The skull contains numerous openings called foramina, particularly the foramen magnum, which allow structures such as nerves and blood vessels to enter and leave the skull.e brain (the occipital, sphenoid, and ethmoid) are largely formed by endochondral ossification.
The skull contains numerous openings called foramina, particularly the foramen magnum, which allow structures such as nerves and blood vessels to enter and leave the skull. The endocranium, the bones supporting the brain (the occipital, sphenoid, and ethmoid) are largely formed by endochondral ossification.