Anconeus epitrochlearis muscle

Last revised by Daniel J Bell on 28 Aug 2021

The anconeus epitrochlearis muscle is an accessory muscle of the upper limb at the medial aspect of the elbow. It is also known as the accessory anconeus muscle or epitrochleoanconeus muscle and should not be confused with the anconeus muscle which is present at the lateral aspect of the elbow

The muscle may be unilateral but has been found to be bilateral in one of four patients with cubital tunnel syndrome 2. It is present in ~15% (range 3-28%) of the population 3

It can be asymptomatic or symptomatic when there is compression of the ulnar nerve within the cubital tunnel, leading to ulnar neuritis.

  • medial epicondyle (inferior surface)
  • olecranon (medial cortex)

The anconeus epitrochlearis muscle contributes to the roof of the cubital tunnel when present, running superficial to the ulnar nerve in the posteromedial aspect of the elbow.

Thin hypoechoic mass superficial to the ulnar nerve. May also demonstrate underlying ulnar nerve changes (thickening and edema) suggestive of cubital tunnel syndrome 4.

Axial MR images may demonstrate a mass superficial to the cubital tunnel, where there should normally only be fat.

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Cases and figures

  • Case 1
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  • Case 2: on ultrasound
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  • Case 3: bilateral anconeus epitrochlearis
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  • Case 4: cubital tunnel syndrome due to anconeus epitrochlearis
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