In this paper, we describe a method for automatic construction of arbitrary number of muscle fibres in the volume of a muscle represented by its surface mesh. The method is based on an iterative, slice-by-slice, morphing of predefined fibres template into the muscle volume. Our experiments with muscles of thighs and pelvis show that in most cases, the method produces realistic fibres. For some muscles, especially, those with large attachment areas, some imperfections are observable; however, results are acceptable anyway. As our sequential VTK-based C++ implementation is capable of producing 128 fine fibres within a muscle of 10K triangles in 380 ms on commodity hardware (Intel i7), the method is suitable for interactive educational medical software. We believe that it could also be used in clinical biomechanical applications to extract information on the current muscle lever arm and fibre path.