Anatomically realistic and biophysically based computational models of the heart have provided valuable insights into cardiac function in health and disease. Nevertheless, these models typically use a "black-box" approach to describe the cellular level processes that underlie the heart beat. We are developing techniques to stochastically generate three-dimensional models of mammalian ventricular myocytes that exhibit salient characteristics of the spatial organisation of key cellular organelles in cardiac cell excitation and contraction. Such anatomically detailed models will facilitate a deeper understanding of cardiac function at multiple scales. This paper presents an important first step towards understanding and modelling the spatial distribution of two key organelles in cardiac cell contraction - myofibrils and mitochondria. The sarcolemma, myofibrils and mitochondria were segmented from transmission electron micrographs of ventricular cells from a healthy wistar rat. The centroids of the myofibrils and mitochondria were calculated, and various spatial statistical techniques for characterising the centroid distribution and inter-point interactions were investigated and implemented using the R spatstat package. Techniques for modelling the observed spatial patterns were also investigated, and preliminary results indicate that the Strauss Hard-core model best captures the interaction observed. We intend to confirm these results with larger sample of cells.