The lumbar fossa is medically a sacral depression, a fossa-like depression formed by the sagging of the skin at the location of the projection of the sacral depression on the body surface.
The sacrum is composed of five sacral vertebrae fused to each other, divided into the base of the sacrum, the lateral part of the sacrum, the tip of the sacrum, the pelvic surface of the sacrum and the dorsal surface of the sacrum, which is inverted triangular in shape. The lumbar fossa is the depression of the skin formed by the depression of the dorsal surface of the sacrum.
In general, the shape of the sacrum is essentially the same in all people, except for gender differences. However, the formation of the epidermal depression, or lumbar fossa, is also related to the amount of subcutaneous fat. The less subcutaneous fat there is, the more pronounced the depression is. The more subcutaneous fat there is, the less pronounced the dimple is.
The presence or absence of waist hollows is a normal phenomenon in the body and should not be taken too seriously. If there is any discomfort, please consult your doctor.