Figures 1 and 2: The wall of the abdomen consists of the external oblique, the transversus, the internal oblique (not shown) and the rectus abdominis, located in-between the fascias of the external oblique and the transversus.
Fig. 3: The lower ribs (8, 9, 10) forming the inferior thoracic border are connected solely by connective tissue to each other. Due to the resulting rather "irregular" structure of the thoraco-abdominal border and in combination with effects produced by the form and state of contraction of the rectus abdominis, the extent of the inclination of the thorax, skin folds and "bumps" of subcutaneous fat tissue, a proper anatomical interpretation is eventually not possible. (This constellation occurs occasionally in elderly men: the muscles mimicking a "heroic" past, the fat tissue "merit and final success" and the skin fold "age and wisdom".)