[The inborn cervical block vertebra. Part I: morphology and localisation (author's transl)].

Reviewing the X-rays of 72 patients with 77 congenital block vertebrae of the spine a morphological classification of this deformity of the spine is given as well as a description of radiological signs. Four different basic types are found according to the degree of deformity. Definition and pathogenesis of the congenital block vertebra of the cervical spine are separated from acquired synostoses of vertebrae. The frequency of anatomical localisations is described as well as differences due to sex.