[Intramedullary topography of the motor neurons of the brachial plexus of the rat. Preliminary study].

The exact localisation of the motor pools of anterior horn providing the different nerves of the brachial plexus remains unclear. The data obtained have been furnished by different methods: Nissl methods furnish cytoarchitectonic data -- Golgi methods furnish dendro-architectonic data. The topographical data were obtained by the chromatolytic modifications of the moto-neurons after a peripheral nerve injury. The recently used method of the retrograde transport of HRP permits to get information about the exact localisation and the dendritic extent of the neurons of a motor pool related to a particular nerve. We have studied the localisation of the nerves of the brachial plexus in the cervical enlargement of the spinal cord. We have determined the exact extent of the different motor pools in relation to each nerve. It seems that two different regions may be recognized in the anterior horn: a ventro lateral one in relation with the girdle muscles and a dorso lateral region related with the more distal muscles of the anterior limb.