Answer
The occipital bone is located at the posterior of the cranium. It forms part of the roof and most of the base of the skull. There are several openings in the base of the structure, but the most prominent and important is the foramen magnum. The spinal cord (SC) meets the medulla oblongata of the brain at the foramen magnum. Also, the dura mater- the outer meninx of the SC and brain- is attached to the foramen magnum.
The part of the occipital bone anterior to the foramen magnum --the basilar part-- is a thick medial plate. Two other important occipital structures are the occipital condyles which are smooth bony knobs on either side of the foramen magnum. The weight of the skull is transmitted to the vertebral column by the occipital condyles.
A smaller but important opening into the occipital bone is the hypoglossal canal. The hypoglossal nerve (CN IX) passes through this canal on its way to the nnervate the tongue. In some people, there is also a condylar canal posterior to each occipital condyle.
There are groove and impressions on the occipital bones, in positions where blood vessels and sinuses passed in life. One note -worthy groove is the one left by the venous sinous in life. It trvaelled along the sagittal sinus; branced left and right just before reaching the foramen magnum, then both branches travel around the occipital bone and end at the the jugular foramina.
Work Step by Step
Other Occipital bone structures:
The external occipital protuberances. These are attached to the nuchal ligaments which bind the skull to the vertebral column.
The superior nuchal line is also noteworthy. This is a ridge that extends from the external occipital protuberances to the mastoid process. The superior nuchal line marks the superior border of the neck, and provides points of attachment for several neck and back muscles-- some of which help to keep the head straight. There is also an inferior nuchal line located deeper in the neck. It provides attachment for deeper neck muscles like the longus colli and longus capitis muscles
