The hip bone (innominate bone, pelvic bone or coxal bone) is a large, Flat bone, constricted in the center and expanded above and below. In some vertebrates (including humans before puberty) it is composed of three bones; ilium, ischium, and pubis.
The two hip bones joins at the pubic symphysis and together with the sacrum and coccyx, the hip bone comprises the skeletal component of the pelvis, the pelvic girdle, which surrounds the pelvic cavity. The hip bone forms the primary connection between the bones of the lower limb and the axial skeleton. They are connected to the sacrum, which is part of the axial skeleton, at the sacroiliac joint. Each hip bone is connected to the corresponding femur, which is part of the lower limb, through a large ball and socket joint, the hip joint.
The human body is the entire structure of a human organism and comprises a head, neck, torso, two arms and two legs. By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life. These cells are organised biologically to eventually form the whole body.