation causes constriction of mucosal vessels (tone)
• nasal congestion occurs upon withdrawal of sympathetic input

Question 5

Describe the sensory innervation of the nasal mucosa.

Answer 5

• nasopalatine (V2) and nasociliary (V1) branches of trigeminal nerve
• mediate pain, pruritis, response to inhaled irritants
• olfactory nerve innervates for sense of smell

Question 6

What are the 3 types of cells of the ciliary epithelium?

Answer 6

• ciliated columnar epithelial cells
• goblet cells
• basal cells

Question 7

What do ciliated columnar epithelial cells do?

Answer 7

cilia move in mucous blanket to promote removal of particulate matter to nasopharynx where it is swallowed

Question 8

What do goblet cells do?

Answer 8

secrete glycoproteins (mucin)

Question 9

What do basal cells do?

Answer 9

attach mucous epithelium submucosal tissues

Question 10

What is mucous composed of?

Answer 10

• 95% water
• glycoproteins, electrolytes, enzymes, anti-enzymes, antioxidants, antibacterial agents, lipids, and cellular mediators derived from submucosal glands and plasma extravasation (antibodies, etc.)
• pH 5.5-6.5

Question 11

What is the submucosal (sero-mucous) gland?

Answer 11

• mucous excretion is increased by activation of parasympathetic nervous system
• M2 and M3 receptors
• sensory nerve endings in epithelium detect inhaled irritants
• neurogenic release of substance P and neurokinin A neuropeptides can increase mucous production through activation of NK1 receptor (also vasodilatory)

Question 12

What do M2 receptors do?

Answer 12

mediate increased mucous production

Question 13

What do M3 receptors do?

Answer 13

inhibit mucous production (by inhibition of acetylcholine release)

Question 14

What type of receptors do olfactory neurons contain?

Answer 14

one type of GPCR – activated by particular odorant

Question 15

What is allergic rhinitis?

Answer 15

inflammation of nasal mucosa

Question 16

What are the symptoms of allergic rhinitis?

Answer 16

itching, sneezing, nasal discharge, nasal blockage

Question 17

Describe the pathogenesis of allergic rhinitis.

Answer 17

• IgE-mediated through environmental factors in genetically predisposed individuals
• allergens reacting with IgE on surface of nasal mucosal mast cells and basophils cause degranulation and release of histamine and inflammatory mediators

Question 18

What does histamine do in allergic rhinitis?

Answer 18

acts on nasal mucosa to cause nasal blockage, sneezing, pruritis, and rhinorrhea

• H1 receptor activation mediates allergen-induced symptoms
• H3 receptor activation contributes to nasal stuffiness by inhibition of release of noradrenaline by sympathetic efferent fibers

Question 19

What is pruritus and sneezing (reflex) mediated by?

Answer 19

activation of trigeminal nerves

Question 20

What is rhinorrhea due to?

Answer 20

increased vascular permeability (plasma exudate) and increased glandular secretions (containing lactoferrin and lysozymes) mediated by increased parasympathetic tone

Question 21

How does inflammation affect nasal passages?

Answer 21

slows mucuciliary clearance, increases blood flow and vascular permeability, and decreases diameter of nasal passages

Question 22

Describe the structure of paransal sinuses.

Answer 22

• paired, air filled, cavities near nasal cavity
• lined with ciliated, pseudostratified columnar epithelium that is continuous with nose
• frontal, maxillary, and anterior ethmoid sinuses drain to middle meatus
• posterior ethmoid and sphenoid sinuses drain to superior meatus

Question 23

What do the paransal sinuses do? (3)

Answer 23

• produce mucous
• lighten skull
• aid in sound transmission

Question 24

What is sinusitis (rhinosinusitis)?

Answer 24

inflammation of mucosal epithelium of nose and sinuses

Question 25

What is acute rhinosinusitis?

Answer 25

< 4 weeks - viral: rhinovirus (more common) - bacterial: S. pneumoniae, H. influenzae, M. catarrhalis (more rare) - nasal obstruction and discharge, changes in smell, facial pain/pressure, pain worsens with bending and can radiate to teeth - results in edema, obstruction, and decreased mucociliary activity

Question 26

What is chronic rhinosinusitis?

