Spina iliaca posterior superior

spina iliaca posterior superior –>
posterior superior iliac spine
The posterior extremity of the iliac crest, the uppermost point of attachment of the sacrotuberous and posterior sacroiliac ligaments; a readily apparent dimple occurs in the skin overlying the posterior superior iliac spine which is clinically useful as an indication of the level of the S-2 vertebra, the level of the inferior limit of the subarachnoid space.
Synonym: spina iliaca posterior superior.