68-4

36/136

Data analyses The morphometric and calculated values including PCSA were analyzed by one-way analysis of vari-ance and multiple comparison tests (Tukey’s honest significant difference test, Bonferroni). All values are presented as mean ± standard deviation. Statistical analyses were conducted using the IBM SPSS version 23 (IBM Corporation, Armonk, NY, USA), and the significance level for all tests was set at P<0.05.Anatomy of the iliopsoas and rectus femorisThe PM, with two heads arising from two different origins, originated as the superficial head from the intervertebral discs between T12 and L4 and the adjacent rims of the vertebral bodies, and as the underlying head from the costal process of L1-L5 and the twelfth rib, and converged to form the insertion tendon ending on the lesser trochanter of the femur. The IL, originating from the iliac fossa and the anterior inferior iliac spine, terminated mainly via the insertion tendon and partly directly without the tendon on the lesser trochanter. The psoas minor, originating from the vertebral body of 356Figure 2　 Photographs of isolated muscle specimens of the iliopsoas and rectus femoris in the left-side and superficial views.PMi, psoas minor; PMa, psoas major; IL, iliacus; RF, rectus femorisT12 and L1 and inserting onto the iliac fascia at the iliopubic ramus, contributed little to the flexion of the hip joint. The rectus femoris originated at the anterior inferior iliac spine and the upper part of the acetabulum and inserted onto the tibial tuber-osity through the patella.The PCSA of the iliopsoas (PM, IL) and the rectus femoris was estimated from the morpho-metric data obtained from the isolated muscle spec-imens (Figure 2). The muscle FL of the iliopsoas (PM: 13.76 cm, IL: 11.10 cm) was longer than that of the rectus femoris (8.04 cm) (P<0.01). The PCSA of the rectus femoris (10.88 cm2) was larger than that of the PM (5.45 cm2) (P<0.05). The PCSA of the iliopsoas was comparable with that of the rectus femoris (Table 1).MAL under different hip joint angles in the sagittal planeIn the hip extension position (0°), the MAL of the rectus femoris (35.0 ± 4.0 mm) was larger than that of PM and IL (22.9 ± 1.9 mm). When the hip joint was flexed, the MAL of the rectus femoris increased gradually in mild flexions to achieve a maximal value at 40° (50.4 mm) and decreased Results