Complex sentence: Her head snapped back suddenly at the impact and although she walked out of the arena after the game, she died two days later from an artery in her neck which was damaged by the sudden movement of her head.
Split into simpler sentences: Her head snapped back suddenly at the impact, and although she walked out of the arena after the game, she died two days later. An artery in her neck had been damaged by the sudden movement of her head.