Myofibrous Organization in Human Abdominal Muscles

Abstract

Myofibrous organization was studied in the abdominal muscles (rectus abdominis: RA, obliquus externus: OE, obliquus internus: OI, trans-versus abdominis: TA and quadratus lumborum: QL) from 14 cadavers (8 males and 6 females, aged 46-90 years) to analyze functions of the abdominal muscles. In RA, the fiber size was approximately equal to that of OE and TA and belonged in the moderate muscle fiber group of human muscle. The fiber density in RA was the lowest among the abdominal muscles. In the lateral abdominal muscles, OI, which had the greatest thickness in the muscle layer and the largest muscle fibers of the three muscles, was most predominant, and was followed by OE and TA. QL had the largest muscle fibers among the abdominal muscles which belong in the group of relatively large human muscles. Based on the features of the myofibrous organization, these results suggested functional differences among the abdominal muscles, especially between OE and OI.