Extensor expansion
| Extensor expansion | |
|---|---|
 Extensor expansion covers the tendon of extensor digitorum tendons over the proximal phalanges | |
| TA2 | 2502 |
| Anatomical terminology | |
An extensor expansion (extensor hood,[1] dorsal expansion, dorsal hood, dorsal aponeurosis[citation needed]) is the special connective attachments by which the extensor tendons insert into the phalanges.
These flattened tendons (aponeurosis) of extensor muscles span the proximal and middle phalanges.[2]
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
[edit]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,[3] 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.
Function
[edit]The extensor expansion allows for contractile forces from the extensor compartment muscles to be transferred to the phalanges. It also balances the forces across the phalanges.[1]
References
[edit]- ^ a b Blankenbaker, Donna G.; Davis, Kirkland W.; Sonin, Andrew; Crim, Julia R., eds. (2016-01-01), "Extensor Tendon Injury, Wrist and Fingers", Diagnostic Imaging: Musculoskeletal Trauma (Second Edition), Diagnostic Imaging, Elsevier, pp. 468–473, doi:10.1016/b978-0-323-39253-2.50118-x, ISBN 978-0-323-39253-2, retrieved 2021-01-04
- ^ "eMedicine - Hand, Tendon Lacerations: Extensors : Article by D Glynn Bolitho, MD, PhD, FACS". Retrieved 2008-01-20.[failed verification]
- ^ Kyung Won, PhD. Chung (2005). Gross Anatomy (Board Review). Hagerstown, MD: Lippincott Williams & Wilkins. p. 43. ISBN 0-7817-5309-0.
External links
[edit]- lesson5musofpostforearm at The Anatomy Lesson by Wesley Norman (Georgetown University)
- Hand kinesiology at the University of Kansas Medical Center
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