Extensor Carpi Radialis Longus
Forearm · Upper Limb
The extensor carpi radialis longus is one of the radial wrist extensors on the back of the forearm. It arises from the lateral supracondylar ridge of the humerus, just above the common extensor origin, and inserts on the base of the second metacarpal. It extends the wrist and abducts it (radial deviation), and it provides an important synergistic stabilisation of the wrist when the fingers are being flexed into a fist. It is supplied by the radial nerve (C6, C7).
Origin, Insertion, Action & Nerve
Origin
Lateral supracondylar ridge of humerus
Insertion
Base of 2nd metacarpal
Action
Extension and abduction (radial deviation) of wrist
Nerve
Radial nerve (C6, C7)
Attachments explained
The Extensor Carpi Radialis Longus is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Lateral supracondylar ridge of humerus
Insertion
Base of 2nd metacarpal
Action & function
When the Extensor Carpi Radialis Longus contracts, it produces the following movement: Extension and abduction (radial deviation) of wrist.
As part of the Forearm group of the Upper Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Extensor Carpi Radialis Longus receives its nerve supply from the Radial nerve (C6, C7). This nerve carries fibres from spinal segment(s) C6, C7.
Because a muscle can only contract when its nerve is intact, injury to the Radial nerve or to its spinal roots (C6, C7) can weaken or paralyse the Extensor Carpi Radialis Longus, impairing the movements it normally produces (extension and abduction (radial deviation) of wrist). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Extensor Carpi Radialis Longus (the OIANS method)
Decode the name for the action: it extends the wrist and, being radialis, abducts it toward the thumb side. Its origin high on the supracondylar ridge, just above the common extensor tendon, sets it slightly apart from its shorter twin and explains its longer, more oblique pull.
Fix its function with a purpose: it stabilises the wrist in extension when you clench a fist, so the finger flexors can work from a firm base. Grouping the radial wrist extensors together, and noting this one is supplied by the radial nerve trunk rather than its deep branch, keeps the pair straight.
Frequently asked questions
Where is the Extensor Carpi Radialis Longus located?
The Extensor Carpi Radialis Longus is a muscle of the Forearm group, located in the Upper Limb.
What is the origin of the Extensor Carpi Radialis Longus?
Lateral supracondylar ridge of humerus
What is the insertion of the Extensor Carpi Radialis Longus?
Base of 2nd metacarpal
What movements does the Extensor Carpi Radialis Longus produce?
Extension and abduction (radial deviation) of wrist
What nerve supplies the Extensor Carpi Radialis Longus?
Radial nerve (C6, C7)
Is the Extensor Carpi Radialis Longus free to study in OIANS?
Yes. The Extensor Carpi Radialis Longus is free in OIANS: its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory, and because it belongs to the Upper Limb it is also covered by the free Quiz and Flashcard decks. The other regions, the "All Muscles" deck, and the Progress and Explore tools are unlocked with a one-time Lifetime purchase.
Related muscles
Study the Extensor Carpi Radialis Longus
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