Supinator
Forearm · Upper Limb
Supinator belongs to the Forearm group of the Upper Limb. Originating at Lateral epicondyle of humerus, radial collateral and anular ligaments, supinator crest of ulna, it inserts at Lateral, posterior, and anterior surfaces of proximal radius. Its chief action is that it supination of forearm. Its nerve supply is the Deep branch of radial nerve (posterior interosseous) (C6, C7).
Origin, Insertion, Action & Nerve
Origin
Lateral epicondyle of humerus, radial collateral and anular ligaments, supinator crest of ulna
Insertion
Lateral, posterior, and anterior surfaces of proximal radius
Action
Supination of forearm
Nerve
Deep branch of radial nerve (posterior interosseous) (C6, C7)
Attachments explained
The Supinator 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 epicondyle of humerus, radial collateral and anular ligaments, supinator crest of ulna
Insertion
Lateral, posterior, and anterior surfaces of proximal radius
Action & function
When the Supinator contracts, it produces the following movement: Supination of forearm.
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 Supinator receives its nerve supply from the Deep branch of radial nerve (posterior interosseous) (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 Deep branch of radial nerve or to its spinal roots (C6, C7) can weaken or paralyse the Supinator, impairing the movements it normally produces (supination of forearm). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Supinator (the OIANS method)
OIANS stands for Origin, Insertion, Action and Nerve, the four facts that uniquely define every skeletal muscle. To learn the Supinator, work through them in order: picture its origin, trace the muscle to its insertion, reason out the action that shortening between those two points must create, then add the nerve that drives it.
Most students remember the Supinator fastest by linking its action back to its attachments rather than memorising each fact in isolation. Once the origin and insertion make sense, the action usually follows logically.
Supinator quick facts
- Region
- Upper Limb
- Group
- Forearm
- Origin
- Lateral epicondyle of humerus, radial collateral and anular ligaments, supinator crest of ulna
- Insertion
- Lateral, posterior, and anterior surfaces of proximal radius
- Action
- Supination of forearm
- Nerve
- Deep branch of radial nerve (posterior interosseous) (C6, C7)
- Spinal roots
- C6, C7
Frequently asked questions
Where is the Supinator located?
The Supinator is a muscle of the Forearm group, located in the Upper Limb.
What is the origin of the Supinator?
Lateral epicondyle of humerus, radial collateral and anular ligaments, supinator crest of ulna
What is the insertion of the Supinator?
Lateral, posterior, and anterior surfaces of proximal radius
What movements does the Supinator produce?
Supination of forearm
What nerve supplies the Supinator?
Deep branch of radial nerve (posterior interosseous) (C6, C7)
Is the Supinator free to study in OIANS?
Yes. The Supinator 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 Supinator
Test yourself on Upper Limb muscles with interactive quizzes and flashcards in the free OIANS app.
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