In the forearm and hand, there are three crucial nerves which deliver information about movement from the central nervous system (CNS), and deliver information about feeling and position back to the CNS. One that we will discuss is the radial nerve which is essential for you to give a thumbs up, extend your wrist and fingers to pick up a cup, and turn your palm over, e.g., to collect your change at the checkout. It also carries information back to the CNS about feeling and joint position.

The radial tunnel describes an area roughly 5cm in length where the radial nerve splits into two segments, and the deeper segment passes between several structures forming the ‘tunnel.' This tunnel can be a problem area for compression of the nerve.  As a result the nerve cannot transmit all of the signals – like standing a garden hose and seeing the flow of water become a dribble.

Here is an image showing the radial nerve as it passes over the elbow.  (Image courtesy of www.sportsphysiotherapy.com.au)

Radial-Tunnel-Syndrome-Anatomy-Sports-Physiotherapy

The tunnel starts proximally (closest to the shoulder) in front of the radiocapitellar joint within the elbow, and the nerve rests on the radiocapitellar joint capsule. The floor is formed by the surface of the radiocapitellar joint capsule, then by the deep layer of the supinator muscle, which has deep and superficial heads. The medial wall (inner) is formed by the brachialis muscle and the biceps tendon. The lateral wall (outer wall, furthest from the body) is formed by the brachioradialis, extensor carpi radialis longus and extensor carpi radialis brevis muscles.  It finishes distally (furthest from the shoulder) at the distal edge of the supinator muscle.

Why is this important?  Because any increased tension on the radial nerve as it passes through it's tunnel can cause distruption to the role of the nerve, and in these cases, create pain and aching along the nerve in the forearm.  If you have a dull heavy ache in your forearm, come and see us and we can assess if your radial tunnel is in a healthy state or not.

Written by Louise Brown, Senior Occupational Therapist