Anatomical variants · USMLE Step 1

A patient has a cervical rib arising from C7. This variant increases risk for which condition?

  1. Thoracic outlet syndrome
  2. Carpal tunnel syndrome
  3. Cubital tunnel syndrome
  4. Popliteal artery entrapment
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Correct answer: Thoracic outlet syndrome

A cervical rib may compress the brachial plexus or subclavian vessels, causing thoracic outlet symptoms. It is a clinically significant variant.

Difficulty: Medium Question 18 of 20

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