Anatomy study note · Upper limb
Radial nerve
The largest branch of the brachial plexus, from the posterior cord (C5–T1). It supplies all the extensor muscles of the arm and forearm.
Key points
- Posterior cord, C5–T1; all extensors.
- Spiral groove with profunda brachii → shaft fracture → wristdrop.
- Deep branch pierces supinator → posterior interosseous nerve.
- Superficial branch: sensory to the lateral dorsum of the hand.
- Deep-branch lesion: no wristdrop (ECRL spared).
- Upper limb nerves: C4–T2 segments; lower limb: L2–S2.
- Ventral root: basal-lamina neurons. Dorsal root: neural-crest ganglion cells.
- Nerve: epineurium → perineurium (blood–nerve barrier) → endoneurium.
- Cut nerve: Wallerian degeneration; regrows 0.5–3 mm/day.
The full note in the atlas also covers
Course · Branches · Histology · Development · Clinical notes
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Written from
- Snell’s Clinical Anatomy by Regions, 10th ed., ch. 3, PDF pp. 350–353, 357–364
- Inderbir Singh’s Human Embryology, ch. 17, PDF pp. 318, 321, 323–325; ch. 10, PDF pp. 143–144
- BRS Cell Biology & Histology, 7th ed., ch. 9, PDF pp. 163–166, 171–172
More from the upper limb
- Radioulnar joints and interosseous membrane
- Radius
- Rhomboid major
- Rhomboid minor
- Scapula
- Serratus anterior
- Shoulder joint
- Sternoclavicular joint
- Subclavius
- Subscapular nerves
- Subscapularis
- Supinator
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