Fig. 3. Detailed ventral view of the internal surface of the Anax junius dorsal thorax at the base of the forewing, showing the location of the basalar muscle apodeme (Ba) and the wing fulcrum (Wf) of the forewing (FW). The distance between these two structures is the muscle apodeme-to-wing fulcrum lever arm length (d₁). All muscle tissue has been removed. Scale bar, 1 mm. A portion of the wing is drawn to orient the reader; this wing is not to scale.