二足起立•歩行訓練がニホンザルの後肢長骨に及ぼす影響

Abstract

We examined morphologies of the femur, tibia and fibula of a Japanese macaque which had been trained for bipedal standing and walking for 8 years through the “Sarumawashi” (traditional Japanese bipedal monkey performance) and compared them with those which we previously described in another monkey trained in the same way for 11 years (Nakatsukasa et al., 1995, Folia Primat. 64: 1-29). This second individual lacked many of the distinctive features which were recognized in the former case: for example, an articular extension of the femoral head onto the neck, a large tubercle for the capsular ligament, very stout femoral and tibial shafts, a broader medial condyle relative to the lateral one, an anteriorly shifted medial tubercle of the intercondylar eminence, and a concavity of the medial aspect of the proximal fibular shaft. On the other hand, a mediolaterally flat femoral shaft, a raised lateral rim of the patellar surface, more concave upper facets of the tibia, and very thick cortical bone with a correspondingly narrow medullary cavity of the femoral staft were shared by both monkeys. Probably, the difference is related to the fact that (1) the present monkey was lighter than the previous one (10kg vs. 18kg) and that (2) it usually stood with the hip joint more extended. Nonetheless, the shared features suggest there is a more or less similar pattern of mechanical stresses (enhanced mediolateral bending of the femur, strong contraction of m. vastus lateralis, greater resultant force at the knee joint) which accompanies bipedal standing in Japanese macaques.