Vestibule Flashcards

Examine the vestibule of the inner ear, including its bony walls, utricle, saccule, sensory receptors, nerve supply, and role in equilibrium.

Card 1 of 30Question

What is the vestibule of the inner ear?

The central chamber of the bony labyrinth that contains the utricle and saccule, which detect linear acceleration and head position relative to gravity.

In This Section

1. What is the vestibule of the inner ear?

The central chamber of the bony labyrinth that contains the utricle and saccule, which detect linear acceleration and head position relative to gravity.

2. Where is the vestibule located?

Within the petrous part of the temporal bone, between the cochlea anteriorly and semicircular canals posteriorly.

3. To which major anatomical division of the inner ear does the vestibule belong?

The bony labyrinth.

4. Which two membranous structures are housed within the vestibule?

The utricle and saccule.

5. Which fluid surrounds the utricle and saccule within the bony vestibule?

Perilymph.

6. Which fluid fills the utricle and saccule?

Endolymph, a potassium-rich fluid within the membranous labyrinth.

7. What is the principal sensory function of the utricle and saccule?

Detection of linear acceleration and static head orientation relative to gravity.

8. Which vestibular organ primarily detects horizontal linear acceleration when the head is upright?

The utricle.

9. Which vestibular organ primarily detects vertical linear acceleration when the head is upright?

The saccule.

10. What is the macula of a vestibular organ?

A specialized sensory epithelial region containing vestibular hair cells and supporting cells.

11. How is the macula of the utricle typically oriented in the upright head?

Approximately horizontally.

12. How is the macula of the saccule typically oriented in the upright head?

Approximately vertically.

13. What is the otolithic membrane?

A gelatinous layer overlying the macular hair cells and containing calcium carbonate crystals called otoconia.

14. What are otoconia?

Small calcium carbonate crystals embedded in the otolithic membrane that increase its mass and sensitivity to gravity and linear acceleration.

15. How do linear acceleration and gravity stimulate the macular hair cells?

They cause displacement of the otolithic membrane relative to the sensory epithelium, bending the hair cell bundles.

16. What happens when vestibular hair cell stereocilia bend toward the kinocilium?

The hair cell depolarizes, increasing neurotransmitter release onto vestibular afferent fibers.

17. What is the striola of a vestibular macula?

A curved zone within the macula where the orientation of hair cell polarity changes.

18. Which depression in the medial vestibular wall accommodates the utricle?

The elliptical recess, also called the recessus ellipticus.

19. Which depression in the medial vestibular wall accommodates the saccule?

The spherical recess, also called the recessus sphericus.

20. What is the vestibular crest?

A bony ridge on the medial wall of the vestibule separating the elliptical and spherical recesses.

21. Which opening in the lateral vestibular wall receives the stapes footplate?

The oval window, also called the fenestra vestibuli.

22. How many openings connect the bony semicircular canals with the vestibule?

Five openings, because the anterior and posterior semicircular canals share a common crus.

23. How does the utricle communicate with the membranous semicircular ducts?

The semicircular ducts open directly into the utricle.

24. How does the saccule communicate with the cochlear duct?

Through the ductus reuniens.

25. What structure connects the utricle and saccule to the endolymphatic duct?

The utriculosaccular duct, formed by the union of the utricular and saccular ducts.

26. Which cranial nerve carries sensory information from the utricle and saccule?

The vestibular division of the vestibulocochlear nerve (cranial nerve VIII).

27. Which vestibular nerve divisions primarily carry sensory information from the utricle and saccule?

The superior vestibular nerve supplies most of the utricle, while the inferior vestibular nerve supplies most of the saccule.

28. Where are the cell bodies of the primary sensory neurons supplying the vestibule located?

In the vestibular ganglion, also called Scarpa's ganglion, within the internal acoustic meatus.

29. Which artery provides the principal blood supply to the vestibular organs?

The labyrinthine artery, usually arising from the anterior inferior cerebellar artery, through its vestibular branches.

30. How are displaced utricular otoconia associated with benign paroxysmal positional vertigo?

Detached otoconia may enter a semicircular duct and produce abnormal stimulation during head movements, causing positional vertigo.