https://teachmeanatomy.info/upper-limb/nerves/radial-nerve/ has a good description

• Posterior approach
  • Triceps splitting
    • Identify heads proximally and can split them
  • Distal triceps sparing
    • free up either side of the triceps tendon
• Anterolateral (proximal to distal humerus)
  • deltopectoral interval to between deltoid and biceps to between biceps and brachioradialis
    • see AO Reference
• Lateral (distal 2/3)
  • Essentially like a lateral arm flap
  • keeping lateral intermuscular septum posteriorly
  • see AO reference

• Crosses humerus posteriorly at spiral groove 14-29 cm proximal to distal humerus

• created 2021-06-06