Review Question - QID 3023

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Humeral Shaft Fractures Complications Radial nerve palsy QID: 3023 (OBQ09.210)

QID 3023 (Type "3023" in App Search)

A 32-year-old man presents to the emergency department with a humeral shaft fracture. He has wrist drop as well as impaired finger and thumb extension. Which motor function would be expected to recover last?

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Elbow extension

23/1790

Forearm supination

26/1790

Wrist extension in radial deviation

132/1790

Middle finger MCP extension

10%

187/1790

Index finger MCP hyperextension

79%

1415/1790

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The patient is presenting with radial nerve palsy secondary to his humerus fracture. Motor recovery proceeds in a proximal to distal direction.

Abrams et al detailed the order of innervation of the radial nerve and found the following order (proximal to distal): brachioradialis, extensor carpi radialis longus, supinator, extensor carpi radialis brevis, extensor digitorum communis, extensor carpi ulnaris, extensor digiti quinti, abductor pollicis longus, extensor policis longus, extensor policis brevis, and extensor indicis proprius.

Branovacki et al found a slightly different pattern: brachioradialis, extensor carpi radialis longus, sensory, extensor carpi radialis brevis, supinator, extensor digitorum/extensor carpi ulnaris, extensor digiti minimi, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus and extensor indicis proprius.

While both extensor digitorum and extensor indicis proprius extend the index finger MCP joint, only extensor indicis proprius hyperextends the index finger past neutral.