A crucial question at the center of corporate governance theories and of the literature on social networks alike is the sense of empower of prestige, or influence on the actors of a social network. This paper approaches the possibility of measuring this influence by detecting key individuals who support network dynamics. By means of a study conducted on a sample of CAC 40 directors, it will be shown that the most influential elements are not necessarily the best placed at the beginning. Contrary to all expectations, a dynamics of influence is based on criteria of indispensability to the network that will be presented as an example.