[Development of the face in the embryo].

The facial complex and the brain develop separately from a common embryonic structure called ectoblast. The neural crest cells which migrate early on from the neural groove differentiate into facial parenchyma, so that the embryological origin of the face is a neural one. The cephalic pole has a primitive encephalofacial and encephalocervical segmentation with strict topographical correspondence: the nasofrontral and premaxillary structures are related to the anterior brain, whereas the maxillo-mandibular and anterior cervical structures are related to the brainstem and its nerves. Thus the face is a qualitative, quantitative and topographical marker of the central nervous system. At the beginning of the third month the embryo becomes a foetus due to the appearance of the first oral and pharyngeal motor sequences which are dependent upon the neurological development of the brainstem. This sum of embryological knowledge has clinical semiological applications: the face and its functions play the predictive role in the search for associated malformations of the same neural origin (brain, eye, neck, thorax). Such malformations are neurocristopathies.