Foramen Magnum Flashcards

Examine the foramen magnum's bony boundaries, neurovascular contents, ligament attachments, craniovertebral relationships, and clinical anatomy.

Card 1 of 28Question

What is the foramen magnum?

The largest opening in the cranial base, connecting the posterior cranial fossa with the vertebral canal.

In This Section

1. What is the foramen magnum?

The largest opening in the cranial base, connecting the posterior cranial fossa with the vertebral canal.

2. Which bone contains the foramen magnum?

The occipital bone.

3. In which cranial fossa is the foramen magnum located?

The posterior cranial fossa.

4. Which part of the occipital bone forms the anterior boundary of the foramen magnum?

The basilar part of the occipital bone.

5. Which parts of the occipital bone form the lateral boundaries of the foramen magnum?

The paired lateral parts of the occipital bone.

6. Which part of the occipital bone forms the posterior boundary of the foramen magnum?

The squamous part of the occipital bone.

7. Which major neural structure passes through the foramen magnum?

The medulla oblongata, continuing inferiorly as the spinal cord.

8. At approximately what level does the medulla oblongata become continuous with the spinal cord?

Near the foramen magnum, approximately at the level of the first cervical nerve roots.

9. Which major paired arteries enter the cranial cavity through the foramen magnum?

The vertebral arteries.

10. Which spinal arteries pass through the foramen magnum?

The anterior and posterior spinal arteries.

11. Which cranial nerve roots ascend through the foramen magnum?

The spinal roots of the accessory nerve (cranial nerve XI).

12. What is the course of the spinal accessory nerve after entering the cranial cavity?

It ascends through the foramen magnum and exits the skull through the jugular foramen.

13. Which meningeal layers continue through the foramen magnum around the spinal cord?

The dura mater, arachnoid mater, and pia mater.

14. Which structures lie immediately lateral to the foramen magnum on the inferior skull?

The paired occipital condyles.

15. Which vertebra articulates with the occipital condyles beside the foramen magnum?

The atlas, or first cervical vertebra (C1).

16. Which ligament extends from the anterior arch of the atlas to the anterior margin of the foramen magnum?

The anterior atlanto-occipital membrane.

17. Which membrane connects the posterior arch of the atlas to the posterior margin of the foramen magnum?

The posterior atlanto-occipital membrane.

18. Which ligament attaches to the anterior margin of the foramen magnum and continues inferiorly along the vertebral bodies?

The anterior longitudinal ligament.

19. Which ligament extends from the axis to the basilar occipital bone inside the foramen magnum?

The tectorial membrane, a superior continuation of the posterior longitudinal ligament.

20. Where does the apical ligament of the dens attach superiorly?

To the anterior margin of the foramen magnum near the basion.

21. Which ligaments connect the dens of the axis to the occipital bone near the foramen magnum?

The paired alar ligaments, attaching to the medial surfaces of the occipital condyles.

22. What is the basion?

The midpoint of the anterior margin of the foramen magnum.

23. What is the opisthion?

The midpoint of the posterior margin of the foramen magnum.

24. Which canal lies superior to each occipital condyle near the foramen magnum?

The hypoglossal canal, transmitting the hypoglossal nerve (cranial nerve XII).

25. What is foramen magnum stenosis?

Abnormal narrowing of the foramen magnum that may compress the cervicomedullary junction.

26. What is the relationship between Chiari type I malformation and the foramen magnum?

The cerebellar tonsils descend through the foramen magnum into the upper cervical spinal canal.

27. What is tonsillar herniation through the foramen magnum?

Downward displacement of the cerebellar tonsils that can compress the medulla and threaten vital functions.

28. What is the clinical significance of basilar invagination?

Upward displacement of the upper cervical spine toward the foramen magnum may compress the brainstem.