Occipital Protrusion Internal

The internal occipital protuberance (protuberantia occipitalis interna, pna, bna, jna) is an unpaired formation located on the inner surface of the occipital bone. It is located at the intersection of the lines connecting the superior and inferior edges of the foramen magnum.

The internal occipital protrusion has the shape of a hemispherical elevation about 1 cm in size. It serves as the attachment point for the superior falx of the cerebellum. In addition, on the internal occipital protrusion there is a fossa for the superior sagittal sinus, in which the latter is divided into two transverse sinuses.

Thus, the occipital protuberance internal plays an important role in the attachment of the cerebellum and the division of the sagittal sinus. Its damage can lead to dysfunction of the cerebellum and venous circulation of the brain.

The occipital protrusion (internal from the Latin protuberantia - protrusion, protus - advanced; occipitale - occipital; interna - internal) is the internal bony protrusion of the cranial vault, located in the area of ​​the foramen magnum, formed by the lower marginal sections of the basilar and both occipital bones. The inner surface of the occipital protrusion, in contact with the walls of the large occipital and transverse foramina, limits them from the outside. The surfaces of the occipital protrusion of the convex part of the sacrum are directly adjacent to it in front and form a protrusion of the sacral bone, the surface of which also has a triangular shape. In other words, the occipital protrusion is formed by connecting the basilar, occipital, forehead, sphenoid and temporal bones of the skull. Through the foramen magnum passes the spinal canal, the dura mater running along its bottom. The sphenooccipital processes (there are eight of them) extend from the base of the occipital bone crest and connect the zygomatic arch with the two occipital and parietal bones.

Continued: The process of development of the occipital internal protrusion is an indirect part of the cranial skeleton. The outer part of this projection is represented by a wide rostral base and a thickened edge that surrounds the foramen magnum (rather than the brachiocephalic foramen). The appearance of the occipital protrusion in higher primates led to a decrease in the strength of the skull in this area, which increased the load on the sphenohyoid joint, but contributed to an increase in head mobility in these animals. This protrusion is formed by the adhesion of the edges of the arches of the greater occipital (and in relation to chimpanzees, the brachycephalic) and foramen magnum and the upper edge of the occipital protuberance, as well as the bones of the base of the skull, as in mammals. The evolutionary history of the nuchal protuberance remains unclear. It probably arose in primates as a result of the influence of the developing occipital bony arch and internal