Fig. (3) The apical rotation in the sense of Aaro-Dahlborn (with the requirement that the chosen line pass the neural groove), in the text we shall denote it.It is the angle between a line passing through the neural groove and also passing through the exterior mid of the sternum, and a line passing through the neural groove and chosen in the sense of Aaro-Dahlborn (in our case manually and we have after manual choice also verified that a certain symmetry with respect to two equidistant points on the lamina, holds true, see main text).