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Anconeus muscle: want to learn more about it?

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Anconeus muscle

Anconeus muscle (musculus anconeus)

The anconeus is a small, triangular muscle of the upper arm. It is located at the posterior aspect of the elbow, extending from the distal humerus to the proximal ulna.

The anconeus muscle belongs to the superficial extensor compartment, along with the brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi and extensor carpi ulnaris muscles.

The anconeus muscle assists in the extension of the forearm and provides support for both the dorsal capsule of the humeroulnar joint and the ulna itself. 

In this article, we will discuss the anatomy and function of the anconeus muscle. 

Key facts about the anconeus muscle
Origin

Lateral epicondyle of humerus

Insertion Lateral surface of olecranon
Action Assists in forearm extension at the elbow joint;
Stabilization of elbow joint
Innervation Radial nerve (C7-C8)
Blood supply Posterior interosseous recurrent artery

Origin and insertion

The anconeus muscle originates by a tendon on the dorsal aspect of the lateral epicondyle of the humerus, just proximal to the common extensor tendon. Its tendon lies deep to the muscle belly of extensor carpi radialis longus and is partially attached to the dorsal capsule of the humeroulnar joint.

The anconeus tendon spreads out obliquely and medially into a wide muscle belly, and inserts at the lateral surface of the olecranon of the ulna and the adjoining posterior surface of the ulnar shaft. Some authors consider the anconeus as a continuation of the triceps brachii muscle, due to their fibers often being partially or completely blended together.

Due to its superficial location, the anconeus can be easily palpated at the lateral side of the forearm near the elbow, especially during pronation and supination movements.

Anconeus muscle seen in the extensor compartment of the forearm muscles in a cadaver.

Innervation

The anconeus innervation stems from a motor branch of the radial nerve, arising from root value C6-C8. The skin over the anconeus is supplied by T1 spinal nerve.

Blood supply

The anconeus muscle is supplied by the recurrent interosseous branch of the posterior interosseous artery, along with contributions from the small number of musculocutaneous perforators.

Function

Pronation of the forearm (Pronatio antebrachii)

Functionally, the anconeus is a continuation of the triceps brachii muscle, exhibiting the same action at the elbow. Thereby, its contraction leads to the extension of the forearm.

Due to its long attachment on the ulna, it is believed that the anconeus has the additional function of abducting the ulna, especially during pronation movements of the forearm. This action is essential for stabilizing the ulna and allowing the rotatory movement of the forearm in activities such as using a screwdriver.

Furthermore, the anconeus tenses the dorsal joint capsule of the humeroulnar joint, thus preventing damage during hyperextension of the forearm.

Need some extra help learning the anconeus muscle? Our upper extremity muscle anatomy chart lists the attachments, innervations and functions of this muscle and all of its neighbours. It's an essential revision tool!

Clinical relations

An anatomical variation of the anconeus is found in up to one third of all humans. Even though most are harmless, there is one variation which can be considered clinically relevant, namely the anconeus epitrochlearis muscle.

This variant of the anconeus muscle originates at the medial epicondyle of the humerus, thus crossing the ulnar groove of the bone. Since the ulnar nerve courses in this groove, in cases of hypertrophy (e.g. in weightlifters), the anconeus epitrochlearis can cause a compression of the ulnar nerve. This results in numbness of the ulnar side of the hand, the little and ring fingers, as well as pain in the elbow (cubital tunnel syndrome).

Anconeus muscle: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
  • Palastanga, N., & Soames, R. (2012). Anatomy and human movement: structure and function (6th ed.). Edinburgh: Churchill Livingstone.
  • Standring, S. (2016). Gray's Anatomy (41tst ed.). Edinburgh: Elsevier Churchill Livingstone.
  • Netter, F. (2014). Atlas of Human Anatomy (6th ed.). Philadelphia, PA: Saunders.
  • Sinnatamby, C. S., & Last, R. J. (2011). Last's anatomy: Regional and applied. (12th edition). Edinburgh: Churchill Livingstone.
     

Illustrators:

  • Anconeus muscle (dorsal view) - Yousun Koh
  • Forearm extensors (cadaver dissection) - Prof. Carlos Suárez-Quian
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