What do muscles do and what do they pull bone movements through

Muscles pull bone movement through the coordinated contraction of tendons and muscle belly. The contraction of skeletal muscles is mainly triggered by nerve signals, which transmit force to the bones through tendons, thereby generating joint activity.

1. Tendon Function

Tendons are dense connective tissue that connects muscles and bones and have high tensile strength. When the muscle contracts, the tendon transmits tension to the bone attachment point, similar to pulling a lever with a rope. For example, the Achilles tendon transmits the strength of the triceps muscle to the heel bone, achieving a tiptoe movement. The arrangement direction of collagen fibers in tendons is consistent with the direction of force, which can effectively reduce energy loss.

2. Muscle Abdomen Contraction

The muscle abdomen is composed of a large number of muscle fiber bundles, which contract upon receiving signals from motor neurons. The myosin inside the muscle fibers slides with actin filaments to generate mechanical force, which shortens the muscle segments to achieve overall muscle contraction. Different types of muscle fibers affect contraction speed and endurance. Fast muscle fibers have strong explosive power, while slow muscle fibers are suitable for continuous exercise.

III. Neuroregulation

Spinal cord anterior horn motor neurons release acetylcholine through neuromuscular junctions, triggering depolarization of muscle cell membranes. The recruitment principle of sports units determines the number of muscle fibers involved in contraction. Fine movements require activation of small sports units, while jumping and other movements require the mobilization of a large number of sports units for synchronous discharge.

4. Skeletal Leverage

Bones serve as a lever system that amplifies or changes the direction of force through joint pivot points. The distance between the muscle attachment point and the joint determines the magnitude of the torque. For example, if the stop point of the biceps brachii muscle is far away from the elbow joint, it can efficiently complete the elbow flexion movement. Different joint types allow for a specific range of motion in a particular direction.

Fifth, Collaborative Mechanism

During active muscle contraction, the antagonistic muscles need to be appropriately relaxed to avoid movement conflicts, such as inhibiting the contraction of the triceps during elbow flexion. Fixed muscles maintain joint stability, such as the core muscle group maintaining a neutral position of the spine during limb movements. This neuromuscular coordination is achieved through the regulation of the cerebellum and basal ganglia.

To maintain the health of the musculoskeletal system, resistance training should be combined to enhance muscle strength. Compound movements such as squats and push ups can stimulate the coordination of multiple muscle groups. Simultaneously supplementing high-quality protein and vitamin D promotes muscle fiber repair, avoiding sudden increase in exercise intensity that may cause tendon damage. Middle aged and elderly people are advised to engage in water exercise to reduce joint load, while children and adolescents should pay attention to learning movement patterns to establish correct neuromuscular control.