The |occipital bone| forms the back of the |skull| and the cranial base. It is joined to the two |parietal bones| and to the |mastoid processes| of the |temporal bones| on the side by the |lambdoid suture|. At the base of the |occipital bone|, at the |basilar parts|, the |occipital bone| is attached to the |sphenoid bone|. The |occipital bone| features a significant bump, or |external occipital protuberance|, in the center of the back of the |skull|, while the Nuchal line (a low, bony ridge) defines the cusp at which the |occipital bone| curves under to the base. The large opening, or |foramen magnum|, in the |occipital bone| can be seen in the inferior view of the |skull|, and allows the ~nerves~ of the upper |spinal cord| to pass through the |skull| between the |brain| and the rest of the |spinal cord|.
