Hand · Interactive 3D

Wrist cross-section

A transverse section through the distal forearm just above the wrist: radius and ulna, pronator quadratus, the flexor tendons and median nerve on the palmar side and the extensor compartments dorsally.

Interactive — drag to rotate

What to look at

1Orbit to look straight into the cut face — the two bones sit in the middle with pronator quadratus draped across their palmar surface.
2Palmar to that lie the flexor tendons (FDS, FDP, FPL) with the median nerve among them — the contents that continue into the carpal tunnel.
3Dorsally, the extensor tendons are grouped into the six extensor compartments under the retinaculum.
4The radial artery runs on the thumb side between flexor carpi radialis and brachioradialis — where the radial forearm flap pedicle is found.

Hotspots

1Radius — The larger distal bone on the thumb side; Lister’s tubercle separates the second and third extensor compartments on its dorsum.
2Ulna — Distal ulna and the triangular fibrocartilage complex beyond it; the ulnar nerve and artery run on this side.
3Pronator quadratus — Deepest layer of the palmar forearm, between the bones and the deep flexors.
4Flexor tendons and median nerve — FDS, FDP and FPL with the median nerve — nine tendons and the nerve pass on into the carpal tunnel.
5Extensor compartments — Six compartments under the extensor retinaculum: APL/EPB, ECRL/ECRB, EPL, EDC/EIP, EDM, ECU.

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Flexor tendon injuries: zones, pulleys, repair and rehabilitation

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