The Occipital Bone

The occipital bone consists of a large squamous, or flattened portion separated from a small thick basal portion by the foramen magnum on either side of which is a left or right occipital condyle. The occipital condyles articulate with the first cervical vertebrae (the atlas). Externally, the squamous portion of the bone possesses superior, middle, and inferior nuchal lines to which the muscles at the back of the neck are attached. The external occipital protuberance lies on the superior nuchal line in the mid-sagittal plain. Lateral to each occipital condyle are the condylar fossae and foramen while the hypoglossal canal is medial to them.

Internally, are the sagittal and transverse sulci, or grooves which converge at the confluence of sinuses. A single internal occipital protuberance or cruciform eminence is also found in this area. Running inferior from the eminence to the foramen magnum is the internal occipital crest which separates the cerebellar fossae. The transverse sulci assist in directing the developing jugular vein to the jugular notch on either side of the basilar portion of the occipital.

To view a QuickTime VR movie of the occipital bone click

The occipital touches, or articulates with, the following bones:

• Parietals
• Temporals
• Sphenoid
• Atlas - The atlas is not part of the skull. It is the first of the seven cervical vertebrae and the one upon which the base of the skull sits. It is the bone around which the skull rotates, hence the name "atlas."