Figure 9From: Mathematical model of the anatomy and fibre orientation field of the left ventricle of the heartOn the left, definition of the local coordinate system. O x y z is the global Cartesian coordinate system. The blue axis is normal u to the epicardium; the red axis, latitude v; the dark green axis, longitude w. The colourful surface is the epicardium; the colour depends on altitude z. The curve inside is a fibre as a chord image, the curve does not lie on the epicardium. The normal axis intersects the curve at a point. On the right, definition of the true fibre angle, α; the helix angle, α1; and the longitudinal angle, α2. The thick, dashed line is a tangent to a myofibre segment constructed at the origin of the coordinates. The dashed-and-dotted lines are projections of the myofibre tangent.Back to article page