The Structure and function of the ear MCQs With Answer introduction: Understanding ear anatomy and physiology is essential for B.Pharm students involved in pharmacotherapy of auditory and vestibular disorders. This concise review covers outer, middle and inner ear structures—tympanic membrane, ossicles, cochlea, organ of Corti, semicircular canals and vestibular organs—and key functions such as sound transmission, mechanotransduction, frequency mapping on the basilar membrane, and balance sensing. Clinical and pharmacological topics include audiometric tests, conductive versus sensorineural hearing loss, ototoxic drugs (aminoglycosides, loop diuretics), intratympanic therapy, and common pathologies like otitis media and otosclerosis. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which layer of the tympanic membrane contains fibrous connective tissue responsible for its tensile strength?
- Keratinized epithelial layer
- Fibrous (middle) layer
- Mucosal (inner) layer
- Cartilaginous layer
Correct Answer: Fibrous (middle) layer
Q2. What is the correct lateral-to-medial order of the middle ear ossicles?
- Stapes, incus, malleus
- Malleus, incus, stapes
- Incus, malleus, stapes
- Malleus, stapes, incus
Correct Answer: Malleus, incus, stapes
Q3. The primary function of the Eustachian tube is:
- Transduce sound into neural signals
- Equalize middle ear pressure with atmospheric pressure
- Pump endolymph within the cochlea
- Absorb acoustic energy to protect the inner ear
Correct Answer: Equalize middle ear pressure with atmospheric pressure
Q4. Which structure houses the sensory hair cells for hearing?
- Saccule
- Organ of Corti
- Endolymphatic sac
- Promontory
Correct Answer: Organ of Corti
Q5. Which fluid is high in potassium and bathes the stereocilia of hair cells in the scala media?
- Perilymph
- Cerebrospinal fluid
- Endolymph
- Interstitial fluid
Correct Answer: Endolymph
Q6. The three scalae of the cochlea are:
- Scala vestibuli, scala media, scala tympani
- Scala utriculi, scala sacculi, scala cochleari
- Scala externa, scala interna, scala media
- Scala tympani, scala basilaris, scala vestibuli
Correct Answer: Scala vestibuli, scala media, scala tympani
Q7. According to place theory, high-frequency sounds maximally displace which part of the basilar membrane?
- Apical (distal) end
- Middle turn
- Basal (near base) end
- Uniformly along the membrane
Correct Answer: Basal (near base) end
Q8. Which hair cells primarily transduce mechanical vibrations into neural signals to the auditory nerve?
- Outer hair cells
- Inner hair cells
- Supporting Deiters cells
- Border cells
Correct Answer: Inner hair cells
Q9. The stapedius muscle reflex primarily protects the inner ear from:
- Low-frequency sustained sounds only
- Loud sounds by reducing stapes movement
- Changes in endolymph composition
- Middle ear infections
Correct Answer: Loud sounds by reducing stapes movement
Q10. The ascending auditory pathway from the cochlear nucleus next projects to which nucleus for binaural processing?
- Medial geniculate body
- Superior olivary complex
- Inferior colliculus
- Primary auditory cortex
Correct Answer: Superior olivary complex
Q11. The primary auditory cortex (Heschl’s gyrus) is located in which lobe of the cerebral cortex?
- Frontal lobe
- Parietal lobe
- Temporal lobe
- Occipital lobe
Correct Answer: Temporal lobe
Q12. A perforated tympanic membrane with ossicular discontinuity most likely causes which type of hearing loss?
- Sensorineural hearing loss
- Neural conduction block
- Central auditory processing disorder
- Conductive hearing loss
Correct Answer: Conductive hearing loss
Q13. In Weber’s test, lateralization of the sound to the affected ear suggests what when combined with Rinne showing BC > AC in the affected ear?
- Normal hearing
- Sensorineural hearing loss on affected side
- Conductive hearing loss on affected side
- Central lesion
Correct Answer: Conductive hearing loss on affected side
Q14. Which antibiotic class is most commonly associated with cochlear hair cell ototoxicity?
- Beta-lactams
- Aminoglycosides
- Fluoroquinolones
- Tetracyclines
Correct Answer: Aminoglycosides
Q15. Which loop diuretic is known to cause reversible or permanent hearing loss at high doses?
