Ethmoid Bone Flashcards

Examine the ethmoid bone's cribriform plate, crista galli, perpendicular plate, ethmoidal air cells, nasal conchae, and orbital relationships.

Card 1 of 30Question

Where is the ethmoid bone located?

In the anterior cranial base, between the orbits and superior to the nasal cavity.

In This Section

1. Where is the ethmoid bone located?

In the anterior cranial base, between the orbits and superior to the nasal cavity.

2. What type of bone is the ethmoid bone?

An unpaired, irregular, pneumatized bone of the neurocranium.

3. What are the four principal components of the ethmoid bone?

The cribriform plate, perpendicular plate, and two ethmoidal labyrinths.

4. Which part of the ethmoid bone contributes to the anterior cranial fossa floor?

The cribriform plate.

5. Which nerve fibers traverse the foramina of the cribriform plate?

Olfactory nerve fibers (cranial nerve I).

6. What is the crista galli?

A vertical midline bony projection extending superiorly from the cribriform plate.

7. Which dural structure attaches to the crista galli?

The falx cerebri.

8. Which part of the ethmoid bone contributes to the nasal septum?

The perpendicular plate.

9. Which bone articulates with the inferior border of the perpendicular plate?

The vomer.

10. What are the ethmoidal labyrinths?

Paired lateral masses containing the ethmoidal air cells.

11. What are the ethmoidal air cells?

Multiple air-filled cavities within the ethmoidal labyrinths that form the ethmoidal paranasal sinuses.

12. Which part of the ethmoid bone forms much of the medial orbital wall?

The orbital plate, also called the lamina papyracea.

13. Why is the lamina papyracea clinically significant?

Its thin structure permits infection or trauma to extend between the ethmoidal sinuses and orbit.

14. Which two nasal conchae are normally parts of the ethmoid bone?

The superior and middle nasal conchae.

15. Is the inferior nasal concha part of the ethmoid bone?

No. The inferior nasal concha is a separate facial bone.

16. What is the uncinate process of the ethmoid bone?

A thin, hook-shaped bony projection from the lateral nasal wall that helps form the ethmoidal infundibulum.

17. What is the ethmoidal bulla?

A rounded elevation on the lateral wall of the middle nasal meatus formed by underlying ethmoidal air cells.

18. What is the hiatus semilunaris?

A curved cleft in the middle nasal meatus between the ethmoidal bulla and uncinate process.

19. Where do the anterior ethmoidal air cells drain?

Into the middle nasal meatus, commonly through the ethmoidal infundibulum.

20. Where do the middle ethmoidal air cells typically drain?

Into the middle nasal meatus, often on or near the ethmoidal bulla.

21. Where do the posterior ethmoidal air cells drain?

Into the superior nasal meatus.

22. Which arteries supply the ethmoidal air cells?

The anterior and posterior ethmoidal arteries, branches of the ophthalmic artery.

23. Which nerves provide general sensory innervation to the ethmoidal sinuses?

The anterior and posterior ethmoidal nerves from the nasociliary branch of the ophthalmic nerve (V1).

24. Which ethmoidal foramina transmit vessels and nerves between the orbit and ethmoidal region?

The anterior and posterior ethmoidal foramina.

25. Which bones articulate with the ethmoid bone?

The frontal, sphenoid, vomer, nasal, maxillary, lacrimal, palatine, and inferior nasal conchal bones.

26. What is a concha bullosa?

Pneumatization of a nasal concha, most commonly the middle nasal concha.

27. How can a fracture of the cribriform plate affect the sense of smell?

It may tear olfactory nerve fibers, causing reduced or absent smell.

28. What is cerebrospinal fluid rhinorrhea following ethmoid bone trauma?

Leakage of cerebrospinal fluid into the nasal cavity through a defect in the skull base and meninges.

29. What is the fovea ethmoidalis?

The orbital plate of the frontal bone forming the roof of the ethmoidal air cells.

30. Why is the lateral lamella of the cribriform plate important in endoscopic sinus surgery?

It is a thin, vulnerable part of the anterior skull base where injury can cause a cerebrospinal fluid leak.