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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

Early-stage development of the annular ligament of the radius. A 10-week fetus (crown-rump length, 55 mm). Cross-sections of the elbow. Hematoxylin and eosin staining (A and C) and silver staining (B). Panel (A) (panel C) is the most distal (proximal) side of the figure. Intervals between panels are 0.1 mm (A-B, B-C). The supinator muscle originates from a ridge (open star) of the ulna via a long tendon (arrowheads in A and B). At levels between (B) and (C), this tendon is continuous with the primitive annular ligament of the radius (arrows in C). Outside the tendon and ligament, there is an intermuscular fascia (black stars) connecting the extensor carpi radialis (ECR) and anconeus muscles: this fascia is much thinner than the primitive annular ligament. BR, brachioradialis muscle. Scale bar in (A)=1 mm (A-C).
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Figure 1: Early-stage development of the annular ligament of the radius. A 10-week fetus (crown-rump length, 55 mm). Cross-sections of the elbow. Hematoxylin and eosin staining (A and C) and silver staining (B). Panel (A) (panel C) is the most distal (proximal) side of the figure. Intervals between panels are 0.1 mm (A-B, B-C). The supinator muscle originates from a ridge (open star) of the ulna via a long tendon (arrowheads in A and B). At levels between (B) and (C), this tendon is continuous with the primitive annular ligament of the radius (arrows in C). Outside the tendon and ligament, there is an intermuscular fascia (black stars) connecting the extensor carpi radialis (ECR) and anconeus muscles: this fascia is much thinner than the primitive annular ligament. BR, brachioradialis muscle. Scale bar in (A)=1 mm (A-C).

Mentions: At 10 weeks, although it was still composed of loose fibrous tissue, the ANL was already evident in the deep side of the anconeus (Fig. 1). The supinator muscle originated from a ridge of the cartilagenous ulna via a long distinct tendon (Fig. 1A, B). Notably, at a more proximal level, the supinator tendon became thicker and was continuous with the ANL. In the superficial side of the tendon and ligament, an intermuscular fascia extended between the extensor carpi radialis and anconeus muscles: this fascia was much thinner than the ANL. However, at 12-15 weeks, the intermuscular fascia became thick, and at 18 weeks, it was much thicker than the ANL (Fig. 2). Thus, near the origin from the ulna, the supinator muscle fibers were sandwiched by the ANL and the intermuscular fascia or band (Fig. 2B, D). At 18 weeks, the supinator tendon was tightly attached to the ANL and the tendon was difficult to discriminate from the ligament. Parts of the supinator muscle were still attached to the head of the radius. We observed several thick muscle fibers with multiple nuclei in the supinator along the head of the radius (Fig. 2F). At 22 weeks, both the ANL and supinator muscle were well developed. The thick and tight ANL contained several long muscle fibers originating from the supinator muscle (data not shown).


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)

Early-stage development of the annular ligament of the radius. A 10-week fetus (crown-rump length, 55 mm). Cross-sections of the elbow. Hematoxylin and eosin staining (A and C) and silver staining (B). Panel (A) (panel C) is the most distal (proximal) side of the figure. Intervals between panels are 0.1 mm (A-B, B-C). The supinator muscle originates from a ridge (open star) of the ulna via a long tendon (arrowheads in A and B). At levels between (B) and (C), this tendon is continuous with the primitive annular ligament of the radius (arrows in C). Outside the tendon and ligament, there is an intermuscular fascia (black stars) connecting the extensor carpi radialis (ECR) and anconeus muscles: this fascia is much thinner than the primitive annular ligament. BR, brachioradialis muscle. Scale bar in (A)=1 mm (A-C).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3713279&req=5

Figure 1: Early-stage development of the annular ligament of the radius. A 10-week fetus (crown-rump length, 55 mm). Cross-sections of the elbow. Hematoxylin and eosin staining (A and C) and silver staining (B). Panel (A) (panel C) is the most distal (proximal) side of the figure. Intervals between panels are 0.1 mm (A-B, B-C). The supinator muscle originates from a ridge (open star) of the ulna via a long tendon (arrowheads in A and B). At levels between (B) and (C), this tendon is continuous with the primitive annular ligament of the radius (arrows in C). Outside the tendon and ligament, there is an intermuscular fascia (black stars) connecting the extensor carpi radialis (ECR) and anconeus muscles: this fascia is much thinner than the primitive annular ligament. BR, brachioradialis muscle. Scale bar in (A)=1 mm (A-C).
Mentions: At 10 weeks, although it was still composed of loose fibrous tissue, the ANL was already evident in the deep side of the anconeus (Fig. 1). The supinator muscle originated from a ridge of the cartilagenous ulna via a long distinct tendon (Fig. 1A, B). Notably, at a more proximal level, the supinator tendon became thicker and was continuous with the ANL. In the superficial side of the tendon and ligament, an intermuscular fascia extended between the extensor carpi radialis and anconeus muscles: this fascia was much thinner than the ANL. However, at 12-15 weeks, the intermuscular fascia became thick, and at 18 weeks, it was much thicker than the ANL (Fig. 2). Thus, near the origin from the ulna, the supinator muscle fibers were sandwiched by the ANL and the intermuscular fascia or band (Fig. 2B, D). At 18 weeks, the supinator tendon was tightly attached to the ANL and the tendon was difficult to discriminate from the ligament. Parts of the supinator muscle were still attached to the head of the radius. We observed several thick muscle fibers with multiple nuclei in the supinator along the head of the radius (Fig. 2F). At 22 weeks, both the ANL and supinator muscle were well developed. The thick and tight ANL contained several long muscle fibers originating from the supinator muscle (data not shown).

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