Extensor expansion

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Extensor expansion
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Extensor expansion covers the tendon of extensor digitorum tendons over the proximal phalanges
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.

Contents

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

The expansion soon divides into three bands:

Function

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]

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Extrinsic extensor muscles of the hand

The extrinsic extensor muscles of the hand are located in the back of the forearm and have long tendons connecting them to bones in the hand, where they exert their action. Extrinsic denotes their location outside the hand. Extensor denotes their action which is to extend, or open flat, joints in the hand. They include the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor digitorum (ED), extensor digiti minimi (EDM), extensor carpi ulnaris (ECU), abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and extensor indicis (EI).

Muscles of the thumb

The muscles of the thumb are nine skeletal muscles located in the hand and forearm. The muscles allow for flexion, extension, adduction, abduction and opposition of the thumb. The muscles acting on the thumb can be divided into two groups: The extrinsic hand muscles, with their muscle bellies located in the forearm, and the intrinsic hand muscles, with their muscles bellies located in the hand proper.

References

  1. 1 2 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
  2. "eMedicine - Hand, Tendon Lacerations: Extensors : Article by D Glynn Bolitho, MD, PhD, FACS" . Retrieved 2008-01-20.[ failed verification ]
  3. Kyung Won, PhD. Chung (2005). Gross Anatomy (Board Review). Hagerstown, MD: Lippincott Williams & Wilkins. p. 43. ISBN   0-7817-5309-0.