The skeletal system helps provide support, protection, movement, mineral (and lipid) storage, and areas (marrow_cavities) where blood cell formation occurs. Each bone in the skeletal system has a unique shape, size, and surface markings.

There are two divisions of the human skeleton: axial and appendicular. The axial skeleton is divided into three sections: the skull, vertebral_column, and the thorax.

The human skull is divided into two sections: the cranium and the face. All but one of the bones of the skull are joined by interlocking joints, which are called sutures. The mandible (lower jawbone) is the exception: it is attached to the rest of the skull by a freely movable joint.