Skeletal System

Gram for gram, compact bone is stronger than steel. Its hierarchical structure of collagen fibers and hydroxyapatite crystals gives it both flexibility and hardness. Unlike steel, bone is living tissue: it is constantly remodelled by osteoblasts (cells that build bone) and osteoclasts (cells that break it down). The entire skeleton is replaced roughly every 10 years. The femur (thigh bone) can withstand compressive forces of up to 1,700 kg.

Known as a cervical rib, this additional rib grows from the base of the neck, near the seventh cervical vertebra. While often harmless, it can sometimes cause nerve or blood vessel compression, leading to medical issues like thoracic outlet syndrome.