title: Posterior fossa measurements. I. The normal size of the posterior fossa.
abstract: The posterior fossa area was defined as that situated below Twining's line while the one above was called the supratentorial area. A ratio has been calculated: Posterior fossa area/Supratentorial area X 100 = posterior fossa ratio. Above 7 years this was (mean) 16.5% +/- 2 and below 7 years 14.0% +/- 4, with the ranges (13.2-20.2) and (9.0 - 19.4), respectively. When the ratio falls below 13% and 9% respectively, this implies therefore a malformation of the posterior fossa, i.e. too flat a space. Two formulas for calculation of the areas mentioned as well as two other ratios are also introduced.
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D012016:Reference Values