Online Encyclopedia

TIE SKULL FROM ABOVE (norma verticalis)

Online Encyclopedia
Originally appearing in Volume V25, Page 196 of the 1911 Encyclopedia Britannica.
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TIE SKULL FROM ABOVE (norma verticalis). When looked at from above the frontal bone is seen forming the anterior part of the vertex and articulating with the two parietals posteriorly by a nearly transverse serrated suture (coronal suture). Running back from the middle of this is the median sagittal suture extending as far as the lambda on the norma occipitalis. The point where the sagittal and coronal sutures join is the bregma, the site of the lozenge-shaped anterior fontanelle in the infant's skull, but this closes during the second year of life. Small ossicles called Wormian bones are often found in the cranial sutures, and one of these (the interfrontal or os anti-epilepticum) is sometimes found at the bregma. About two-thirds of the way back the sagittal suture becomes less serrated and on each side of it the, small parietal foramen may be seen. This only transmits a small emissary vein (see VEINS) in the adult, but, as will be seen later, is of considerable morphological interest. As middle life is reached the cranial sutures tend to become obliterated and the bones can no longer be separated; this fusion begins at the places where the sutures are least deeply serrated, and as a rule the sagittal suture disappears between the two parietal foramina between thirty and forty years of age.
End of Article: TIE SKULL FROM ABOVE (norma verticalis)
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