MacLane-Vaqui\'e chains of valuations on a polynomial ring

Let $(K,v)$ be a valued field. We review some results of MacLane and Vaqui'e on extensions of $v$ to valuations on the polynomial ring $K[x]$. We introduce certain MacLane-Vaqui'e chains of residually transcendental valuations, and we prove that every valuation $\mu$ on $K[x]$ is a limit of a finite or countably infinite MacLane-Vaqui'e chain. This chain underlying $\mu$ is essentially unique and contains arithmetic data yielding an explicit description of the graded algebra of $\mu$ as an algebra over the graded algebra of $v$.