In vertebrate anatomy, hip (or "coxa" in medical terminology) refers to either an anatomical region or a joint. The hip region is located lateral and anterior to the gluteal region (i.e., the buttock), inferior to the iliac crest, and overlying the greater trochanter of the femur, or "thigh bone". In adults, three of the bones of the pelvis have fused into the hip bone or acetabulum which forms part of the hip region. Pain of the hip may be the result of numerous causes including nervous, osteoarthritic, infectious, trauma-related, and genetic ones.