Bones are the hard parts that form the skeleton. Bones support the body and protect its internal organs. Bones act as anchors for muscles as levers for the movement of limbs and are the main reserves of calcium and phosphate in the body Muscles support the bones to provide good posture. Muscles produce movement in the body. Muscles are made up of bundles of fibres that are composed of smaller fibres. The fibres in muscles can tear, but will usually heal.