Inside: Your extensor pollicis longus and extensor pollicis brevis muscles help move your thumbs. Learn about these important muscles and how to keep them healthy.

Of all the digits on the hand, you might say that the thumb is the most important. It’s what allows us to grip jars and pour coffee (among other important tasks). Your thumb’s health and ability to move correctly is directly impacted by the health of your extensor pollicis longus and extensor pollicis brevis. Here’s more about these important muscles and how to keep them healthy.

Location

The origin of the extensor pollicis longus is on the posterior surface in the middle third of the ulna. It also originates on the interosseous membrane.

So, if you’ve got your palm on a table, you can feel the point of origin for the extensor pollicis longus along the outside of your forearm about one-third of the way up heading away from your wrist.

According to Flash Muscle Flash Anatomy Cards, the insertion for the extensor pollicis longus is on the “posterior surface of the base of the distal phalanx of the thumb.” This means that this muscle runs past your wrist, along the back of your hand, and inserts on the very top joint of your thumb.

The origin of the extensor pollicis brevis is on the posterior surface of the distal end of the radius. The distal end is the part of the radius that is further away from the midline of the body. This means this point of origin is near the wrist.

The insertion point of the extensor pollicis brevis is at about the same spot of insertion for the extensor pollicis longus. This means that it’s on the back of the very top joint of your thumb.

Function

The main function of the extensor pollicis longus is to extend the thumb at several joints. Specifically, it extends both the distal and proximal phalanges of the thumb and the metacarpal. The phalanges are the joints in the thumb, and the metacarpal is the bone in your hand right beneath your thumb. To extend your thumb, you would lift it off of a flat surface.

Additionally, this muscle adducts the first metacarpal. This means that it helps the bone right beneath your thumb slide closer toward the other bones in your hand.

The extensor pollicis brevis has a similar, although reduced, function. It mainly extends the thumb at the joint where it joins the palm.

In direct contrast to the extensor pollicis longus, the additional function of the extensor pollicis brevis is to abduct the first metacarpal. This means that this muscle helps the bone in the palm of your hand in line with your thumb move away from the other bones in your hand.

Common Dysfunction

If you have difficulty or pain when you extend your thumb, you could possibly have dysfunctional extensor pollicis longus or extensor pollicis brevis muscles. Similarly, if you notice that you have pain in the palm of your hand beneath your thumb, you might also have issues.

Yet another indicator of dysfunction is pain or inability when you move your thumb toward or away from your other fingers. Remember, your extensor pollicis longus helps move the bone in the palm of your hand toward the other bones; the extensor pollicis brevis helps move the bone away from the other bones.

Restoring or Maintaining Health

Any time you think that you have injured or torn a muscle, you need to contact your doctor immediately. Your doctor can order all of the appropriate imaging, medicine, and therapy necessary for you to heal as quickly and thoroughly as possible.

However, if you want to keep the extensor pollicis longus and extensor pollicis brevis healthy, I have some suggestions. For optimal muscle health, you want to both strengthen and stretch these muscles. To strengthen them, you should practice extending your thumb.

You should also move your thumb both toward and away from your other fingers. This will be a strengthening exercise for one muscle and a stretch for the other. Then, when you move your thumb the other way, the roles will switch.

Both muscles will receive a stretch when you allow your thumb to curl in toward your palm. Make sure to bend at all the joints so that you can experience the maximal stretch. These strengthening and stretching exercises aren’t glamorous, but they’ll help keep your extensor pollicis longus and extensor pollicis brevis muscles healthy.

More Information

For those who are more interested in technical terminology and smaller muscles, I recommend Flash Anatomy Muscles Flash Cards. Any time a client comes to me with pain, I use these flash cards.

Do you have any other suggestions for strengthening or stretching the extensor pollicis longus or the extensor pollicis brevis? Let us know in the comments below.

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