Squama occipitalis

Squamous part of occipital bone
Human skull seen from above (parietal bones removed). Squamous part is shown in red.
Occipital bone at birth, seen from below. (Squamous part is top half, portion above foramen magnum, shown in yellow.)
Details
Identifiers
Latin	squama occipitalis
Dorlands /Elsevier	s_21/12753458
TA	A02.1.04.010
FMA	52860
Anatomical terms of bone []

The squamous part of occipital bone, is situated above and behind the foramen magnum, and is curved from above downward and from side to side.

The external surface is convex and presents midway between the summit of the bone and the foramen magnum a prominence, the external occipital protuberance and inion.

Extending lateralward from this on either side are two curved lines, one a little above the other. The upper, often faintly marked, is named the highest nuchal line, and to it the epicranial aponeurosis is attached.

The lower is termed the superior nuchal line. That area of the squamous part, which lies above the highest nuchal lines is named the occipital plane and is covered by the occipitalis muscle. That below, termed the nuchal plane, is rough and irregular for the attachment of several muscles.

From the external occipital protuberance, an often faintly marked ridge or crest, the median nuchal line, descends to the foramen magnum and affords attachment to the nuchal ligament. Running from the middle of this line across either half of the nuchal plane is the inferior nuchal line.

Several muscles are attached to the outer surface of the squamous part, thus the superior nuchal line gives origin to the occipitalis and trapexius muscles, and insertion to the sternocleidomastoid and splenius capitis muscles. Into the surface between the superior and inferior nuchal lines the semispinalis capitis and the obliquus capitis superior are inserted, while the inferior nuchal line and the area below it receive the insertions of the rectus capitis posterior major and minor.