  We derive general covariant coupled equations of QCD describing the
tetraquark in terms of a mix of four-quark states $2q2\bar q$, and two-quark
states $q\bar q$. The coupling of $2q2\bar q$ to $q\bar q$ states is achieved
by a simple contraction of a four-quark $q\bar q$-irreducible Green function
down to a two-quark $q\bar q$ Bethe-Salpeter kernel. The resulting tetraquark
equations are expressed in an exact field theoretic form, and are in agreement
with those obtained previously by consideration of disconnected interactions;
however, despite being more general, they have been derived here in a much
simpler and more transparent way.
