Abstract
The myofibrous organization of the gluteal muscle groups (M. gluteus max., M. gluteus med. and M. gluteus min.) was examined. Muscle samples were obtained from 10 adult crab-eating monkeys (6 females and 4 males), and these muscle fibers were differentiated into 3 types : white fibers, red fibers and intermediate fibers by Sudan-Black B staining contrast. The following results were obtained: 1) The muscle weight of the gluteus max. was about one-third that of the gluteus med, and about three times that of the gluteus min. and about one-half compared to lower extremity muscles. Muscles of males were heavier than those of females, but this finding was not related to individual body weights. The same tendency was found in the total number of muscle fibers and their cross-sectional size. 2) The gluteus max, and the gluteus med. had almost the same number of muscle fibers per sq. mm., but fewer than the gluteus min.; the muscle fibers in the gluteal groups were fewer in number as compared to other muscle groups. 3) The ratio of white muscle fibers in gluteus max. was highest (about 60 per cent) among the muscles compared, on the other hand, the average sizes of these fibers were the greatest among the gluteal groups, but smaller than those of biceps femoris. 4) The red fibers in gluteus med. and min. were more than 40 per cent aespectively, and those of the white were about 20 per cent. These two muscle fibers showed a different structure from that of the gluteus max. or other muscles 5) All types of fibers of gluteus max. were the largest, followed by those of the gluteus med., and those of the gluteus min. were smallest among the three gluteal groups. 6) Concerning the sizes of the muscle fibers in the gluteal groups, white had the largest diameter, and showed a wide, low distribution pattern in gluteus max. This tendency was also found in the gluteus med.
