These are long and thin, arranged in small bundles, each one controlled by a nerve. Bundles of these contract when stimulated by a nerve. When the impulses stop, it relaxes. In this manner we control body movements.

These are long and thin, arranged in small bundles, each one controlled by a nerve. Bundles of these contract when stimulated by a nerve. When the impulses stop, it relaxes. In this manner we control body movements.

• A. Cartilage
• B. Bones
• C. Muscle fibers
• D. Tendons

Answer: (C)

Muscle fibers are long, thin cells arranged in small bundles, and each fiber is controlled by a motor nerve. When a nerve impulse reaches a fiber, the fiber contracts, and the bundles shorten to generate movement. When the impulse stops, the fibers relax, allowing the body part to return to its resting state. This contraction-and-relaxation cycle enables our voluntary movements.

Cartilage and bones do not contract—cartilage provides cushioning and support, and bones provide rigid structure. Tendons connect muscle to bone and transmit the force of contraction, but they do not contract themselves.