Über das Wachstum des Clivus Röntgenkephalometrische Streckenmessungen an 173 Schädeln

Abstract

This Thesis explores the growth of the Clivus. Not the size of the measured distances were the focus of this study but rather the analysis of the different patterns of skeletal and neural growth. It appeared that several accepted interpetations on the growth of the Clivus may be questioned. Tracings of 173 cephalograms from macerated skulls were made. The occipital part and the sphenoid part of the Clivus were traced, and also the spheno-occipital synchondrosis. The radiographic enlargement, inherent to all rontgen projections, was corrected. The data were checked on outliers. Growth curves were constructed and compared to neural and skeletal population curves. The occipital part of the Clivus has a number of growth zones. The endocranial segment has a neural growth pattern, the pharyngeal segment has a skeletal growth pattern. The growth of the occipital part of the Clivus is almost completed around 12 years of age. Since after birth no major changes occurred in the angulation of the occipital bone, and no obvious differences in lenght occured either, the occipital part of the Clivus cannot be the mechanism that caused flexion of the skull base. The sphenoid part of the Clivus has, as a result of its longer skeletal growth pattern, an influence on the shape of the midface. Its growth continued until adulthood. Simultaneously, the sphenoid part of the Clivus compensated other growth processes of the skull until adulthood. During this growth period a rotation in a dorso-cranial direction can take place. The ossification of the spheno-occipital synchondrosis is not likely to take place in childhood (10-12 years), as is often reported in the literature. The growth of the sphenoid part of the Clivus in the present study clearly continued until adulthood. The ossification of the spheno-occipital synchondrosis started at or around 15 years of age. The growth of the Clivus is very special as it is partly influenced by the brain and partly by the pharynx. The Clivus has two patterns of growth, a neural and a skeletal one. The Clivus does not dominate the surrounding structures, it rather responds to functional stimuli of its environment. There are two compensatory elements: the endocranial part of the occipital bone is a compensatory element for neural growth, the pharyngeal part of the occipital bone and the sphenoid part of the Clivus are compensatory elements for skeletal growth.