Pelvic brim

The pelvis is divided by an oblique plane passing through the prominence of the sacrum, the arcuate and pectineal lines, and the upper margin of the symphysis pubis, into the greater pelvis and the lesser pelvis. The circumference of this plane is termed the pelvic brim. The "linea terminalis" consists of the pectineal line, the pubic crest and the arcuate line