pelvic girdle

The pelvis girdle (also called pelvis) is the large bone structure between the hips. The pelvis consists of the following bones that are connected by joints:

• sacrum
• tailbone
• left hip bone
• right hip bone

These joints don't give a lot of movement freedom. Only with women if they get pregnant, these joints get more flexible to facilitate the birth of the child. One of these joints is the pubic symphysis
The left and right hip bone are a fusion of the following bones:

• Ilium
• Pubic bone
• Ischium bone

This fusion of the hip bone usually happens during puberty.