[The cranio-spinal joint: apropos of some anomalies]

The occipitocervical region settles down around the rostral extremity of the chorda, from components coming from the parachordal cartilage, the occipital somites and the first cervical somites. The evolution of the ossification points may be defective. This explains the malformations of this region, and their eventual mechanical repercussions. These malformations may be associated with malformations of the nervous system.