  In this paper we compute the limit distributions of the numbers of
hairpin-loops, interior-loops and bulges in k-noncrossing RNA structures. The
latter are coarse grained RNA structures allowing for cross-serial
interactions, subject to the constraint that there are at most k-1 mutually
crossing arcs in the diagram representation of the molecule. We prove central
limit theorems by means of studying the corresponding bivariate generating
functions. These generating functions are obtained by symbolic inflation of
Ik5-shapes.