- Hydrochlorothiazide
- Spironolactone
- Furosemide
- Amiloride
Correct Answer: Furosemide
Q16. Intratympanic steroid injections are used clinically for:
- Treating fungal otitis externa
- Systemic hypertension control
- Sudden sensorineural hearing loss and Meniere’s disease
- Repairing tympanic membrane perforation
Correct Answer: Sudden sensorineural hearing loss and Meniere’s disease
Q17. Which cochlear structure actively secretes potassium into the endolymph to maintain the endocochlear potential?
- Organ of Corti
- Stria vascularis
- Basilar membrane
- Reissner’s membrane
Correct Answer: Stria vascularis
Q18. The endolymphatic sac primarily contributes to which function?
- Sound transduction
- Immune defense and fluid homeostasis of the inner ear
- Transmitting ossicular vibrations
- Amplifying high-frequency sounds
Correct Answer: Immune defense and fluid homeostasis of the inner ear
Q19. The semicircular canals detect which type of motion?
- Static tilt relative to gravity
- Linear acceleration only
- Angular (rotational) acceleration
- Acoustic pressure waves
Correct Answer: Angular (rotational) acceleration
Q20. Utricle and saccule are specialized for detecting:
- Angular acceleration only
- Linear acceleration and head tilt (gravity)
- Cochlear micromechanics
- Middle ear pressure changes
Correct Answer: Linear acceleration and head tilt (gravity)
Q21. Deflection of stereocilia toward the tallest row opens mechanoelectrical transduction channels allowing which ion to enter hair cells from endolymph?
- Sodium (Na+)
- Chloride (Cl-)
- Potassium (K+)
- Calcium (Ca2+) exclusively
Correct Answer: Potassium (K+)
Q22. Which mechanism underlies the cochlear amplifier provided by outer hair cells?
- Active motility via prestin-mediated electromotility
- Secretion of endolymph
- Synaptic transmission to vestibular nerve
- Passive vibration only
Correct Answer: Active motility via prestin-mediated electromotility
Q23. The ossicular chain improves auditory sensitivity by providing which physical benefit?
- Thermal insulation
- Acoustic impedance matching between air and cochlear fluids
- Endolymph circulation
- Neural signal amplification
Correct Answer: Acoustic impedance matching between air and cochlear fluids
Q24. Barotrauma commonly results from dysfunction of which structure?
- Organ of Corti
- Eustachian tube
- Semicircular canals
- Endolymphatic sac
Correct Answer: Eustachian tube
Q25. A cholesteatoma in the middle ear consists of which tissue type that can erode ossicles?
- Inflamed mucosa
- Keratinizing squamous epithelium with debris
- Cartilaginous overgrowth
- Fibrous scar tissue only
Correct Answer: Keratinizing squamous epithelium with debris
Q26. Tympanometry primarily assesses which property of the middle ear system?
- Cochlear hair cell function
- Tympanic membrane mobility and middle ear compliance
- Vestibular reflex integrity
- Auditory brainstem conduction time
Correct Answer: Tympanic membrane mobility and middle ear compliance
Q27. In auditory brainstem responses (ABR), Wave I originates from which structure?
- Inferior colliculus
- Medial geniculate body
- Distal auditory (cochlear) nerve
- Primary auditory cortex
Correct Answer: Distal auditory (cochlear) nerve
Q28. A common genetic cause of congenital non-syndromic sensorineural hearing loss is mutation in which gene?
- GJB2 (connexin 26)
- MYH7
- CFTR
- BRCA1
Correct Answer: GJB2 (connexin 26)
Q29. First-line pharmacologic therapy often used to reduce vertigo attacks in Meniere’s disease includes:
- Aminoglycoside injections
- Betahistine and diuretics
- High-dose loop diuretics only
- Systemic broad-spectrum antibiotics
Correct Answer: Betahistine and diuretics
Q30. Otosclerosis primarily affects which structure leading to conductive hearing loss?
- Basilar membrane
- Stapes footplate fixation in the oval window
- Organ of Corti hair cells
- Endolymphatic duct
Correct Answer: Stapes footplate fixation in the oval window
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