  We describe an ultra-compact ($\sim 10$ cm$^3$ physics package) inertial
sensor based on atomic matter waves that are guided within an optical lattice
during almost the entire interferometer cycle. We demonstrate large momentum
transfer (LMT) of up to 8$\hbar k$ photon momentum with a combination of Bragg
pulses and Bloch oscillations with scalability to larger numbers of photons.
Between momentum transfer steps, we maintain the atoms in a co-moving optical
lattice waveguide so that the atoms are in free space only during the Bragg
pulses. Our guided matter wave approach paves the way for atomic inertial
sensing in dynamic environments in which untrapped atoms would otherwise
quickly collide with the walls of a miniature chamber.
