The same authors [3] noted remarkable similarity in length of the fleshy (nontendinous) fibres of the PM fascicles. Within a given specimen, the different fascicles measured within a centimetre in length of one another, and differences between specimens were not large. This, they argued, indicated that the PM was not designed to execute or control flexion of the LS, because the expected far greater arcuate flexion excursions of the upper lumbar vertebrae would require longer fascicles attaching to this