[The clivus-sphenoidale angle in children (postnatal flexion of the cranial base)].

The clivus-sphenoidale angle of Landzert expresses the flexion of the cranial base in sagittal direction. In previous studies the same authors verified that the clivus-sphenoidale does not change between the 4th and 9th month of fetal life, with an average value of 127.58 degrees, and that in the adult the angle measures 113.95 degrees. To analyse the variations of the opening of this angle in an age span intermediary to those studied before, 89 human skulls were used belonging to both sexes and varying in age from 2 months extrauterine life to 8 years. The angle was traced and measured upon lateral X-rays taken from all skulls. The distribution of average values according to age is found in tables 1 and 2. For statistical evaluation of data, regression analysis and comparison of averages were used. At hand of the results, it is possible to conclude that: 1) there is a significant reduction of the clivus-sphenoidale angle after birth, that is, from 2 months extrauterine life to 18 months. 2) There is no difference in the average values of the angle between 2 and 8 years of age. 3) Growth of the brain and upright posture seem to be the factors most responsible for the post-natal flexion of the cranial base. 4) The angles show great individual differences in all age groups studied.