Forearm Pain – Essential anatomy of forearm muscles.

What Kind of Forearm Pain?

Forearm pain has lots of different names and causes. So, do you have Tennis Elbow?  Golf Elbow?  Biceps Tendinitis? De Quervain’s Syndrome? or Arthritis? With such a complicated arrangement of forearm muscle it can be difficult to decide. Read on and I’ll help you to work it out for yourself…


The forearm is the part of the arm found between the elbow joint and the wrist joint – Forearm pain can come from many of the structures here. The forearm anatomy is made up of two long bones, the Radius and the Ulna, the upper ends of which form part of the elbow joint and the lower ends form part of the wrist joint. Attached to these two bones forearm muscles produce movements at the elbow wrist and hand. By having long thin tendons passing to the hand forearm muscles act at a distance from their attachment. This means that the wrist and hand can be slim and agile and perform very complicated and demanding tasks while the bulky part of the operation, the muscle bellies, are situated further up the forearm for efficiency. The forearm muscles are responsible for a lot of forearm pain.

The muscles of the forearm can initially be split into two groups – the forearm flexors and the forearm extensors. These terms relate to the movements produced at the wrist.



As you can see from the pictures – with the palm of the hand facing down- EXTENSION of the wrist is the upwards movement of the back of the hand. This movement is localised to the wrist using the muscles of the back of the forearm with no movement elsewhere in the arm.

left extensor forearm pain

Back of left forearm


To extend the wrist forearm extensor group muscles are used.

The main extensor muscles of the wrist and forearm are:-

1 Extensor Carpi Radialis Longus – extends and radially deviates wrist

2 Extensor Digitorum – extends the fingers

3 Extensor Carpi Radialis Brevis – extends and radially deviates wrist

4 Extensor Carpi Ulnaris – extends and ulnarly deviates wrist

5 Abductor Pollicis Longus – abducts the thumb from the palm

6 Abductor Pollicis Brevis – abducts the thumb from the palm

7 Extensor Pollicis Longus – extends the thumb joint

8 Extensor Digiti Minimi – extends the little finger

9 Extensor Indicis – extends the index finger

Each extensor forearm tendon passes across the wrist and runs under a band of fibrous tissue called the extensor retinaculum which hold the tendons in place and stop them ‘bowstringing’ across the back of the joint.

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WristFlexFLEXION of the wrist is the downward movement of the back of the hand (if the palm of the hand is facing downwards)

left flexor forearm pain

Front of left forearm


Flexion is performed by the forearm flexor muscles – this is also a common source of forearm pain. There are two sets of forearm flexors – the superficial ones and the deep ones.

This diagram shows the superficial ones just under the skin. These muscles comprise of :-

1 Flexor Carpi Radialis – flexes and radially deviates the wrist

2 Flexor Carpi Ulnaris – flexes and ulnarly deviates the wrist

3 Palmaris Longus – runs superficial to the flexor retinaculum (7) and attaches to a web of fibrous tissue in the palm of the hand. This muscle is used in animals to ‘bare’ the claws but its function in the human forearm is uncertain – in fact it is absent in about 14% of the population.

4 Flexor Digitorum Superficialis – flexes the fingers

To produce flexion of the ends of the fingers in the hand forearm muscles of the Deep Forearm Flexors are used:-

5 Flexor Pollicis Longus – flexes the thumb

6 Flexor Digitorum Profundus – flexes the fingers

There is a band of fibrous tissue which runs across the wrist and holds the forearm tendons in place and stops ‘bowstringing’. This is called the Flexor Retinaculum (7) and some of the tendons run in their own tunnel under the retinaculum.


There are two bones in the forearm – Radius and Ulna.

The Radius forms a small part of the Elbow Joint and the major part of the Wrist Joint and if you stand in what is known as the ‘anatomical position’ (that is with your arms by your side with your palms facing forwards) then the Radius is the forearm bone that is furthest away from your body on the thumb side.

The Ulna forms the ‘hinge’ part of the Elbow Joint and if you stand in the ‘anatomical position then your Ulna is the bone in the forearm that is nearest your body.

