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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.

Hayashi S, Kim JH, Rodriguez-Vazquez JF, Murakami G, Fukuzawa Y, Asamoto K, Nakano T - Anat Cell Biol (2013)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Medical Education Center, Aichi Medical University School of Medicine, Aichi, Japan. ; Department of Anatomy, Aichi Medical University School of Medicine, Aichi, Japan.

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.

No MeSH data available.


Related in: MedlinePlus

Sacrospinous ligament appearing along the inferior margin of the coccygeus muscle. A 31-week fetus (crown-rump length, 255 mm). Sagittal sections of the pelvis. hematoxylin and eosain staining. Panel (A) (panel D) is the most medial (lateral) side of the figure. Intervals between panels are 1.2 mm (A-B), 1.6 mm (B-C), and 0.4 mm (C-D). Panel (E) is a higher-magnification view of the square in panel (D). The left-hand side of (A-C) corresponds to the anterior side of the pelvis, while that of panel (D) corresponds to the inferior side. The intramuscular tendon of the coccygeus muscle (arrows in C) is connected with the developing sacrotuberous ligament (STL). The sacrospinous ligament appears along the inferior margin of the coccygeus muscle (filled stars in D) and contains irregularly arrayed muscle fibers (open stars in E). LA, levator ani muscle; OI, obturator internus muscle. Scale bars=2 mm (A-D), 0.1 mm (E).
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Figure 5: Sacrospinous ligament appearing along the inferior margin of the coccygeus muscle. A 31-week fetus (crown-rump length, 255 mm). Sagittal sections of the pelvis. hematoxylin and eosain staining. Panel (A) (panel D) is the most medial (lateral) side of the figure. Intervals between panels are 1.2 mm (A-B), 1.6 mm (B-C), and 0.4 mm (C-D). Panel (E) is a higher-magnification view of the square in panel (D). The left-hand side of (A-C) corresponds to the anterior side of the pelvis, while that of panel (D) corresponds to the inferior side. The intramuscular tendon of the coccygeus muscle (arrows in C) is connected with the developing sacrotuberous ligament (STL). The sacrospinous ligament appears along the inferior margin of the coccygeus muscle (filled stars in D) and contains irregularly arrayed muscle fibers (open stars in E). LA, levator ani muscle; OI, obturator internus muscle. Scale bars=2 mm (A-D), 0.1 mm (E).

Mentions: At 18 weeks, the SSL was identified as a loose fibrous band that appeared to be an insertion tendon of the coccygeus muscle (Fig. 3). However, some muscle fibers of the coccygeus were already embedded in the loose ligament (Fig. 3C, D). The primitive ligament was not yet connected with the sacrum. The sacrococcygeus posterior muscle [16] appeared to have already united with the coccygeus. At 28 weeks, the obturator internus muscle was very thick and extended more posteriorly than the tendon curving along the ischium. The tendinous arch of the levator ani muscle was long and loose. An intramuscular tendon was evident in the coccygeus muscle, and this extended outside the muscle along the inferior aspect (Fig. 4). Near the tendon, some muscle fibers of the coccygeus were much thicker than others and had lost their myotube morphology (Fig. 4E). The sacrotuberous ligament was well developed near the ischial tuberosity at 28 weeks, but appeared to connect between the gluteus maximus muscle and the tuberosity (Fig. 4D). At 31 weeks, the intramuscular tendon of the coccygeus muscle was connected with the growing sacrotuberous ligament (Fig. 5). In the posteroinferior margin of the coccygeus muscle, we found a thick bundle of collagenous fibers, which corresponded to the final SSL (Fig. 5D) in view of its topographical relationship with the sacrotuberous ligament. The SSL contained irregularly arrayed muscle fibers (Fig. 5E).


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.

Hayashi S, Kim JH, Rodriguez-Vazquez JF, Murakami G, Fukuzawa Y, Asamoto K, Nakano T - Anat Cell Biol (2013)

Sacrospinous ligament appearing along the inferior margin of the coccygeus muscle. A 31-week fetus (crown-rump length, 255 mm). Sagittal sections of the pelvis. hematoxylin and eosain staining. Panel (A) (panel D) is the most medial (lateral) side of the figure. Intervals between panels are 1.2 mm (A-B), 1.6 mm (B-C), and 0.4 mm (C-D). Panel (E) is a higher-magnification view of the square in panel (D). The left-hand side of (A-C) corresponds to the anterior side of the pelvis, while that of panel (D) corresponds to the inferior side. The intramuscular tendon of the coccygeus muscle (arrows in C) is connected with the developing sacrotuberous ligament (STL). The sacrospinous ligament appears along the inferior margin of the coccygeus muscle (filled stars in D) and contains irregularly arrayed muscle fibers (open stars in E). LA, levator ani muscle; OI, obturator internus muscle. Scale bars=2 mm (A-D), 0.1 mm (E).
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Related In: Results  -  Collection

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Figure 5: Sacrospinous ligament appearing along the inferior margin of the coccygeus muscle. A 31-week fetus (crown-rump length, 255 mm). Sagittal sections of the pelvis. hematoxylin and eosain staining. Panel (A) (panel D) is the most medial (lateral) side of the figure. Intervals between panels are 1.2 mm (A-B), 1.6 mm (B-C), and 0.4 mm (C-D). Panel (E) is a higher-magnification view of the square in panel (D). The left-hand side of (A-C) corresponds to the anterior side of the pelvis, while that of panel (D) corresponds to the inferior side. The intramuscular tendon of the coccygeus muscle (arrows in C) is connected with the developing sacrotuberous ligament (STL). The sacrospinous ligament appears along the inferior margin of the coccygeus muscle (filled stars in D) and contains irregularly arrayed muscle fibers (open stars in E). LA, levator ani muscle; OI, obturator internus muscle. Scale bars=2 mm (A-D), 0.1 mm (E).
Mentions: At 18 weeks, the SSL was identified as a loose fibrous band that appeared to be an insertion tendon of the coccygeus muscle (Fig. 3). However, some muscle fibers of the coccygeus were already embedded in the loose ligament (Fig. 3C, D). The primitive ligament was not yet connected with the sacrum. The sacrococcygeus posterior muscle [16] appeared to have already united with the coccygeus. At 28 weeks, the obturator internus muscle was very thick and extended more posteriorly than the tendon curving along the ischium. The tendinous arch of the levator ani muscle was long and loose. An intramuscular tendon was evident in the coccygeus muscle, and this extended outside the muscle along the inferior aspect (Fig. 4). Near the tendon, some muscle fibers of the coccygeus were much thicker than others and had lost their myotube morphology (Fig. 4E). The sacrotuberous ligament was well developed near the ischial tuberosity at 28 weeks, but appeared to connect between the gluteus maximus muscle and the tuberosity (Fig. 4D). At 31 weeks, the intramuscular tendon of the coccygeus muscle was connected with the growing sacrotuberous ligament (Fig. 5). In the posteroinferior margin of the coccygeus muscle, we found a thick bundle of collagenous fibers, which corresponded to the final SSL (Fig. 5D) in view of its topographical relationship with the sacrotuberous ligament. The SSL contained irregularly arrayed muscle fibers (Fig. 5E).

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Medical Education Center, Aichi Medical University School of Medicine, Aichi, Japan. ; Department of Anatomy, Aichi Medical University School of Medicine, Aichi, Japan.

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.

No MeSH data available.


Related in: MedlinePlus