Your arm muscles cause your forearm bones to move through contraction and relaxation, which pulls on the bones via tendons, producing movement at the joints.
How Arm Muscles Move Forearm Bones
- Muscle Contraction and Tendons: Skeletal muscles are attached to bones by tendons. When a muscle contracts, it shortens and pulls on the tendon, which then pulls on the bone to which it is attached, causing the bone to move
- Antagonistic Muscle Pairs: Muscles work in pairs called antagonistic pairs. For example, to bend the elbow, the biceps brachii contracts (agonist) pulling the forearm bones to flex the elbow, while the triceps brachii relaxes (antagonist). To straighten the arm, the triceps contracts and the biceps relaxes
- Forearm Movements: The forearm bones (radius and ulna) move mainly at the elbow and radio-ulnar joints. Muscles in the upper arm (like biceps and triceps) control flexion and extension of the forearm. Forearm muscles control pronation and supination (rotating the palm down or up) by moving the radius around the ulna
- Forearm Muscle Compartments: The forearm has anterior (flexor) muscles that flex the wrist and fingers and pronate the forearm, and posterior (extensor) muscles that extend the wrist and fingers. These muscles pull on the forearm bones to create movement
- Neuromuscular Control: Movement starts with a nerve signal that triggers muscle contraction at the neuromuscular junction. Acetylcholine release causes muscle fibers to contract, pulling on bones
In summary, your arm muscles contract and pull on the forearm bones via tendons, causing the bones to move at the joints. Different muscles coordinate to produce bending, straightening, and rotation of the forearm
