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Occipital bone
Last reviewed: 23.04.2024
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The occipital bone (os occipitale) is located in the posterior part of the brain area of the skull. In this bone, the basilar part, the two lateral parts and the occipital scales, which surround the large (occipital) foramen (foramen magnum), are distinguished.
The basilar part (pars basilaris) lies in front of the large (occipital) opening. From the front, it joins the body of the sphenoid bone, together with which it forms a clavus. On the lower surface of the basilar part there is an elevation - pharyngeal tuberculum (tuberculum pharyngeum), and along the lateral margin there is a furrow of the lower stony sinus (sulcus sinus petrosi inferioris).
The lateral part (pars lateralis) is paired, behind it passes into the scales of the occipital bone. Bottom on each lateral part there is an ellipsoidal elevation - the occipital condyle (condylus occipitalis), at the base of which is the canalis nerve hypoglossi canal. Behind the condyle is a condylar fossa (fossa condylaris), and on its bottom - a condylar canal opening (canalis condylaris). On the side of the occipital condyle is the jugular incision (incisura jugularis), which, together with the jugular cutting of the pyramid of the temporal bone, forms a jugular opening. Next to the jugular notch on the cerebral surface is a sigmoid sinus groove (sulcus sinus sigmoidei).
Occipital scales (squama occipitalis) - wide, convex to the outside plate, the edges of which are strongly jagged. On the whole skull they connect with the parietal and temporal bones. In the center of the external surface of the scales, the external occipital protrusion (protuberantia occipitalis externa) is visible, from which a slightly outlined upper line (linea nuchae superior) departs in both directions. Down from the protrusion to the large (occipital) opening, the external occipital crest (crista occipitalis externa) passes. From its middle, to the right and to the left, is the lower, different line (hinea nuchae inferior). Over the outer occipital protrusion, the highest line (linea nuchae suprema) is sometimes seen.
On the inner side of the occipital scales is a cruciform elevation (eminentia cruciformis), dividing the cerebral surface of the scales into 4 pits. The center of the cruciform elevation forms the internal occipital protrusion (protuberantia occipitalis interna). To the right and to the left of this projection there is a furrow of the transverse sinus (sulcus sinus transversus). Upward from the protrusion there is a furrow of the superior sagittal sinus (sulcus sinus sagittalis superioris), and downward, to the large (occipital) opening, is the internal occipital crest (crista occipitalis interna).
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