Anatomy of the radial nerve

It is a mixed nerve, the most voluminous and it deals mainly with the extension of the arm.

The radial nerve (C6-T1) originates from the dividing branch of the posterior bundle.

• It runs in the posteroinferior part of the axillary fossa with a downward and outward oblique path
• It travels to the posterior compartment of the arm and crosses the inferior axillary space where it is accompanied by the deep brachial artery.
• It then travels obliquely outward and downward in the radial nerve groove to the lower end of this groove.
• It passes back into the anterior compartment by crossing the lateral inter-muscular septum at the level of the arch of the vastus lateralis muscle.
  It goes into the lateral bicipital groove to divide into 2 terminals.

In the back of the arm

• Superior nerve of the vastus medialis
• Nerve of the long triceps
• Vastus lateralis nerve
• Post cutaneous nerve of the arm

After the radial groove

• Post cutaneous nerve of the forearm (originates in the groove)
• Outer skin vein
• Lower nerve of the vastus medialis and anconeus

In the external bicipital groove

• Nerve of the radial brachio
• Nerve of the LERC and CERC

Origin: originates in the lateral bicipital gutter

Course: descends downward into the aponeurosis of the brachio radial muscle and runs laterally along the radial artery. It becomes dorsal and subcutaneous in the lower ¼ of the forearm

Terminations: it ends in 3 branches above the radial styloid:

• Lateral branch: proper digital nerve lateral to the thumb and thenaric branch
• Middle branch: common dorsal nerves of the^2nd and^3rd space
• Medial branch: nerve communicating with the ulnar nerve

Origin: originates in the lateral bicipital gutter

Path: runs backwards and downwards to pass under an arch that joins the CERC and the aponeurosis of the flexors, then it passes into the 2 heads of the supinator muscle, giving collaterals. It then travels between the 2 muscle planes of the posterior compartment.

Termination: it divides into 2 nerves:

• One for the innervation of all the muscles of the deep layer
• Another one innervating all the muscles of the superficial layer of the posterior lodge

• Forearm: all the posterior and lateral lodge
• Arms: all the posterior lodge

• Arm: posterior and posterolateral aspect of the elbow
• Forearm: posterior face
• Hand: dorsal side outside the axis of the third except for P2 and P3

• Root canal syndrome in the lower axillary space
• Root canal syndrome in the sulcus and especially in the vastus lateralis band
• Root canal syndrome under the aponeurotic expansion between the CERC and the flexor aponeurosis
• Root canal syndrome between the 2 chiefs of the supinator muscle

Marie Messager
Osteopath in Versailles Chantiers
78 - Yvelines