Back dimples, often referred to as the Dimples of Venus (or Apollo in men), are small, symmetrical indentations that appear on the lower back, just above the buttocks. Their presence is purely a matter of individual anatomy, stemming from a specific structural configuration in the lower back. This trait is not universally present. While often considered an aesthetically pleasing feature, these indentations are entirely harmless.
The Anatomy of Back Dimples
The indentations known as back dimples have a precise anatomical cause, which is purely structural and not related to muscle or fat. They are located directly over the sacroiliac joints, which are the points where the sacrum bone connects to the ilium, a part of the pelvis. This location places them slightly superior to the gluteal cleft on either side of the spine.
The dimples themselves are formed by a short, fixed ligament that stretches between the skin and the posterior superior iliac spine (PSIS), a bony prominence on the pelvis. This ligament anchors the skin to the underlying bone structure, creating the slight depression visible on the surface. Because the indentation is caused by this connective tissue anchoring, it is not possible to create or enhance back dimples through exercise or muscle development.
These indentations are a fixed connection point present from birth. They may become less noticeable as a person ages or gains weight, but the underlying anatomical structure remains unchanged. The formal anatomical term for these features is fossae lumbales laterales, or lateral lumbar indentations.
Why Only Some People Have Back Dimples
Not everyone possesses back dimples. Their presence is largely determined by genetics, which controls the length and placement of the specific ligament structure. While the exact genes responsible have not been definitively identified, they are considered an inherited trait, often following a dominant inheritance pattern.
This hereditary factor explains why the trait is passed down through generations and appears in some families and not others. Even if the genetic potential for the dimples exists, their visibility is heavily influenced by body composition. Individuals with a lower body fat percentage often find their back dimples are more pronounced and easier to see.
The dimples are a variation in connective tissue structure. They may appear more frequently or more prominently in females, which is why they are often associated with the Roman goddess of beauty, Venus. Body changes can affect how noticeable they are, but they cannot be newly acquired.
When Back Dimples Are Not Just Cosmetic
While the common back dimples (Dimples of Venus) are harmless cosmetic features, other indentations on the lower back can sometimes be medically significant. It is important to distinguish the two Venus dimples from a sacral dimple, which is typically a single indentation located much lower, right above the crease of the buttocks. Sacral dimples are congenital and usually benign, occurring in a small percentage of newborns.
However, a sacral dimple can occasionally be a subtle external marker for an underlying spinal issue, such as spina bifida occulta. This mild form of spina bifida occurs when the vertebrae do not completely close around the spinal cord during development, though it often causes no symptoms. Atypical features accompanying a sacral dimple can raise concern, including a tuft of hair, a skin tag, or unusual skin discoloration around the indentation.
In these instances, a healthcare provider may recommend further testing, such as an ultrasound of the sacrum, to ensure the spinal cord is properly formed and not tethered. If a dimple appears deep, unusually placed, or is accompanied by these other skin changes, professional consultation is necessary to rule out any underlying anatomical variations.