The thumb extensor tendons are maintained in a central position at the metacarpophalangeal joint
level by radial and ulnar attachments to the Sagittal bands.
At this level, the extensor pollicis brevis
lies radial to the extensor pollicis longus
and attaches to the dorsal base of the proximal phalanx.
Radial and ulnar tendon slips from the Abductor Pollicis Brevis
and the Adductor Pollicis
muscles, respectively, and the extensor pollicis longus
join the extensor hood to form the Terminal tendon.
This crosses the dorsal surface of the interphalangeal joint
to attach to the dorsal base of the distal phalanx.
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