Temporal Bone and Ear - Learning Objectives and Review Questions

True/False

1. The footplate of the stapes is oval shaped and is a meaningful way to remember that the stapes attaches to the oval window and not the round window.
2. The round window is essentially a fluid relief that enhances fluid dynamics within the inner ear middle ear.
3. The mucosal layer of the tympanic membrane faces the inner ear and sensation is provided by GVA fibers from the recurrent tympanic branch of the facial nerve.
4. Three bones make up the ossicular chain of the middle ear.
5. Dampening of the ossicular chain is provided for by SVE fibers from the trigeminal and facial nerves.
6. The chorda tympani nerve crossed the medial side of the incus and the lateral side of the malleus. (true)
7. The most medial extent of the external ear canal is marked by the external layer of the tympanic membrane.
8. The round window is filled with cartilage.
9. The geniculate ganglion is located along the horizontal part of the facial nerve and the chorda tympani from along the vertical (descending) part of the facial nerve.
10. The cochlea has 2.5 turns.
11. Despite debate over the protective efficacy of the tensor tympani and the stapedius, the is not debate that these muscles dampen the ossicle in the presence of loud noises.
12. There will not be a 15 point essay that asks to discuss the entire anatomy, relationships, and contents of the temporal bone. Nevertheless there will undoubtably be questions that require knowledge of the temporal bone - tmj joint, infratemporal fossa, base of skull, middle cranial fossa, and so on.
13. The vertical part of the facial nerve is closely related to the mastoid air cells.
14. The mastoid air cells equilibrate by way of the ostia of the auditory tube.
15. Middle ear infections may find their way to the cavernous sinus.
16. Aggressive excavation of the anterior medial wall of the mastoid air cells may endanger the sigmoid sinus.
17. The aditus provides a direct communication between the mastoid air cells and the oropharynx.
18. The medial wall of the mastoid antrum is shaped by the topography of the semicircular canals.
19. The tympanic membrane separates the external auditory meatus from the immediately adjacent inner ear.
20. It is advisable to limited piercing of the ear to the lobule because cartilage is not involved.
21. The ossicles are mechanically linked to the inner ear at the round window.
22. The manubrium of the malleus articulates with the clavicle of the ossicles.
23. The chorda tympani may be observed crossing the lateral surface of the tympanic membrane.
24. The ossicular chain decreases the movement of the stapes at the oval window relative to movement of the malleus at the umbo of the tympanic membrane.
25. The tensor tympani and stapedius muscles are credited with dampening and tuning sounds.
26. The ossicular chain is primarily located in the posterior superior quadrant of the middle ear.
27. The round window provides a relief for cochlear fluids.
28. Knowing that the stapes is shaped like a stirrup is an effective mnemonic for knowing that it attaches to the oval window.
29. The human cochlea houses the organ of Saint James and is known to have 4 turns.
30. The utricle and the saccule are otolithic organs.
31. The cochlear nerve and the facial nerve leave the posterior cranial fossa by entering the internal auditory meatus.
32. Crying in response to inhaling chili powder involves GSA fibers from the trigeminal nerve and GVE fibers from the facial nerve.
33. A lesion of the facial nerve distal to the stapedial branch and proximal to the chorda tympani branch will cause hyperacusis (SVE) but not disrupt taste (SVA) or salivation (GVE).
34. A lesion of the facial nerve distal to the chorda tympani branch but proximal to the stylomastoid foramen will spare SVA (taste) to the anterior 2/3 of the tongue but will disrupt GSA sensation to the external auditory meatus.
35. A lesion of the facial nerve at the stylomastoid foramen will cause paralysis of unilateral facial musculature but will not affect salivation.
36. A lesion of the facial nerve as it enters the parotid gland is expected to reduce salivation.
37. A lesion of the greater superficial petrosal nerve at the lacerate foramen will cause ipsilateral dry eye but will not affect sensitivity to loud noises.
38. An infection of the mastoid air cells could spread to the cavernous sinus if the sigmoid sinus is eroded.
39. Stapedius and tensor tympani are both involved with dampening the ossicles.
40. The stapedius is innervated by the facial nerve whereas the tensor tympani is innervated by the mandibular division of the trigeminal.
41. The stapes attaches to the round window.
42. The chorda tympani can be observed on otoscopic examination to cross the inferior anterior aspect of the tympanic membrane.
43. The external auditory canal is described as being 2/3 bone and 1/3 cartilage whereas the auditory tube is described as being 1/3 bone and 2/3 cartilage.
44. The facial nerve, a hard worker during the day, is often seen entering Bill's Bar.
45. The mastoid air cells, aditus, and auditory canal form a continuous airway the communicates with the nasopharynx.
46. The location of the superior semicircular canal can be seen, without bone dissection, on the petrous pyramid of the temporal bone.
47. The labyrinthine artery is considered to be an end artery.
48. For the most part, the helix borders the outer convexity of the antihelix.
49. The tragus is posterior to the antitragus.

Essay

1. Discuss the course of the facial nerve within the temporal bone. Include relationships, foramina, functional components, nerve distributions, and nerve embarrassment.
2. Discuss the mastoid air cells. Include relationships, foramina, nerve distributions, and communications. Briefly discuss surgical decompression of the facial nerve within the facial canal in relationship to the mastoid air cells and the sigmoid sinus.

Short Answer

1. Superior semicircular canal
2. Genu of the facial canal
3. Mastoid air cells
4. Aditus
5. Stapedius
6. Tensor tympani
7. Auditory tube