Influence of developing ligaments on the muscles in contact with them: a study of the annular ligament of the radius and the sacrospinous ligament in mid-term human fetuses

Abstract

The supinator muscle originates from the annular ligament of the radius, and the muscle fibers and ligament take a similar winding course. Likewise, the coccygeus muscle and the sacrospinous ligament are attached together, and show a similar fiber orientation. During dissection of adult cadavers for our educational curriculum, we had the impression that these ligaments grow in combination with degeneration of parts of the muscles. In histological sections of 25 human fetuses at 10-32 weeks of gestation, we found that the proximal parts of the supinator muscle were embedded in collagenous tissue when the developing annular ligament of the radius joined the thick intermuscular connecting band extending between the extensor carpi radialis and anconeus muscles at 18-22 weeks of gestation, and the anterior parts of the coccygeus muscle were surrounded by collagenous tissue when the intramuscular tendon became the sacrospinous ligament at 28-32 weeks. Parts of these two muscles each seemed to provide a mold for the ligament, and finally became involved with it. This may be the first report to indicate that a growing ligament has potential to injure parts of the "mother muscle," and that this process may be involved in the initial development of the ligament.

Foetal development of the human gluteus maximus muscle with special reference to its fascial insertion

“…The highly developed GMX appears to require a new strong origin from the sacrotuberous ligament. In fact, the ligament develops in the late foetal stage, in contrast to the sacrospinous ligament [6]. An increase in the volume of the foetal gluteal muscles might be the most essential feature of this evolutionary transition.…”

A Systematic Review of the Normal Sacroiliac Joint Anatomy and Adjacent Tissues for Pain Physicians

“…The dorsal aspect of the piriformis muscle is continuous with the STL, and the fibers attach directly to the ventral part of the STL (115). Furthermore, in the fetus, thick collagen fibers corresponding to the final SSL were found in the posteroinferior margin of the coccygeus muscle after 31 weeks in utero (126).…”

“…Various muscles cross the SIJ, but none are thought to directly impact it (64,122). Myofascial structures that may influence the joint include: the BF muscle, the coccygeus muscle, the ES muscles, the GMax muscle, the multifidus muscle, the deep pelvic fascia, the piriformis muscle, the quadratus lumborum muscle, the semimembranosus (SemiM) muscle, the semitendinosus (SemiT) muscle and the TLF (4,7,12,26,63,70,(123)(124)(125)(126)(127)(128). Additionally, the gluteus medius muscle, the latissimus dorsi muscle, the psoas (major and minor) muscles and the transversus abdominis muscles have been mentioned to attach to the TLF in Harrison et al (122).…”

Oblique cord (chorda obliqua) of the forearm and muscle-associated fibrous tissues at and around the elbow joint: a study of human foetal specimens

“…The proximal parts of the FDP and FPL in foetuses were likely later replaced by collagenous tissues, resulting in a specific type of intermuscular septum i.e., the oblique cord. A muscle-ligament transition from the supinator to the annular ligament of the radius likely occurred very near the cord [10]. In adults, musculofibrous tissues from the supinator muscle belly often join the oblique cord [14].…”