Sphenoid Flashcards

Explore the sphenoid bone's body, wings, pterygoid processes, cranial foramina, muscular attachments, and neurovascular relationships.

Card 1 of 30Question

Where is the sphenoid bone located?

In the central cranial base, posterior to the ethmoid bone and anterior to the occipital bone.

In This Section

1. Where is the sphenoid bone located?

In the central cranial base, posterior to the ethmoid bone and anterior to the occipital bone.

2. Why is the sphenoid bone called the keystone of the cranial base?

It articulates with all other cranial bones and helps connect the anterior, middle, and posterior regions of the skull.

3. What are the major anatomical parts of the sphenoid bone?

The body, paired greater wings, paired lesser wings, and paired pterygoid processes.

4. Which cranial fossa is primarily formed by the body and greater wings of the sphenoid bone?

The middle cranial fossa.

5. Which parts of the sphenoid bone contribute to the posterior boundary of the anterior cranial fossa?

The posterior borders of the lesser wings and the anterior clinoid processes.

6. What is the sella turcica?

A saddle-shaped depression on the superior surface of the sphenoid body.

7. Which structure occupies the hypophyseal fossa of the sella turcica?

The pituitary gland.

8. What is the tuberculum sellae?

A bony elevation forming the anterior boundary of the hypophyseal fossa.

9. What is the dorsum sellae?

A vertical bony plate forming the posterior boundary of the sella turcica.

10. Which projections extend from the superior corners of the dorsum sellae?

The posterior clinoid processes.

11. Where are the sphenoidal sinuses located?

Within the body of the sphenoid bone, inferior to the sella turcica.

12. Where do the sphenoidal sinuses drain?

Into the sphenoethmoidal recesses, superior and posterior to the superior nasal conchae.

13. Which major vascular structure lies along each lateral side of the sphenoid body?

The cavernous segment of the internal carotid artery, within the cavernous sinus.

14. Which part of the sphenoid bone contributes to the lateral wall of the skull and the temporal fossa?

The greater wing.

15. Which opening between the greater and lesser wings communicates with the orbit?

The superior orbital fissure.

16. Which cranial nerves pass through the superior orbital fissure?

The oculomotor (III), trochlear (IV), ophthalmic (V1), and abducens (VI) nerves.

17. Which structures pass through the optic canal of the sphenoid bone?

The optic nerve (cranial nerve II) and ophthalmic artery.

18. Which nerve passes through the foramen rotundum?

The maxillary nerve (V2), entering the pterygopalatine fossa.

19. Which nerve passes through the foramen ovale?

The mandibular nerve (V3).

20. Which artery passes through the foramen spinosum?

The middle meningeal artery, accompanied by the middle meningeal vein and meningeal branch of the mandibular nerve.

21. What occupies the foramen lacerum in the living skull?

It is largely filled with fibrocartilage, with the internal carotid artery passing across its superior aspect.

22. What are the two plates of each pterygoid process?

The medial and lateral pterygoid plates.

23. Which muscle originates primarily from the lateral surface of the lateral pterygoid plate?

The inferior head of the lateral pterygoid muscle.

24. Which muscle originates from the medial surface of the lateral pterygoid plate?

The deep head of the medial pterygoid muscle.

25. What is the pterygoid hamulus?

A hook-shaped projection at the inferior end of the medial pterygoid plate.

26. Which tendon curves around the pterygoid hamulus?

The tendon of the tensor veli palatini muscle.

27. Which structures traverse the pterygoid canal?

The nerve, artery, and vein of the pterygoid canal.

28. Which bones articulate with the sphenoid bone?

The frontal, ethmoid, occipital, parietal, temporal, zygomatic, palatine, and vomer bones.

29. What is the spheno-occipital synchondrosis?

A cartilaginous growth plate between the sphenoid body and basilar occipital bone that normally fuses after adolescence.

30. Why is the sphenoidal sinus important in transsphenoidal pituitary surgery?

It provides an anatomical route to the sella turcica, allowing surgical access to the pituitary gland.