Extensor expansion
| Extensor expansion | |
|---|---|
 Extensor expansion covers the tendon of extensor digitorum tendons over the proximal phalanges | |
| Identifiers | |
| TA98 | Lua error in Module:Wikidata at line 746: attempt to index field 'wikibase' (a nil value). |
| TH | {{#property:P1694}} |
| TE | {{#property:P1693}} |
| FMA | {{#property:P1402}} |
| Anatomical terminology [[[d:Lua error in Module:Wikidata at line 865: attempt to index field 'wikibase' (a nil value).|edit on Wikidata]]] | |
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 | edit source]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 | edit source]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
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External links
[edit | edit source]- lesson5musofpostforearm at The Anatomy Lesson by Wesley Norman (Georgetown University)
- Hand kinesiology at the University of Kansas Medical Center
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