pelvic arch -
the structure of the vertebrate skeleton supporting the lower limbs in humans and the hind limbs or corresponding parts in other vertebrates
os pubis,
pubic bone,
pubis one of the three sections of the hipbone; together these two bones form the front of the pelvis
sacrum wedge-shaped bone consisting of five fused vertebrae forming the posterior part of the pelvis; its base connects with the lowest lumbar vertebra and its tip with the coccyx