Skip to main content
OrthoVellum
Knowledge Hub

Study

  • Topics
  • MCQs
  • ISAWE
  • Operative Surgery
  • Flashcards

Company

  • About Us
  • Editorial Policy
  • Contact
  • FAQ
  • Blog

Legal

  • Terms of Service
  • Privacy Policy
  • Cookie Policy
  • Medical Disclaimer
  • Copyright & DMCA
  • Refund Policy

Support

  • Help Center
  • Accessibility
  • Report an Issue
OrthoVellum

© 2026 OrthoVellum. For educational purposes only.

Not affiliated with the Royal Australasian College of Surgeons.

Hand & Upper Limb
intermediate
X-Type

Posterior Interosseous Nerve Syndrome

Peripheral Nerve Disorders

A 48-year-old man presents with 3 months of progressive weakness in extending his fingers and thumb. He denies pain or sensory changes. On examination, he cannot extend the MCP joints of his fingers or extend and abduct his thumb. Wrist extension is present but with radial deviation. The extensor carpi radialis brevis and longus are functioning. Regarding posterior interosseous nerve (PIN) syndrome:

Mark each as TRUE or FALSE

A

The posterior interosseous nerve (PIN) is the deep motor branch of the radial nerve that arises at t...

B

PIN syndrome causes weakness of finger MCP extension (EDC, EIP), thumb extension (EPL, EPB), thumb a...

C

PIN syndrome causes sensory loss over the dorsal hand and thumb web space; the brachioradialis and E...

D

Causes of PIN compression include the arcade of Frohse, fibrous bands within the supinator, the leas...

E

Finger and thumb IP extension is preserved in PIN syndrome because the lumbricals and interossei (me...

Answer the questions to see explanations

Click T (True) or F (False) for each option