A lower transverse plane midway between the upper transverse and the upper border of the pubic symphysis; this is termed the intertubercular plane (or transtubercular), since it practically corresponds to that passing through the iliac tubercles; behind, its plane cuts the body of the fifth lumbar vertebra.
This article incorporates text in the public domain from page 1315 of the 20th edition of Gray's Anatomy (1918)