Ear Anatomy (External, Middle, Inner Ear) MCQs

ENT · 67 free questions with answers & explanations.

1. During a canal wall up mastoidectomy, the surgeon encounters a bony ridge running from the posterior bony canal wall to the lateral semicircular canal. This ridge is called the:
2. The space of Prussak lies between which two structures?
3. The endocochlear potential (EP) of approximately +80 mV across the basilar membrane is maintained by the high K⁺ concentration of endolymph. Which ion channel is most critical for K⁺ recycling back to the stria vascularis after hair cell stimulation?
4. In the internal acoustic meatus (IAM), Bill's bar is a vertical bony crest that separates which two structures at the fundus?
5. The annular ligament attaches the footplate of the stapes to the oval window. Which type of joint best describes the stapes–oval window articulation?
6. The tensor tympani muscle is attached to the handle of the malleus and is innervated by which nerve?
7. In the inner ear, the electrolyte composition of endolymph closely resembles which intracellular fluid characteristic?
8. The blood supply to the cochlea is provided almost exclusively by which artery, making it extremely vulnerable to ischemia?
9. The tensor tympani muscle inserts into the medial surface of the handle of malleus. Its primary mechanical action when it contracts is to:
10. The chorda tympani nerve runs through the middle ear in a specific fascial fold. If it is injured during tympanomastoid surgery, the immediate neurological deficit NOT expected is:
11. In the inner ear, the endolymphatic sac is located:
12. The scala vestibuli and scala tympani communicate at the:
13. The stapedial reflex arc involves afferent input via the auditory nerve and efferent output via the facial nerve to the stapedius muscle. Which of the following correctly describes its ipsilateral and contralateral components?
14. The endolymph of the inner ear is secreted primarily by which structure, and what is its ionic composition compared to perilymph?
15. Which of the following correctly describes the blood supply to the cochlea and the consequence of its disruption?
16. In the middle ear, the tensor tympani muscle inserts on the manubrium of the malleus and is supplied by which nerve? What is its primary function?
17. A patient with chronic otitis media develops a defect in the posterior superior quadrant of the tympanic membrane exposing the area between the malleus handle and the posterior tympanic wall. This region corresponds to which anatomical space?
18. The scala media of the cochlea is separated from the scala vestibuli by which membrane, and what is the ionic composition of endolymph within it?
19. A 35-year-old presents after a blow to the auricle with a collection between perichondrium and cartilage. Which vessel supplies the auricular cartilage and explains why avascular necrosis can complicate untreated auricular hematoma?
20. The tensor tympani muscle is innervated by the nerve to medial pterygoid (branch of V3) and acts to dampen intense sounds. What is the primary bony landmark that separates it from the Eustachian tube in the anterior wall of the middle ear?
21. In testing the stapedius reflex (acoustic reflex), an ipsilateral reflex arc traverses which neural pathway from the stapedius muscle to the stimulus ear?
22. The endolymphatic sac is located in which anatomical compartment and is responsible for endolymph resorption. Dysfunction of this structure is implicated in the pathogenesis of which condition?
23. The tensor tympani muscle inserts into the medial surface of the handle of the malleus. Which nerve is responsible for its motor innervation?
24. During a middle ear surgery, a surgeon identifies the processus cochleariformis. What is the functional significance of this bony landmark?
25. The endolymphatic sac is responsible for which primary function in the inner ear?
26. A 35-year-old man sustains a temporal bone fracture. He develops a conductive hearing loss. The ossicular chain disruption most commonly involves:
27. The blood supply of the cochlea is derived from the labyrinthine artery. What is the clinical consequence of this vascular anatomy?
28. The blood supply to the stapes superstructure (crura and head) is derived primarily from:
29. The tensor tympani muscle is innervated by the nerve to medial pterygoid (mandibular nerve, CN V3). Its primary action when it contracts is to:
30. Regarding the endolymphatic sac, which of the following best describes its primary immunological function?
31. Type I fibrocytes of the spiral ligament are critically important for cochlear potassium homeostasis. Their role in the potassium recycling pathway is to:
32. The spiral ligament of the cochlea is located on which wall of the scala media and houses which critical structure for endolymph production?
