The unpaired occipital bone forms the central part of the back of the skull.

The paired parietal bones contribute to the back of the skull laterally.

The paired temporal  bones make minimal contributions to the back of the skull laterally and inferiorly.


The posterior third of the sagittal suture, between the two parietal bones, is included in a posterior view of the skull.

The lambdoidal suture, between the occipital and parietal bones, can be seen in its entirety.  At each inferolateral extremity, the lambdoidal suture becomes continuous with both the:

Occipitomastoid suture, between the occipital bone and the mastoid part of the temporal bone.

Parietomastoid suture, between the parietal bone and the mastoid part of the temporal bone.


Prominent landmarks and reference points:  

Lambda is the point of intersection of the sagittal and lambdoidal sutures.

The external occipital protuberance is a raised, roughened area on the midline 8-10 cm below lambda.

Inion is the most prominent point of the external protuberance.

The superior nuchal line is the (usually) prominent horizontal ridge running laterally from the external occipital protuberance to the mastoid process of the temporal bone.  It gives attachment to the trapezius muscle (medially) and sternocleidomastoid and splenius capitis muscles (laterally).

The highest nuchal line, a faint ridge of bone above and parallel to the superior nuchal line, gives attachment to the galea aponeurotica medially and the occipital belly of occipitofrontalis muscle laterally.  In many skulls, it cannot be identified.

The mastoid processes of the temporal bones lie at the inferolateral angles of the skull in norma occipitalis.