Final answer:
The dorsum sellae is not visible within the foramen magnum; instead, the occipital bone that surrounds the foramen magnum and the occipital condyles, which support the skull, are seen.
Step-by-step explanation:
When looking inside the foramen magnum, the structure known as the dorsum sellae is not visible as it is part of the sphenoid bone located in the middle cranial fossa, anterior to the foramen magnum. Instead, within the foramen magnum, you will primarily observe the occipital bone, which forms the posterior part of the skull and cranial cavity. The occipital bone features the foramen magnum at its base, allowing passage for the spinal cord, and is flanked by the occipital condyles on either side, which articulate with the first cervical vertebra.