Anconeus
Forearm · Upper Limb
The anconeus is a small triangular muscle at the back of the elbow, essentially continuous with the triceps. It arises from the lateral epicondyle of the humerus and inserts onto the lateral surface of the olecranon and the posterior surface of the proximal ulna. It assists the triceps in extending the elbow and helps stabilise the elbow joint, and it is thought to steady the ulna during pronation and supination. Like the triceps it is supplied by the radial nerve (C7, C8).
Origin, Insertion, Action & Nerve
Origin
Lateral epicondyle of humerus
Insertion
Lateral surface of olecranon and posterior surface of proximal ulna
Action
Assists triceps in extension of elbow; stabilizes elbow joint
Nerve
Radial nerve (C7, C8)
Attachments explained
The Anconeus 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
Insertion
Lateral surface of olecranon and posterior surface of proximal ulna
Action & function
When the Anconeus contracts, it produces the following movements: Assists triceps in extension of elbow; stabilizes elbow joint.
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 Anconeus receives its nerve supply from the Radial nerve (C7, C8). This nerve carries fibres from spinal segment(s) C7, C8.
Because a muscle can only contract when its nerve is intact, injury to the Radial nerve or to its spinal roots (C7, C8) can weaken or paralyse the Anconeus, impairing the movements it normally produces (assists triceps in extension of elbow). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Anconeus (the OIANS method)
Treat the anconeus as a small extension of the triceps rather than a separate concept. It shares the same job, assisting elbow extension, and the same radial nerve supply, so once you know the triceps you already know most of the anconeus. Its origin on the lateral epicondyle and insertion on the proximal ulna simply place it across the back of the elbow joint.
The one distinctive idea to add is stabilisation: the anconeus is thought to steady the ulna during pronation and supination and to support the elbow joint. Holding it in mind as the triceps' little stabilising helper is enough to recall it without confusion.
Frequently asked questions
Where is the Anconeus located?
The Anconeus is a muscle of the Forearm group, located in the Upper Limb.
What is the origin of the Anconeus?
Lateral epicondyle of humerus
What is the insertion of the Anconeus?
Lateral surface of olecranon and posterior surface of proximal ulna
What movements does the Anconeus produce?
Assists triceps in extension of elbow; stabilizes elbow joint
What nerve supplies the Anconeus?
Radial nerve (C7, C8)
Is the Anconeus free to study in OIANS?
Yes. The Anconeus 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 Anconeus
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