  We study the preperiodic dynatomic curves $\mathcal{X}\_{n,p}$, the closure
of set of $(c,z)\in \C^2$ such that $z$ is a preperiodic point of $f\_c$ with
preperiod $n$ and period $p$ ($n,p\geq1$). We prove that each
$\mathcal{X}\_{n,p}$ has exactly $d-1$ irreducible components, these components
are all smooth and intersect pairwisely at the singular points of
$\mathcal{X}\_{n,p}$. For each component, we calculate the genus of its
compactification and then give a complete topological description of
$\mathcal{X}\_{n,p}$. We also calculate the Galois group of the defining
polynomial of $\mathcal{X}\_{n,p}$.
