  We examine the internal geometry of a Kleinian surface group and its
relations to the asymptotic geometry of its ends, using the combinatorial
structure of the complex of curves on the surface. Our main results give
necessary conditions for the Kleinian group to have `bounded geometry' (lower
bounds on injectivity radius) in terms of a sequence of coefficients
(subsurface projections) computed using the ending invariants of the group and
the complex of curves.
  These results are directly analogous to those obtained in the case of
punctured-torus surface groups. In that setting the ending invariants are
points in the closed unit disk and the coefficients are closely related to
classical continued-fraction coefficients. The estimates obtained play an
essential role in the solution of Thurston's ending lamination conjecture in
that case.
