Extensor digitorum brevis manus muscle
Updates to Article Attributes
The extensor digitorum brevis manus (EDBM) muscle is an accessory muscle in the hand and is a normal anatomical variant.
Summary
origin: distal radius and posterior radiocarpal ligament
insertion: extensor hood of 2nd or 3rd digits (variable)
innervation: posterior interosseous nerve
action: extension of the digits
Epidemiology
First described by Albinus in 1734, itIt is thought to be present in ~3% of the population 1. It can be bilateral in up to half of cases.
Gross anatomy
The EDBM muscle lies along the ulnar side of the extensor tendon of the 2nd digit (usually fourth wrist compartment 5). It commonly arises at the distal end of the radius and posterior radiocarpal ligament to insert most commonly on the 2nd digit. However, insertion can also be seen on the 3rd, 4th, or 5th digits, as well as multiple insertions on more than one digit.
Arterial supply
Innervation
Clinical presentation
The muscle is usually painless although rarely it can present as a painful mass over the dorsal aspect of the hand. Occasionally it may be associated with exercise-induced pain or tenosynovitis of the extensor tendons.
Radiographic features
Plain radiograph
Can be normal.
Ultrasound
Sonography may reveal a soft-tissue mass with muscle echotexture; in real time, it usually undergoes morphologic changes during active finger extension.
MRI
Signal characteristics include:
T1/T2/PD: isointense to muscle on all sequences
C+ (Gd): no enhancement in uncomplicated cases (e.g. unless there is inflammation)
History and etymology
The muscle was first described by Bernhard Albinus (1697-1770), German-born Dutch anatomist, who discovered the muscle in 1734 and initially named it the extensor brevis digiti indicis vel medii 8,9.
-</ul><h4>Epidemiology</h4><p>First described by Albinus in 1734, it is thought to be present in ~3% of the population <sup>1</sup>. It can be bilateral in up to half of cases.</p><h4>Gross anatomy</h4><p>The EDBM muscle lies along the ulnar side of the extensor tendon of the 2<sup>nd</sup> digit (usually fourth wrist compartment <sup>5</sup>). It commonly arises at the distal end of the radius and posterior radiocarpal ligament to insert most commonly on the 2<sup>nd</sup> digit. However, insertion can also be seen on the 3<sup>rd</sup>, 4<sup>th</sup>, or 5<sup>th</sup> digits, as well as multiple insertions on more than one digit. </p><h4>Arterial supply</h4><ul><li><p><a href="/articles/anterior-interosseous-artery" title="Anterior interosseous artery">anterior interosseous artery</a><sup> 7</sup></p></li></ul><h4>Innervation</h4><ul><li><p><a href="/articles/posterior-interosseous-nerve">posterior interosseous nerve</a><sup> 7</sup></p></li></ul><h4>Clinical presentation</h4><p>The muscle is usually painless although rarely it can present as a painful mass over the dorsal aspect of the hand. Occasionally it may be associated with exercise-induced pain or tenosynovitis of the extensor tendons.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Can be normal.</p><h5>Ultrasound</h5><p>Sonography may reveal a soft-tissue mass with muscle echotexture; in real time, it usually undergoes morphologic changes during active finger extension.</p><h5>MRI</h5><p>Signal characteristics include:</p><ul>- +</ul><h4>Epidemiology</h4><p>It is thought to be present in ~3% of the population <sup>1</sup>. It can be bilateral in up to half of cases.</p><h4>Gross anatomy</h4><p>The EDBM muscle lies along the ulnar side of the extensor tendon of the 2<sup>nd</sup> digit (usually fourth wrist compartment <sup>5</sup>). It commonly arises at the distal end of the radius and posterior radiocarpal ligament to insert most commonly on the 2<sup>nd</sup> digit. However, insertion can also be seen on the 3<sup>rd</sup>, 4<sup>th</sup>, or 5<sup>th</sup> digits, as well as multiple insertions on more than one digit. </p><h4>Arterial supply</h4><ul><li><p><a href="/articles/anterior-interosseous-artery" title="Anterior interosseous artery">anterior interosseous artery</a><sup> 7</sup></p></li></ul><h4>Innervation</h4><ul><li><p><a href="/articles/posterior-interosseous-nerve">posterior interosseous nerve</a><sup> 7</sup></p></li></ul><h4>Clinical presentation</h4><p>The muscle is usually painless although rarely it can present as a painful mass over the dorsal aspect of the hand. Occasionally it may be associated with exercise-induced pain or tenosynovitis of the extensor tendons.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Can be normal.</p><h5>Ultrasound</h5><p>Sonography may reveal a soft-tissue mass with muscle echotexture; in real time, it usually undergoes morphologic changes during active finger extension.</p><h5>MRI</h5><p>Signal characteristics include:</p><ul>
References changed:
- 1. Ouellette H, Thomas B, Torriani M. Using Dynamic Sonography to Diagnose Extensor Digitorum Brevis Manus. AJR Am J Roentgenol. 2003;181(5):1224-6. <a href="https://doi.org/10.2214/ajr.181.5.1811224">doi:10.2214/ajr.181.5.1811224</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/14573408">Pubmed</a>
- 2. Anderson M, Benedetti P, Walter J, Steinberg D. MR Appearance of the Extensor Digitorum Manus Brevis Muscle: A Pseudotumor of the Hand. AJR Am J Roentgenol. 1995;164(6):1477-9. <a href="https://doi.org/10.2214/ajr.164.6.7754896">doi:10.2214/ajr.164.6.7754896</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/7754896">Pubmed</a>
- 1. Ouellette H, Thomas BJ, Torriani M. Using dynamic sonography to diagnose extensor digitorum brevis manus. AJR Am J Roentgenol. 2003;181 (5): 1224-6. <a href="http://dx.doi.org/10.2214/ajr.181.5.1811224">doi:10.2214/ajr.181.5.1811224</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/14573408">Pubmed citation</a><span class="ref_v3"></span>
- 2. Anderson MW, Benedetti P, Walter J et-al. MR appearance of the extensor digitorum manus brevis muscle: a pseudotumor of the hand. AJR Am J Roentgenol. 1995;164 (6): 1477-9. <a href="http://dx.doi.org/10.2214/ajr.164.6.7754896">doi:10.2214/ajr.164.6.7754896</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/7754896">Pubmed citation</a><span class="ref_v3"></span>