Muscle Group of the Week: Anterior Forearm Compartment

Your anterior forearm compartment consists of three muscular layers.  The superficial layer includes the flexor carpi ulnaris, palmaris longus, flexor carpi radialis, and pronator teres.  Below that is the intermediate layer, which consists of one muscle called the flexor digitorum superficialis.  In the deep layer, there lies the flexor digitorum profundus, flexor pollicis longus, and pronator quadratus.

What Does it Do?

Just about any action involving finger or wrist movement activates the anterior forearm compartment muscles.  When you’re using a computer, these muscles are at work when you type and roll the mouse.  If you work in retail, they’re activated when you flick your wrist to scan items.  You also use these muscles in sports that involve direct impact with the hand, such as volleyball or water polo.

From superficial to deep, what exactly do these individual muscles do?

Superficial Flexors:

• Flexor carpi ulnaris
  • Wrist flexion
  • Wrist adduction
• Palmaris longus
  • Wrist flexion
  • Palmar aponeurosis tension
• Flexor carpi radialis
  • Wrist flexion
  • Wrist abduction
• Pronator teres
  • At radioulnar joint: forearm pronation
  • At elbow joint: forearm flexion

Intermediate Flexors:

• Flexor digitorum superficialis
  • Finger flexion

Deep Flexors:

• Flexor digitorum profundus
  • Finger flexion
• Flexor pollicis longus
  • Thumb flexion
• Pronator quadratus
  • Forearm pronation

Making it Strong

You’ve probably heard of pain conditions like carpal tunnel syndrome and tendonitis.  The most common cause of these conditions, and really any pain or weakness in the wrist, is overuse of the forearm muscles.  Prevent tendon thickening and ligament compression through flexor strengthening.

Here are some easy ways to strengthen the anterior forearm muscles:

Wrist Flexion with Resistance Band

The Best Stretches

Now that you’re done with your wrist strengthening equipment, you’ll need to mobilize your joints to keep the flexors flexible!  Here’s what you should do after a good forearm/wrist/hand/finger workout:

Thumb Stretch

Keeping it Happy

When it comes to bodywork, the forearms are often undertreated.  This shouldn’t be the case, considering how many of us use handheld devices and work at desks.

One of the best treatments for tight forearm flexors is the pin-and-stretch technique.  With this modality, your therapist will press down into the origin site of the specific forearm muscle, then glide towards the insertion site while you flex and extend your wrist.  This will allow the therapist to break up the muscular adhesions while you lengthen and shorten the muscle. If you’d like to try pin-and-stretch on yourself when you’re at home, the video below gives a helpful demonstration.

Deep tissue massage, heat therapy, and assisted stretching are also effective when treating the anterior forearm compartment.  Assisted stretching is especially helpful for treating the forearm extensors, which weaken in response to locked-short forearm flexors.  After the flexors have had their knots removed, your therapist can perform proprioceptive neuromuscular facilitation, or PNF, on the posterior forearm compartment.

Now You Know!

Let the fingers and wrists flex!  Pronate the forearm to its full range of motion!  Dominate in volleyball!

When your forearm flexors are strong, something as innocuous as clicking a mouse shouldn’t send you into full blown wrist tendonitis.

Next time, we’ll talk about the anterior forearm’s antagonist muscle group: the forearm extensor muscles.

Resources

Karunaharamoorthy, MD, A. (2023). Deep anterior forearm muscles. [online] Kenhub. Available at: https://www.kenhub.com/en/library/anatomy/the-deep-flexors-of-the-forearm.

Kenhub. (n.d.). Superficial anterior forearm muscles. [online] Available at: https://www.kenhub.com/en/library/anatomy/the-superficial-flexors-of-the-forearm.

Mitchell, B. and Whited, L. (2018). Anatomy, Shoulder and Upper Limb, Forearm Muscles. [online] Nih.gov. Available at: https://www.ncbi.nlm.nih.gov/books/NBK536975/.

Sears, B. (2022). How to Strengthen Your Wrists. [online] Verywell Health. Available at: https://www.verywellhealth.com/wrist-strengthening-exercises-2696622.

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