<prompt> Highest point of iliac crest is seen at;L3L4S1S2  <response>: Highest point of iliac crest lies at the level of the 4th lumbar veebral body L4. Clinical significance: Site of bone marrow harvests to collect the stem cells used in bone marrow transplantation. Most ideal donor site forbone grafting when a large quantity of bone is needed. To estimate site for lumbar puncture as LP is done at the level bw L3-L4 or bw L4-L5 and highest point of iliac crest coincides with it. 