Study on the sites of nerve entrance in innervation of skeletal muscles is important in the field of anatomy, histology, physiology and pathology, and since 19 th century, many researchers have been engaged in the macroscopical investigations on nerve entrance of muscles. However, their results were not always precise, because they seemed to employ macroscopical methods without measuring a length of muscles and a distance between origin and insertion of various muscles in thigh
In this paper, first, the muscle length was determined by measuring the distance between origin and insertion directly (designated here as“direct method”) or by measuring the length of muscles along their course (designated here as“indirect method”) by scale. Concomitantly, the number and diameter of major innervated nerves of each muscle were also examined. Next, the distance between nerve entrance and the origin of 9 thigh muscles were carefully measured. The difference of the values obtained referring to sex and age was also surveyed. Adding to it, the correlation between the sites of nerve entrance and that of muscle belly was also studied. The details of respite were ae fn11imr
1) The values of muscle length obtained from direct and indirect methods were compared in paying attention to each belly of muscles. 10 specimens in M, sartorius and M, rectus femoris were used for it. The difference of values between direct and indirect methods was negligible, that is, only 1 to 2.5% difference are there respectively.
2) The number of major nerve entering into each muscle were one or two. The number of major nerves and their diameter (parenthesized) of 21 specimens were as follow; one (1.6 mm) for M, sartorius, two (1.6 mm) for M. rectus femoris, two (2.4 mm) for M, vastus medialis and M. vastus lateralis, one (1.8 mm) for M, gracilis, one (1.7 mm) for M. adductor longus, two (2.4 mm) for M, biceps femoris (caput longum), two (2.5 mm) for M, semitendinosus and two (2.6 mm) for M, semimembranosus.
3) Using 41 specimens, the sites of nerve entrance where one or two major nerves were entered into thigh muscles were measured with the indirect methods. The sites of nerve entrance were indicated with the ratio calculated from the formula described in Result-C. Their sites were 21.4% from the origin for M, sartorius, 14.9% and 25.5% for M. rectus femoris, 22.6% and 39.3% for M. vastus medialis, 17.0% and 35.1% for M, vastus lateralis, 22.3% for M, gracilis, 44.7% for M, adductor longus, 22.1% and 38.6% for M. biceps femoris (caput longum), 15.5% and 43.0% for M. semitendinosus, and 46.7% and 61.7% for M, semimembranosus. However, the difference in the sites of nerve entrance related to sex and age was hardly in those specimens.
4) The difference between the sites of nerve entrance (either one or two) and muscle belly was evident in M, vastus medialis and M, adductor longus. The values of deviation in M. vastus medialis and M. adductor longus stood about at 20%. The difference of the other muscles (M. sartorius, M, rectus femoris, M, vastus lateralis, M, gracilis, M, biceps femoris; caput longum, M, semitendinosus, M, semimembranosus) stood at 3 to 7%.
5) Some discussions were devoted to the relationship of sites between nerve entrance in anatomy and motor point in kinesiology.