Fig. 1. Schematic representation of a basalar muscle and its third order lever system. FWf indicates the position of the wing fulcrum, FW represents forewing length and Ba indicates the position of the apodeme of the basalar muscle. The basalar muscle (yellow) produces force F_dyn, which is then transmitted through d₁, the distance between the basalar apodeme and wing fulcrum, and d₂, the second moment of wing area where the mean aerodynamic force acts.