Answer 26

> 12 weeks - differentiated by presence of nasal polyps – outgrowths of edematous inflammatory tissue that have grown into middle meatus - cough and fatigue common - moderate to severe pain is not common

Question 27

Describe the structure of the nasopharynx.

Answer 27

- connects nasal passage to larynx - lined with mucosal epithelium - drains sinuses, lymph, and auditory tubes - pharyngeal tonsil: mucosal epithelium has M cells that transmit antigens to lymphoid - soft palate: closes nasal passage during swallowing

Question 28

Describe the structure of the oropharynx.

Answer 28

connects mouth to esophagus

Question 29

Describe the structure of the nasopharynx.

Answer 29

- epiglottis closes larynx during swallowing to prevent aspiration - common passageway for food and air

Question 30

What is pharyngitis?

Answer 30

inflammation of the pharynx (sore throat) - often secondary to infection – rhinovirus, streptococcus, candida - pharyngeal erythema and swelling, tonsillar exudate, edematous uvula

Question 31

What pathogens cause pharyngitis?

Answer 31

- children (5-15): Streptococcus pyogenes - group A hemolytic streptococcal pharyngitis pharyngeal erythema and swelling, tonsillar exudate, edematous uvula untreated: lasts 10 days, and infectious for 7 days

Question 32

What happens if pharyngitis is not treated?

Answer 32

lasts 10 days, and infectious for 7 days

Question 33

Describe the structure and function of the external ear (auricle or pinna).

Answer 33

- lies at outer end of short tube called external acoustic meatus - collects sound waves and funnels them through to external acoustic meatus to tympanic membrane

Question 34

Describe the structure and function of the tympanic membrane (eardrum).

Answer 34

- circular structure at internal end of external acoustic meatus - energy of sound wave is converted into vibration of tympanic membrane

Question 35

What is the function of the middle ear?

Answer 35

transmit and amplify vibrations from tympanic membrane to inner ear

Question 36

What are the 3 ossicles of the middle ear?

Answer 36

- malleus: attached to internal surface of tympanic membrane - incus: connects malleus with stapes - stapes: attaches to vestibular (oval or cochlear) window, stapedius muscle prevents excess movement of stapes and controls amplitude of sound waves from external environment to middle ea

Question 37

Describe the connection between the middle ear and auditory tube.

Answer 37

- middle ear is filled with air - auditory tube is normally closed – opens during yawning or swallowing to allow equalization of pressure in middle ear (may hear soft pop sound at high altitude)

Question 38

Why is acute otitis media common in children?

Answer 38

short auditory (eustachian) tube - increases risk of infected secretions reaching middle ear - daycare is risk factor

Question 39

What are the signs and symptoms of acute otitis media?

Answer 39

- results in bulging of tympanic membrane - may be associated with localized pain, headache, fever, nausea, vomiting

Question 40

What pathogens cause acute otitis media?

Answer 40

S. pneumoniae, H. influenzae, M catarrhalis - occurs frequently after viral upper respiratory infection

Question 41

What is mastoiditis?

Answer 41

spread of acute otitis media infection to mastoid bone - can occur without AOM treatment

Question 42

What are the 2 functional organs of the inner ear (vestibule)?

Answer 42

- cochlea: coiled tube divided into 3 chambers that transduces sound for hearing - vestibular apparatus: semicircular canals (sense rotation), otolith organs (sense gravity and linear movement)

Question 43

What detects sound and motion in the inner ear?

Answer 43

hair cells

Question 44

What is drug-induced ototoxicity?

Answer 44

damaging effect of medication on auditory or vestibular organs resulting in hearing loss and/or balance problems

Question 45

What drugs can induce ototoxicity?

Answer 45

aminoglycosides – tobramycin, gentamicin - some agents affect vestibular apparatus and some affect cochlea - risk increases with total drug exposure

Question 46

What is vestibulotoxicity?

Answer 46

typically manifests with ataxia, dysequilibrium and oscillopsia (visual blurring with head movement) - can be detected by Dynamic Illegible E test:

Question 47

What is chocleotoxicity?

Answer 47

- may be detected by loss of response to high frequency sound - aminoglycosides are irreversible ototoxins that cause hair cell dysfunction and death – possibly by promoting oxygen radical formation - affect outer hair cells of cochlea more than inner hair cells - innermost hair cells or apex of vestibular organs are affected before peripheral hair cells