These two bones are joined together at both ends of their shafts. The upper joint is known as the Superior Radio-Ulnar Joint and the lower joint as the Inferior Radio-Ulnar Joint. These joints allow the Radius to move over the fixed Ulna in the movements of supination and pronation which will be described later.

Do you have problems with either of these joints – find out here for FREE

Radial Deviation left wrist


is movement of the hand towards the Radius side of the body.
The forearm tendons of the following muscles are involved in producing the movement:-
1 Flexor Carpi Radialis

2 Extensor Carpi Radialis Longus

3 Extensor Carpi Radialis Brevis

Right Wrist forearm pain

Cross-Section of Right Wrist

Assisted by:-

4 Extensor Indicis

5 Extensor Pollicis Longus

6 Abductor Pollicis Longus

7 Extensor Pollicis Brevis.



is funnily enough the movement of the hand towards the Ulna bone forearm muscles involved are the :-

A Flexor Carpi Ulnaris – This tendon attaches to a small bone in the wrist (the Hammate Bone) just before the cross section is taken which is why you do not see a tendon in the diagram above. The arrow A points to where the ligaments from the Hammate pass into the hand bones transferring the forces of contraction.

B Extensor Carpi Ulnaris & C Extensor Digiti Minimi

left wrist forearm pain

Back of left wrist


This is a band of dense fibrous tissue which as you can see from the diagram holds the extensor tendons in place. deep to the retinaculum there are in fact 6 tunnels each of which are lined with a self-lubricated sheath.

These sheaths control the position of the  individual forearm tendons and the lubricated tunnel helps to eliminate friction as the tendons move back and forth under the retinaculum.

If these tunnels become inflammed and swollen then you get the pain of tenosynovitis and quite often you can hear and feel the tendons ‘creaking’ in the tunnel as they move!


De QUERVAIN’S Syndrome is synovitis of the tendons (or their sheaths) of Abductor Pollicis Longus and Extensor Pollicis Brevis and is associated with new mothers picking up their new babies.

In this technology age it can be known as Blackberry Thumb or Text Message Thumb.

For a FREE Forearm Pain Assessment click the link and find out if you have De Quervain’s Syndrome


As mentioned earlier these movements are about the Radius moving around the fixed Ulna.

Click on the video below for a demonstration of these movements


Pronators of left forearm

Pronators of left forearm


of the forearm is produced by two muscles:-

1 Pronator Quadratus – which is found down near the wrist area of the forearm and sits very deep to all the other muscles and tendons which pass over it. this is the main producer of pronation strength.

2 Pronator Teres – part of the Golf Elbow group of muscles attached to the medial epicondyle.


is produced by two main muscles:-

1 Biceps – which attaches to the shoulder blade (scapula), the humerus and through a strong tendon to the Radius.

2 Supinator – which is part of the Tennis Elbow group of muscles attached to the lateral epicondyle and also has an attachment to the back of the ulna.


If you have a sore forearm it is essential to know what structures are likely to be causing the forearm pain. To complicate things even further it is possible to have pain in your arm without having a forearm tendon or forearm muscle causing the pain even if they are painful to the touch!!

A trapped nerve in the neck or pressure on a nerve as it squeezes through some tight spaces in the arm or passes round some sharp corners can cause pain in the muscles and it takes some specialised tests to tell the difference.

Forearm Pain Assessment Tool

FREE Forearm Pain Assessment click the link

These tests available for you and they are FREE.
So click Forearm Pain Assessment to take the first step towards a pain-free forearm.

Once you have completed the FREE detailed tests you will be given your Specific Rehabilitation Program


You now have a fairly detailed understanding of the forearms and how the hand and forearm are functionally linked to each other. Likewise you now know how some of the key muscles at the arm forearm junction (elbow joints) produce pronation and supination of the forearm. You also can visualise how a forearm tendon passes under the extensor or flexor retinaculum to enter the hand and how this area can be a source of lower forearm pain.

For more specific information on Tennis Elbow or Golf Elbow click on the links below.

Tennis Elbow Lateral Epicondylitis Elbow Injuries – Top 10 Questions Epicondylitis Elbow – Medial Epicondylitis / Golfers Elbow

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Ian Constable (73 Posts)