Absolutely Everything You Need to Know About the Flexor Digitorum Superficialis

Inside: The flexor digitorum superficialis bends your fingers and wrist. If you type, text, or hold a coffee cup; learn how to keep this muscle healthy.

The dexterity of our hands has always been important. Whether our ancestors were building a fire, gathering berries, or making a sweet pair of leggings; they were using their hands. Even though our daily activities have changed, the health of our hands is still just as important.

One of the hand muscles that help us keep functioning is the flexor digitorum superficialis. You may not have ever heard of this muscle, but it’s the one responsible for bending your fingers and flexing your wrist. As I write this and as you hold your mobile device to read this, we are using this important muscle.

Here’s more about the flexor digitorum superficialis, where it is, what it does, and how to keep it healthy.


flexor digitorum superficialis

Thanks to the University of Washington Radiology for the image.

The flexor digitorum superficialis has two points of origin. The first is on the humeroulnar head, which is a fancy name for the hinge joint of your elbow where your humerus and ulna meet. At this location, the muscle originates on the medial epicondyle of the humerus via the common flexor tendon, ulnar collateral ligament, and the coronoid process of the ulna.

So, if your palm is facing forward, this point of origin is just above your elbow, on the part of your upper arm closest to your body.

The second point of origin is on the radius. Flexor digitorum superficialis originates on the oblique line of the radius from the radial tuberosity to the insertion of the pronator teres. This means that this point of origin runs down part of the edge of the radius.

When your palm is facing forward, the radius is your lower arm bone that is further from the midline of your body.

The flexor digitorum superficialis inserts via 4 tendons (one for each finger). They divide for the passage of the tendons of the flexor digitorum profundus, and then insert on either side of the shaft of the middle phalanx for each finger. This means that this muscle inserts on the sides and just above the joint of your middle knuckle on each finger.


The flexor digitorum superficialis bends your fingers at the middle knuckle and bottom knuckle (where your fingers join your hand). It even flexes the hand at the wrist. This means that it helps the palm of your hand come closer toward your forearm.

Common Dysfunction

If it is painful, difficult, or impossible to bend your fingers or wrist; you might have a dysfunctional flexor digitorum superficialis. Since this muscle’s whole function is bending the fingers and flexing the hand at the wrist, if any of those activities are limited or impaired, it’s a safe bet that this muscle isn’t quite working correctly.

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 flexor digitorum superficialis healthy, I have some suggestions. For optimal muscle health, you want to both strengthen and stretch this muscle. To strengthen this muscle, you should practice flexing your fingers and wrist. You want to make sure to curl your fingers at your middle knuckle and deeply bend the bottom knuckle to bring your fingers closer to the palm of your hand. Remember to also flex your wrist (think “Walk Like an Egyptian” hands).

To stretch a muscle, you should do the opposite movement from its function. So, in this case, you want to extend your fingers and your wrist. Use your other hand to carefully provide a stretch to your middle and bottom knuckles. Or, if you’re a knuckle cracker, here’s your excuse to do your thing.

Make sure to stretch your wrist as well. An easy way to do this is by gently pressing your palms onto a table.

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 flexor digitorum superficialis? Let us know in the comments below.

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About Sarah Stockett

Hi, I'm Sarah! I'm a certified Pilates and yoga instructor with a passion for pain relief. I believe you can use simple exercises to relieve your aches + pains. AND, I believe I can teach you how.