The " frontal bone" is the one which forms the front part of the skull, the part which we call the forehead. It extends about two inches beyond the hairline, where it joins the "parietal bones" which make up the vault of the skull.On the sides it joins the "temporal bones" that is, the small bone on each side, which forms part of the temple and contains the cavity of the ear.
Before the frontal bone joins the temporal bone it bends in sideways and forms a crest down the side of the forehead.You can see and feel that crest as you run your finger up from the outer end of the eyebrow.
And if the expanse of the forehead between the two crests is very wide, you are supposed to be brainy. But it really does not mean that, because if this space is narrow, it may merely mean that the brain is extending itself in another direction instead of from side to side.
The frontal bone also has horizontal ridges right in line with the eyebrows. These ridges mark the frontal sinuses and right underneath these ridges the bone bends under to form, together with other bones, the bony roof of the eye sockets.The frontal bone connects with parts of the upper jaw and other bones of the face
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