  Let $\mathsf{T}$ be a triangulated category with shift functor $\Sigma \colon
\mathsf{T} \to \mathsf{T}$. Suppose $(\mathsf{A},\mathsf{B})$ is a
co-t-structure with coheart $\mathsf{S} = \Sigma \mathsf{A} \cap \mathsf{B}$
and extended coheart $\mathsf{C} = \Sigma^2 \mathsf{A} \cap \mathsf{B} =
\mathsf{S} * \Sigma \mathsf{S}$, which is an extriangulated category. We show
that there is a bijection between co-t-structures $(\mathsf{A}',\mathsf{B}')$
in $\mathsf{T}$ such that $\mathsf{A} \subseteq \mathsf{A}' \subseteq \Sigma
\mathsf{A}$ and complete cotorsion pairs in the extended coheart $\mathsf{C}$.
In the case that $\mathsf{T}$ is Hom-finite, $\mathbf{k}$-linear and
Krull-Schmidt, we show further that there is a bijection between complete
cotorsion pairs in $\mathsf{C}$ and functorially finite torsion pairs in
$\mathsf{mod}\, \mathsf{S}$.
