Extensor digitorum brevis manus muscle
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View Yahya Baba's current disclosures- Extensor digitorum brevis manus (EDBM) muscles
The extensor digitorum brevis manus (EDBM) muscle is an accessory muscle in the hand and is a normal anatomical variant.
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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
It 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.
References
- 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. doi:10.2214/ajr.181.5.1811224 - Pubmed
- 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. doi:10.2214/ajr.164.6.7754896 - Pubmed
- 3. Bianchi S, Della Santa D, Glauser T et-al. Sonography of masses of the wrist and hand. AJR Am J Roentgenol. 2008;191 (6): 1767-75. doi:10.2214/AJR.07.4003 - Pubmed citation
- 4. Sookur PA, Naraghi AM, Bleakney RR et-al. Accessory muscles: anatomy, symptoms, and radiologic evaluation. Radiographics. 2008;28 (2): 481-99. Radiographics (full text) - doi:10.1148/rg.282075064 - Pubmed citation
- 5. Froelich JM, Bidgoli-Moghaddam M, Moran SL. Bilateral extensor digitorum brevis manus. Orthopedics. 2012;35 (9): e1431-3. doi:10.3928/01477447-20120822-34 - Pubmed citation
- 6. Rodríguez-Niedenführ M, Vázquez T, Golanó P et-al. Extensor digitorum brevis manus: anatomical, radiological and clinical relevance. A review. Clin Anat. 2002;15 (4): 286-92. Clin Anat (abstract) - doi:10.1002/ca.10027 - Pubmed citation
- 7. Shereen R, Loukas M, Tubbs RS. Extensor Digitorum Brevis Manus: A Comprehensive Review of this Variant Muscle of the Dorsal Hand. (2017) Cureus. 9 (8): e1568. doi:10.7759/cureus.1568 - Pubmed
- 8. Shereen R, Loukas M, Tubbs R. Extensor Digitorum Brevis Manus: A Comprehensive Review of This Variant Muscle of the Dorsal Hand. Cureus. 2017;9(8):e1568. doi:10.7759/cureus.1568 - Pubmed
- 9. Ranade A, Rai R, Prabhu L et al. Incidence of Extensor Digitorum Brevis Manus Muscle. Hand (N Y). 2008;3(4):320-3. doi:10.1007/s11552-008-9111-5 - Pubmed
- 10. Nakano M, Watanabe Y, Masutani M. A Case of Extensor Digitorum Brevis Manus. Dermatol Online J. 2003;9(5). doi:10.5070/d388k536fs
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