[Contribution to the study of the origin of the phrenic nerve (nervus phrenicus). Apropos of 100 dissections of the cervical plexus].

After recalling the descriptions of classical authors, 100 dissections conducted to the study of the origin of the phrenic nerve (nervus phrenicus). It appears as variable and asymetrical. The presence of an accessory phrenic nerve has been rarely seen. The classical proximal anastomoses of this nerve are inconstant or rare.