To allow motion, different bones are connected by joints. Cartilage prevents the bone ends from rubbing directly on to each other. Muscles contract (bunch up) to move the bone attached at the joint.
为了能够运动,不同的骨骼通过关节彼此连接。软骨可以防止骨骼末端直接相互摩擦。肌肉收缩(聚成一团)以移动附着在关节处的骨骼。