Fig. 3

Axial (cranial-to-caudal) speed of tissue movement in the spinal column due to a short transient cranial excitation. a At t = 0.005 s from the onset of excitation an initial disturbance with the amplitude of 0.01 m/s (1 cm/s) formed at the cranial end. b At t = 0.025 s the initial disturbance split into three waves which travelled at speeds of 1.5 m/s (wave 1), 7 m/s (wave 2), and 11 m/s (wave 3). The waves generated tissue movement in the range of ±0.01 m/s