Abstract
Measurements were made of the total cross-section of the abdominal area at the level of the 4th lumbar vertebral section by X-ray CT image. Cross sectional areas of subcutaneous fat, abdominal cavity (peritoneal and retroperitoneal spaces), vertebra and muscle were measured to assess their differences and correlation by sex, age and body type. Muscles were classified into rectus abdominis, transversus abdominis, obliquus internus abdominis, obliquus externus abdominis, quadratus lumbolum, psoas major, iliocostalis, long-issimus and spinotransversarius. Subjects were 78 healthy adults, 44 males and 34 females, at ages 30 to 70, averaging 52.3 years. The body types were classified into A, C and D by the Rohrer Index, and correlations were assessed by Pearson's product-moment correlation coefficient. The following results were obtained: 1) The actual measurements of subcutaneous fat, abdominal cavity, peritoneal cavity, retroperitoneal space and vertebrae increased with age. 2) There was significant correlation between total cross-sectional area and abdominal cavity (γ=0.81675), or subcutaneous fat (γ=0.84128) . 3) Muscular areas decreased with age in males, except transversus abdominis and spinotransversarius. In females, the muscles decreased with age except the lateral abdominal muscles. 4) There was correlation between total muscular cross-sectional area and each area of abdominis lateralis and iliocostalis in males ; and psoas major, quadratus lumborum and longissimus in females. 5) The propotion of abdominal cavity was largest in all body types in males, and the proportions of subcutaneous fat in A type and abdominal cavity in C and D types were largest in females. 6) In both sexes, the proportions of each muscle increased in the order of A, C and D type, but there was no correlation between Rohrer Index and muscles.
