Abstract
Myofibrous organization in human hamstrings (m. biceps femoris caput longum ; BFL, caput breve ; BFB, m. semitendinosus ; ST and m. semimembranosus ; SM) were analyzed, and their functions were discussed. Materials were obtained from 17 humans (11 males and 6 females, average 61.4 years) . Sections, which were embedded in celloidin, were stained with hematoxyline and eosin. Results were summarized as follows. Muscle weight of m. biceps femoris was largest and occupied about 40% in hamstrings. SM and ST occupied about 35% and 20%, respectively. Cross-sectional areas in BFL and SM were more than two times as large as those of the other two muscles. The total number of muscle fibers in each muscle was about 200 thousand and the difference between muscles was small. The mean fiber size in the SM, was largest in hamstrings, and the BFL which belongs to the same muscle group had relatively large muscle fibers in human muscles. Fiber sizes in ST and BFB were smaller than those of SM and BFL and belonged to the small muscle fiber groups. The results suggest that SM and BFL are more developed in human hamstrings and have strong functions for knee flexion, and the ST and BFB act to assist or support the knee joint.
