The motion system of human body consists of bones and muscles, and bones are connected by many bones. As shown in the figure, the thin and milky white parts at both ends of skeletal muscle are tendons (genus? In connective tissue), 6 are attached to two adjacent bones respectively. The thick part in the middle is the muscle abdomen, which is mainly composed of muscle tissue. There is a connective tissue membrane outside, and there are many blood vessels and nerves inside. Skeletal muscle has the property of stimulating contraction. During exercise, the contraction and relaxation of muscles will pull six bones around six joints. During exercise, the nervous system plays a regulatory role, bones play a lever role, and joints play a fulcrum role.

So choose: C.