The muscular-skeletal system is derived from the mesoderm, and in humans is called an endoskeleton. Insects such as beetles or shellfish such as lobsters have hard exoskeletons. It provides structural rigidity and support to the human body, and also acts in calcium and mineral storage and physical protection against injury
The skeleton contains both cartilage and bone
Cartilage is secreted by chondrocytes, which consist of a firm but elastic matrix called chondrin and is what composes the majority of the fetal skeleton. It begins to calcify into bone during the pre and postnatal stages of development. In an adult, cartilage forms the ear, nose, larynx and the joints. A lack of cartilage in older adults is what causes arthritis. Cartilage is avascular which means it does not contain blood or lymphatic vessels.
See Axial Skeleton
Axial Skeleton consists of the skull, the vertebrae column, and the rib cage, which act as a support structure for the core of the body.
Appendicular Skeleton consists of all of the limbs, the arms and the legs, and the pelvic and pectoral girdles. These both provide stability and reinforcement of for the body.