The iliac crests are used as a landmark for locating the position of L4 to L5 for a lumbar puncture; they are identified and traced medially toward the vertebral column. The inferior angles of the scapulae lie at vertebral level T7; the lowest ribs lead one to T12; a line between the posterior superior iliac spines crosses vertebral level S2; the posterior inferior iliac spines lie below S2.