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Radial muscles of the forearm: want to learn more about it?

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Radial muscles of the forearm

The radial musculature consists of three muscles located at the lateral forearm. They all run from or near the lateral epicondyle of the humerus to the wrist.

As their bellies and tendons lie superficially, they can be easily palpated.

Radial group of posterior compartment muscles of forearm
Brachioradialis

Origin: Lateral supracondylar ridge of humerus and lateral intermuscular septum of arm

Insertion: (Proximal to) Styloid process of radius

Innervation: Radial Nerve (C5, C6)

Action: Elbow joint: Forearm flexion (when semi pronated)

Extensor carpi radialis longus

Origin: Lateral supracondylar ridge of humerus and lateral intermuscular septum of arm

Insertion: Posterior aspect of base of metacarpal bone 2

Innervation: Radial Nerve (C6, C7)

Action: Wrist joints: Hand extension, hand abduction (radial deviation)

Extensor carpi radialis brevis

Origin: Lateral epicondyle of humerus (common extensor tendon)

Insertion: Posterior aspect of base of metacarpal bone 3

Innervation: Radial Nerve (C7, C8)

Action: Wrist joints: Hand extension, hand abduction (radial deviation)

Anatomy and supply

The three radial muscles are described below. 

Extensor carpi radialis longus & brevis (dorsal view)

Brachioradialis muscle

The brachioradialis muscle originates at the lateral supracondylar ridge (between the brachialis and lateral head of the triceps) and the lateral intermuscular septum of the humerus and inserts proximal to the styloid process of the radius. This powerful muscle is mainly responsible for the lateral contour of the elbow and forearm. It flexes the forearm arm at the elbow joint, optimally with the forearm in a semi-pronated position.

Extensor carpi radialis longus

The ECRL has its origin slightly below at the lateral supracondylar ridge of the humerus and inserts distally at the posterior side of the base of the second metacarpal bone. The majority of this muscle lies underneath the brachioradialis.

Extensor carpi radialis brevis

The ECRB arises from the common extensor tendon of the superficial extensors at the lateral epicondyle of the humerus and attaches to the posterior side of the base of the third metacarpal bone.

Innervation

Radial nerve (ventral view)

All radial muscles are supplied by the radial nerve (C5-C8) which courses between the brachioradialis and brachialis to the elbow and there divides into a deep branch and a superficial branch at the height of the radial head.

The superficial branch uses the brachioradialis as a guiding structure to reach the wrist joint and arrives at the dorsum of the hand.

In contrast, the deep branch penetrates the supinator muscle and continues to the extensors of the forearm. It is important to notice that the branches supplying the brachioradialis and extensor carpi radialis longus branch off before the division of the radial nerve, whereas the nerve supplying the extensor carpi radialis brevis, the posterior interosseus nerve, arises just after the division.

Function

The radial musculature supports movements of the elbow, hand and radioulnar joints.

Brachioradialis (pronated forearm)
  • Brachioradialis is a powerful flexor of the elbow, acting most strongly with the forearm in semipronation.
Extensor carpi radialis longus (dorsal view)
  • In contrast, both the extensor carpi radialis longus and brevis are rather poor flexors of the elbow. Their main function is the extension and abduction (radial deviation) of the wrist joint. 
Extensor carpi radialis brevis (dorsal view)

Radial muscles of the forearm: want to learn more about it?

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