Extensor expansion
An extensor expansion (extensor hood, dorsal expansion, dorsal hood, dorsal aponeurosis) is the special connective attachments by which the extensor tendons insert into the phalanges.
Extensor expansion | |
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![]() Extensor expansion covers the tendon of extensor digitorum tendons over the proximal phalanges | |
Anatomical terminology |
These flattened tendons (aponeurosis) of extensor muscles span the proximal and middle phalanges.[1]
At the distal end of the metacarpal, the extensor tendon will expand to form a hood, which covers the back and sides of the head of the metacarpal and the proximal phalanx.
Bands
The expansion soon divides into three bands:
- lateral bands pass on either side of the proximal phalanx and stretch all the way to the distal phalanx. The lumbricals of the hand, extensor indicis muscle,[2] dorsal interossei of the hand, and palmar interossei insert on these bands.
- A single median band passes down the middle of the finger along the back of the proximal phalanx, inserting into the base of the middle phalanx.
- A band known as the retinacular ligament runs obliquely along the middle phalanx, and connects the fibrous digital sheath on the anterior side of the phalanges to the extensor expansion.
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References
- "eMedicine - Hand, Tendon Lacerations: Extensors : Article by D Glynn Bolitho, MD, PhD, FACS". Retrieved 2008-01-20.
- Kyung Won, PhD. Chung (2005). Gross Anatomy (Board Review). Hagerstown, MD: Lippincott Williams & Wilkins. p. 43. ISBN 0-7817-5309-0.
External links
- lesson5musofpostforearm at The Anatomy Lesson by Wesley Norman (Georgetown University)
- Hand kinesiology at the University of Kansas Medical Center
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