A look at the muscles at work during arm flexion and extension. Flexion activates the biceps brachii, brachialis, brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis, while extension engages the triceps brachii and anconeus—each contributing to controlled movement. A huge thank you to everyone supporting the project by purchasing our apps, donating, or subscribing here on Instagram. Your support makes this possible! #anatomystandard #workinprogress #3danatomy #fun