posterior superior iliac spine
PSIS

These indentations are created by a short ligament stretching between the posterior superior iliac spine and the skin.

It is one of two such spines on the posterior surface, the other being the posterior superior iliac spine.

It is thinner at the center than at the extremities, and ends in the anterior and posterior superior iliac spines.

The pain is often a mild to moderate ache around the dimple or posterior superior iliac spine (PSIS) region.

The posterior superior iliac spine serves for the attachment of the oblique portion of the posterior sacroiliac ligaments and the multifidus.

The multifidus muscle in the sacral region attaches to the medial surface of posterior superior iliac spine, the posterior sacroiliac ligaments and several places to the sacrum.

The posterior border of the ala, shorter than the anterior, also presents two projections separated by a notch, the posterior superior iliac spine and the posterior inferior iliac spine.

The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS).

The apparent masses of the subjects were determined together with transmissibilities measured from the seat to various locations on the body surface: the upper and lower abdominal wall, at L3, over the posterior superior iliac spine and the iliac crest.

The sacrotuberous ligament is attached by its broad base to the posterior superior iliac spine, the posterior sacroiliac ligaments (with which it is partly blended), to the lower transverse sacral tubercles and the lateral margins of the lower sacrum and upper coccyx.