The forearm muscles (wrist muscles) are important for grip strength, and strong forearms can help to improve overall upper body strength. This page gives a brief overview of the anatomy of the forearm.
Strong wrist muscles can improve performance in sports and daily activities, but the forearms are neglected in most fitness programs.
The forearm is divided anatomically into the anterior (front) compartment and the posterior (back) compartment.
Some muscles in the forearm go down to the wrist bones and move and stabilize the wrist. Other muscles in the forearm go all the way down to the fingers to move and stabilize the fingers.
Below, I use the technical names mixed in with more understandable terms. But many muscles are named after the motions they do.
The muscles on the anterior forearm play a role in bending the wrist and fingers, and forming a fist.
There are 8 muscles in the front of the forearm, and the front of the forearm is sub-divided into 3 layers the superficial, intermediate, and deep layers.
The superficial layer has 4 muscles, the pronator teres, flexor carpi radialis, palmaris longus, and the flexor carpi ulnaris.
The pronator teres turns the palms down and assist at bending the elbow, and the other three muscles in the superficial layer bend the wrist (flex the wrist).
What is unique about the superficial layer is that they all start on a common tendon on the inside part of the humerus (the medial epicondyle)-- the big bone that sticks out on the inside part of the elbow joint.
Overuse/ tendonitis of these muscles is often referred to as "Golfers Elbow" or medial epicondylitis.
The intermediate layer contains only one muscle, the flexor digitorum superficialis, but this muscle is large and goes to all 4 of the fingers.
The name says what it does. It is the superficial muscle that flexes (bends) the fingers. It obviously helps with grip strength.
The deep layer of the anterior forearm contains 3 muscles: the flexor digitorum profundus, flexor pollicis longus, and the pronator quadratus.
The flexor digitorm profundus works with the superficialis to bend the fingers.
Pollicis refers to the thumb, so this muscle helps to bend the thumb, and the pronator quadratus helps to turn the palms down (pronation of the forearm).
The muscles in the posterior forearm work to extend or straighten the wrist and fingers.
There are 12 muscles on the back of the forearm, and they are sub-divided in 2 layers: superficial and deep.
The superficial layer contains 7 muscles: the brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, and the anconeus.
The brachioradialis is the "hand shake muscle". It actually bends your elbow when your arm is in the position to shake someone's hand. And it works hard during exercises like hammer curls.
The other muscles in the superficial layer play a role in straightening/ extending the wrist and stabilizing the wrist.
Similarly to the anterior compartment, many of the muscles in the posterior compartment attach to a common tendon on the outside of the elbow (the lateral epicondyle).
Overuse and tendinitis at the lateral epicondyle is referred to as "Tennis Elbow" or lateral epicondylitis.
The deep layer contains 5 muscles: the supinator, abductor pollicis longus, extensor policis brevis, extensor pollicis longus, and the extensor indicis.
The supinator turns the palms face up.
Pollic refers to the thumb. The Abductor pulls the thumb out to the side and the extensors pull the thumb backwards.
Indicis refers to the index finger, and this muscle pulls the index finger backwards.
Don't be so worried about remembering all the names of all the forearm muscles.
Just think the muscles on the front of the forearm bend the wrist and fingers, and the muscles on the back of the forearm straighten the wrist and fingers.
When you are holding things, both groups of muscles work together to stabilize the fingers and wrists.
If you really want to increase your upper body strength try adding in some forearm exercises into your workout. And if you play a sport that involves your arms, building up your forearms may improve your performance.
Hope that helps to makes it easier to understand the forearm and wrist muscles.
Yours in Health,
Dr. Charles PT/PT
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