The radius is one of the two bones in the lower arm, along with the ulna. The radius plays a crucial role in forearm rotation and wrist movement, allowing for supination and pronation of the hand. It also supports the muscles of the forearm and provides attachment points for ligaments and tendons involved in arm and hand movements. The radius's position and structure contribute to the overall strength and stability of the arm, enabling a wide range of activities such as lifting, gripping, and manipulating objects with precision.