Abstract
The features of the muscles of the abdomen, the Obliquus externus abdominis (Obl. ext.), the Obliquus internus abdominis (Obl. int.), the Transversus abdominis (Transv.), and the Rectus abdominis (Rectus), were investigated in 10 six-month fetuses and 10 seven-month fetuses.
The results were as follows:
1) Features of the muscles of the abdomen
(i) Origin or insertion :
Obl. ext. From the 5th costa to the 12th costa 35 sides (87.5%)
Obl. int. From the 10th costa to the 12th costa 40 sides (100.0%)
Transv. From the 6th costa to the 12th costa 36 sides (90.0%)
Rectus From the 5 th costa to the 7th costa 24 sides (60.0%)
(ii) Number of the tendinous intersections
Three 25 sides (62.5%)
Two 15 sides (37.5%)
(iii) Length of the arcuata lines
Six-month fetus mean 0.7 cm (min. 0.6-max. 0.9cm)
Seven-month fetus mean 1.0 cm (min. 0.8-max. 1.3cm)
(iv) Length of the semilunar lines
Six-month fetus mean 5.5 cm (min. 4.4-max. 6.7cm)
Seven-month fetus mean 6.3 cm (min. 5.6-max. 8.0cm)
2) Dimensions of the muscles of the abdomen
(i) Six-month fetus
Obl. ext. mean 7.2 cm2 (min. 5.5-max. 11.3cm2)
Obl. int. mean 3.8 cm2 (min. 2.3-max. 6.0cm2)
Transv. mean 5-2 cm2 (min. 3.3-max. 8.4cm2)
Rectus mean 4.7 cm2 (min. 3.3-max. 6.3cm2)
(ii) Seven-month fetus
Obl. ext. mean 12.3cm2 (min. 8.4-max. 18.0cm2)
Obl. int. mean 7.4 cm2 (min. 3.9-max. 10.5cm2)
Transv. mean 8.8 cm2 (min. 6.3-max. 12.6cm2)
Rectus. mean 8.3 cm2 (min. 6.0-max. 11.2 cm2)
3) Weight of the muscles of the abdomen
(i) Six-month fetus
Obl. ext. mean 0.8g (min. 0.5-max. 1.2g)
Obl. int. mean 0.5 g (min. 0.4-max. 0.7g)
Transv. mean 0.5 g (min. 0.4-max. 0.6g)
Rectus mean 0.6 g (min. 0.3-max. 0.9g)
(ii) Seven-month fetus
Obl. ext. mean 1.5g (min. 0.9-max. 2.3g)
Obl. int. mean 1.2g (min. 0.7-max. 2.0g)
Transv. mean 1.0g (min. 0.3-max. 1.4g)
Rectus mean 1.3g (min. 0.8-max. 2.0g)
4) Laterality
The means of the dimensions and weight of each muscle showed no statistically significant lateralities through the T-test.
