Anatomy study note · Upper limb

Extensor carpi radialis longus

A lateral-compartment muscle supplied by the main radial nerve, which is why a deep-branch lesion does not cause wristdrop.

Key points

• Lateral supracondylar ridge → base of MC2.
• Radial nerve (main trunk).
• Wrist extension + abduction.
• Spared in deep-branch lesions → no wristdrop.
• Limb muscles: in situ from limb-bud mesenchyme.
• Upper limb bud C4–T2; lower limb bud L2–S2.
• Skeletal muscle: multinucleated, peripheral nuclei, striated.
• Epimysium → perimysium → endomysium.

The full note in the atlas also covers

Origin · Insertion · Action · Nerve supply · Histology · Development

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Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 3, PDF pp. 309, 350–353
• Inderbir Singh’s Human Embryology, ch. 7, PDF p. 109; ch. 10, PDF pp. 142–145
• BRS Cell Biology & Histology, 7th ed., ch. 8, PDF pp. 135–144

More from the upper limb

• Extensor carpi ulnaris
• Extensor digiti minimi
• Extensor digitorum
• Extensor indicis
• Extensor pollicis brevis
• Extensor pollicis longus
• Extensor retinaculum of the wrist
• Flexor carpi radialis
• Flexor carpi ulnaris
• Flexor digitorum profundus
• Flexor digitorum superficialis
• Flexor pollicis longus

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