33. The Prussak's space is a clinically important recess in the middle ear. Which of the following correctly describes its boundaries?
34. The perilymph in the scala vestibuli and scala tympani communicates through the helicotrema and ultimately drains via which structure?
35. During cortical mastoidectomy, the surgeon must identify Macewen's triangle (suprameatal triangle) to safely enter the mastoid antrum. Which of the following correctly identifies this triangle's landmarks?
36. The tensor tympani muscle inserts into the malleus and is innervated by which nerve, while its primary physiological action is:
37. The blood supply of the stapes superstructure is derived from the obturator artery, a branch of which vessel?
38. The endocochlear potential (ECP) in the scala media is approximately +80 mV and is generated by which structure?
39. The endolymph-filled scala media (cochlear duct) is separated from the perilymph-filled scala vestibuli by:
40. Tonotopic organization of the basilar membrane follows the principle that:
41. The blood supply to the cochlea comes exclusively from which artery?
42. The stapedius muscle is supplied by a branch of the facial nerve that arises from which segment?
43. The 'processus cochleariformis' is a bony landmark in the middle ear that serves as a pulley for which structure?
44. The endolymphatic sac is located in which anatomical compartment?
45. The blood supply to the lateral wall of the scala vestibuli and the stria vascularis is primarily derived from which vessel, and why is this clinically relevant in aminoglycoside ototoxicity?
46. The round window membrane in the middle ear has how many layers, and what is its significance in intratympanic drug delivery?
47. The endolymphatic duct passes through which bony canal connecting the membranous labyrinth to the endolymphatic sac?
48. The tensor tympani muscle is innervated by the medial pterygoid nerve (a branch of the mandibular nerve V3), but its tendon crosses the middle ear to insert on the handle of malleus. The stapedius muscle, which dampens loud sounds, is innervated by:
49. The scala media (cochlear duct) is separated from the scala vestibuli by Reissner's membrane and from the scala tympani by the basilar membrane. The endolymph within the scala media has an unusually high potassium concentration of approximately 150 mEq/L. Which structure is primarily responsible for maintaining this high K+ concentration?
50. During cortical mastoidectomy, the MacEwen's triangle is used as a surface landmark to locate the mastoid antrum. The three boundaries of MacEwen's triangle are:
51. The processus cochleariformis (cochleariform process) is an important surgical landmark in the middle ear. Its significance lies in its relationship to which structure?
52. The apical turn of the cochlea encodes which sound frequency, and what is the physiological basis for this tonotopic organization?
53. Prussak's space (superior recess of the tympanic membrane) is the most common site of origin of pars flaccida cholesteatoma. Which anatomical structure forms the roof of Prussak's space?
54. The Prussak's space (superior recess of the tympanic membrane) is bounded superiorly by Shrapnell's membrane. Which of the following is its medial boundary?
55. The blood supply of the stapes is derived from which artery in most individuals?
56. The scala media (cochlear duct) contains endolymph. Which cells primarily produce endolymph?
57. The pyramidal eminence in the middle ear contains the:
58. The endolymphatic duct drains endolymph from the membranous labyrinth to the endolymphatic sac, which is located:
59. The lateral wall of the epitympanum (attic) is formed by which structure?
60. A 30-year-old patient undergoes exploratory tympanotomy. The surgeon identifies a structure passing between the tensor tympani muscle and the handle of malleus. This landmark is most likely:
61. The processus cochleariformis serves as the landmark for which important surgical structure during mastoidectomy?
62. The endolymph of the membranous labyrinth is produced primarily by which structure?
63. Which bony landmark in the middle ear immediately overlies the promontory and represents the basal turn of the cochlea?
64. The tensor tympani muscle is innervated by the medial pterygoid nerve (a branch of V3) and attaches to the malleus. Contraction of the tensor tympani results in:
65. The membranous labyrinth of the inner ear is filled with endolymph. Endolymph is uniquely high in potassium and low in sodium, resembling intracellular fluid. The structure responsible for actively secreting endolymph is:
66. The blood supply of the stapes footplate is derived primarily from:
67. The tensor tympani muscle is innervated by: