Sankaku Channel/dimples of venus

The dimples of Venus (also known as back dimples, butt dimples or Venusian dimples) are sagittally symmetrical indentations sometimes visible on the human lower back, just superior to the gluteal cleft. They are directly superficial to the two sacroiliac joints, the sites where the sacrum attaches to the ilium of the pelvis.

The term "dimples of Venus", while informal, is a historically accepted name within the medical profession for the superficial topography of the sacroiliac joints. The Latin name is fossae lumbales laterales ("lateral lumbar indentations"). These indentations are created by a short ligament stretching between the posterior superior iliac spine and the skin. They are thought to be genetic.

There are other deep-to-superficial skin ligaments, such as "Cooper's ligaments", which are present in the breast and are found between the pectoralis major fascia and the skin.

There is another use for the term "Dimples of Venus" in surgical anatomy. These are two symmetrical indentations on the posterior aspect of the sacrum which also contain a venous channel. They are used as a landmark for finding the superior articular facets of the sacrum as a guide to place sacral pedicle screws in spine surgery.

They are sometimes believed to be a mark of beauty, alluding to the origin of their name (Venus was the Roman goddess of beauty).
--WIKIPEDIA--

Dimples of Venus are back dimples. They are two indents on each side of the spine right above the butt. They are genetic, so you can't gain them by doing certain exercises but you can define them by doing just that. Dimples of Venus usually hit during puberty, generally on women. Most people find them very attractive or cute.
Dimples of Venus is believed to be a blessing from the god of Venus.
--URBAN DICTIONARY--

See: http://upload.wikimedia.org/wikipedia/commons/b/bb/Dimples_of_Venus_while_seated_%28with_arrows%29.jpg