Fig. 6. Actions of the extensor and flexor tibiae muscles during kicking and
jumping. (A) A kick by a restrained female. The flexor muscle is active first
and moves the tibia to a flexed position. The flexor and extensor muscles then
co-contract. The large spikes in the extensor have been distorted by the
amplifier. The flexor muscle spikes stop just before the tibia extends
rapidly, while those of the extensor continue for another 15-20 ms. (B) A jump
by an unrestrained female. The pattern of muscle action is similar to that
during kicking, with a period of co-contraction followed by cessation of
flexor activity before the tibia extends and the insect takes off. The jump
propels the insect beyond the limits of the tibial movement detector so that
the movement trace is lost.
