Auditory Ossicles Flashcards

Explore the malleus, incus, and stapes, including their articulations, attachments, muscles, embryology, and role in hearing.

Card 1 of 30Question

What are the auditory ossicles?

Three small bones in the middle ear that transmit vibrations from the tympanic membrane to the inner ear.

In This Section

1. What are the auditory ossicles?

Three small bones in the middle ear that transmit vibrations from the tympanic membrane to the inner ear.

2. What are the three auditory ossicles in lateral-to-medial order?

Malleus, incus, and stapes.

3. Where are the auditory ossicles located?

Within the tympanic cavity of the middle ear, in the temporal bone.

4. What is the primary function of the auditory ossicles?

To transmit and mechanically amplify sound-induced vibrations from the tympanic membrane to the oval window.

5. Which auditory ossicle is attached directly to the tympanic membrane?

The malleus, through its manubrium or handle.

6. What are the principal anatomical parts of the malleus?

The head, neck, manubrium, lateral process, and anterior process.

7. Which part of the malleus articulates with the incus?

The head of the malleus.

8. Which part of the malleus forms the prominence visible near the superior tympanic membrane?

The lateral process of the malleus.

9. Which muscle attaches to the manubrium of the malleus?

The tensor tympani muscle.

10. Which nerve supplies the tensor tympani muscle?

The nerve to medial pterygoid, a branch of the mandibular division of the trigeminal nerve (cranial nerve V3).

11. What is the action of the tensor tympani muscle?

It pulls the malleus medially, increasing tympanic membrane tension and reducing its vibration.

12. What are the principal anatomical parts of the incus?

The body, short crus, and long crus.

13. Which part of the incus articulates with the malleus?

The body of the incus.

14. Which part of the incus articulates with the stapes?

The lenticular process at the distal end of the long crus.

15. Where is the short crus of the incus anchored?

In the fossa incudis of the posterior tympanic cavity by the posterior ligament of the incus.

16. What are the principal anatomical parts of the stapes?

The head, neck, anterior crus, posterior crus, and footplate or base.

17. Which auditory ossicle is the smallest bone in the human body?

The stapes.

18. Which part of the stapes occupies the oval window?

The footplate, which is attached to the margins of the oval window by the annular ligament.

19. Which muscle attaches to the neck of the stapes?

The stapedius muscle.

20. Which nerve supplies the stapedius muscle?

The nerve to stapedius, a branch of the facial nerve (cranial nerve VII).

21. What is the primary action of the stapedius muscle?

It limits stapes movement at the oval window, reducing sound transmission to the inner ear.

22. What type of synovial joint connects the malleus and incus?

The incudomalleolar joint, commonly classified as a saddle-type synovial joint.

23. What type of joint connects the incus and stapes?

The incudostapedial joint, a small synovial joint between the lenticular process of the incus and the head of the stapes.

24. How do the auditory ossicles improve the transmission of sound into the inner ear?

They provide mechanical impedance matching through the tympanic membrane-to-stapes footplate area ratio and ossicular lever action.

25. What is the principal arterial supply of the auditory ossicles?

Small branches of the anterior tympanic, stylomastoid, and other tympanic arteries.

26. From which embryonic pharyngeal arch do the malleus and incus primarily develop?

The first pharyngeal arch, associated with Meckel's cartilage.

27. What is the embryological origin of the stapes?

Most of the stapes develops from the second pharyngeal arch, while the vestibular surface of its footplate has an otic capsule contribution.

28. What is otosclerosis?

Abnormal bone remodeling of the otic capsule that commonly fixes the stapes footplate at the oval window, causing conductive hearing loss.

29. Which auditory ossicular articulation is especially vulnerable to disruption after head trauma?

The incudostapedial joint, whose separation can interrupt sound conduction.

30. Why can facial nerve injury proximal to the nerve to stapedius cause hyperacusis?

Paralysis of the stapedius reduces attenuation of ossicular vibrations, making sounds seem abnormally loud.