This chapter discusses the anatomy and disorders of the musculoskeletal system. Bone is divided into 2 components: cortical or compact bone and trabecular or cancellous bone. Bone consists of large quantities of extracellular matrix which is loaded with calcium hydroxyapatite and relatively small number of bone cells which are of 3 main types besides the ground substance, the osteoid matrix. Osteoblasts are uninucleate cells found abundantly along the new bone-forming surfaces. The cartilage lacks blood vessels, lymphatics and nerves. It may have focal areas of calcification. Cartilage consists of cartilage matrix and chondrocytes. An infection of the bone is termed osteomyelitis. Suppurative osteomyelitis is usually caused by bacterial infection and rarely by fungi. Pyogenic osteomyelitis by haematogenous route occurs most commonly in the long bones of infants and young children. Avascular necrosis of the bones or osteonecrosis results from ischaemia. Osteopetrosis, also called marble bone disease, is an autosomal dominant or recessive disorder of increased skeletal mass or osteosclerosis caused by a hereditary defect in osteoclast function. Fluorosis of bones occurs due to high sodium fluoride content in soil and water consumed by people in some geographic areas and is termed endemic fluorosis.