Anatomy of the muscles that move the wrist

As for the muscles that move the wrist joint, some of them are flexors, some are extensions, some turn the hand down with the palm, others turn it up with the palm.

The extensor muscles include a muscle that adjoins another muscle, forming, as it were, one muscle, because this muscle grows from the middle of the lower “flint” and its tendon is adjacent to the thumb, which, with the help of this muscle, moves away from the index finger. And the other muscle

grows from the upper “flint” and its tendon adjoins the first bone of the wrist, that is, the bone located under the thumb. When both of these muscles move simultaneously, they extend the wrist, turning it slightly downward with the palm of the hand. If only the second muscle moves, it tilts the wrist, and when only the first muscle moves, it moves the thumb away from the index finger.

There is another muscle, draped over the upper “flint” from the outside, which starts from the lower parts of the head of the humerus. It sends the biceps tendon adjacent to the middle of the metacarpus in front of the middle and index fingers. The head of its tendon rests on the upper “flint” near the wrist and extends the wrist, tilting it down with the palm.

As for the muscles that flex the wrist, there are a couple of them and they are located on the outer side of the forearm. The lower one starts from the inner head of the humerus and reaches the metacarpus in front of the little finger, and the upper one starts higher and reaches the same place.

Another muscle along with them starts from the lower parts of the humerus, in the middle between the location of the mentioned muscles. It has two ends that intersect crosswise, then join the place located between the index and middle fingers. When these muscles move together, they tighten the hand.

The same flexor and extensor muscles perform pronation and supination if muscles that lie obliquely from each other move. When the muscle adjacent to the metacarpus in front of the little finger moves alone, it slightly rotates the hand; if it is helped by the muscle of the thumb, which we will talk about later, then a complete turn of the hand occurs with the palm up.

If the muscle adjacent to the wrist in front of the thumb moves alone, it turns the hand slightly downwards with the palm, moving together with the muscle of the little finger, which we will talk about later; this muscle rotates the hand completely.