We’ve now seen all the extrinsic muscles of the hand. Before we move on to look at the intrinsics, let’s back up, and see how the extrinsics fit in with the elbow muscles, the rotator muscles, and the wrist muscles that we saw in the last section. If you’d like to use this next overview as a review section, turn off the sound.
Here are all the muscles intact. Here’s biceps, brachialis, and brachioradialis. We’ll remove brachioradialis. Here, arising from the medial epicondyle and sharing the common extensor tendon, are pronator teres, partly hidden, and the three wrist flexors, flexor carpi radialis, palmaris longus, and flexor carpi ulnaris.
We’ll remove the three wrist flexors, but leave pronator teres still in place. Here’s flexor digitorum superficialis. Its long oblique origin runs right next to pronator teres.
We’ll remove pronator teres now, and flexor digitorum superficialis. Here are the three deepest muscles, flexor digitorum profundus, flexor pollicis longus, and beneath them all, pronator quadratus.
Now let’s look at all the muscles of the extensor aspect of the forearm. We’ve already removed brachioradialis, it went from here to here. Here are extensor carpi radialis longus, and brevis, and extensor carpi ulnaris. Here between the wrist extensors, sharing the common extensor tendon, is extensor digitorum.
We’ll remove the wrist extensors so that we can see extensor digitorum by itself. Here's extensor digitorum. Supinator lies deep to it here, and distally the three long thumb muscles emerge from beneath it.
Removing extensor digitorum, we see supinator, abductor pollicis longus, extensor pollicis brevis and longus, and extensor indicis.