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Extensor Carpi Radialis Longus

The extensor carpi radialis longus muscle emerges from the lateral epicondyle of the humerus and the distal part of the supraepicondylar rim; its tendon enters on the dorsal side of the base of metacarpal II.

In proximal areas, it is deep to the brachioradialis muscle. The wrist is expanded and abducted by the extensor carpi radialis longus muscle.

Extensor Carpi Radialis Longus

Extensor Carpi Radialis Longus

Structure

The extensor carpi radialis longus has a long, slim, flat tendon that proceeds down the outer side of the radius, together with the tendon of the extensor carpi radialis brevis and of a short, flat, fleshy muscle midriff which terminates at the upper third of the forearm. The tendon subsequently passes down the back side of completion of the radius in its own bony notch.On the lower half of the forearm, the tendons of both of these radial wrist extensors, passing under the abductor pollicis longus and extensor pollicis brevis, might look like a slim elevated rim whenever the wrist is expanded. They produce a small changing plane in between the back of the wrist and the back of the hand when the wrist is expanded after these tendons exit the distal end of the radius. At their superior ends, the extensor carpi radialis longus and brachioradialis start side by side at their origin; however the midriff of the extensor carpi radialis longus is quickly partly covered by the midriff of the brachioradialis as they come down.

Extensor Carpi Radialis Longus

Extensor Carpi Radialis Longus

These two muscle midriffs generally mix together into a single kind when the elbow is expanded there might be a minor separation if the wrist is likewise expanded. The midriff of the extensor carpi radialis longus is at its smallest when the elbow joint is bent to 90° with the wrist expanded and ends up being a reasonably protrusive, short, triangular relief when tensed, rather different from the brachioradialis.

Near the upper end of the forearm an indentation creates where the midriff of the extensor carpi radialis longus connects to its tendon. This midriff is significantly smaller compared to the midriff of the brachioradialis.

Insertion

  1. Below the abductor pollicis longus and extensor pollicis brevis, the fibers terminate at the upper third of the forearm in a flat tendon that follows the lateral border of the radius.
  2. It then moves below the dorsal carpal ligament, where it is located on a notch on the back of the radius common to it and the extensor carpi radialis brevis, instantly behind the styloid process.
  3. One of the three muscles of the radial forearm group, it at first lies beside the brachioradialis, however ends up being primarily tendon early on.
  4. This tendon proceeds into the second tendon chamber along with the latter muscle moving in between the brachioradialis and the extensor carpi radialis brevis.
  5. It is embedded within the dorsal side of the base of the second metacarpal bone, on its radial side.

Nerve Supply

It is innervated by the radial nerve prior to the nerve splits into superficial and deep sections.

Action

  • This muscle has a number of functions.
  • It bends an individual’s wrist in manner in which their thumb is getting moved to the inner side of forearm and radius, specifically which indicates its primary action is a radial deviation of the hand.
  • It expands and supports the latter throughout grasping motions and in this manner avoids it from flexion. Furthermore, together with the other extensors of wrist.

Clinical Significance

  • It can create pain at the lateral aspect of an individual’s elbow, if extensor carpi radialis longus muscle is too tight or consists of sensitive and/or trigger points. In this way it simulates tennis elbow pain.
  • Furthermore an individual can experience pain all the way down their forearm and to the behind of hand.
  • Another typical sign is a poor and painful grip, which also can make them drop lightweight things
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