In this paper, we present a physics-based deformable model framework for the quantification of shape and motion parameters of the Left Anterior Descending (LAD) coronary artery in the heart's local frame of reference. We define the long-axis of the heart as the local frame of reference. The shape of the LAD is modeled as a parametric curved axis with Frenet-Serret frame. The motion of the LAD (due to heart motion) is modeled as a composite of primitive shape-motion components: 1) longitudinal elongation, 2) radial displacement, and 3) twist with respect to the heart's local frame of reference. The three-dimensional shape-motion components are parameterized along the LAD's length. Results from simulated data and three asymptomatic subjects' Electron Beam Computed Tomography (EBCT) data are in agreement with the expected physiological trends.