On the superior surface of the first rib, the anterior scalene muscle inserts at a roughened elevation. Which vessels pass relative to this insertion?

• A Subclavian artery and vein both anterior to the scalene tubercle
• B Subclavian vein anterior and subclavian artery posterior to the scalene tubercle ✓
• C Subclavian artery anterior and subclavian vein posterior to the scalene tubercle
• D Both vessels posterior to the scalene tubercle, in the interscalene triangle

Explanation

The anterior scalene inserts on the scalene tubercle of the first rib. The subclavian vein crosses the rib anterior to the insertion, while the subclavian artery and the roots of the brachial plexus pass posterior to it, through the interscalene triangle between the anterior and middle scalenes. This explains why a cervical rib or hypertrophied scalene compresses the artery and lower trunk nerves but spares the vein.

Reference: Gray's Anatomy for Students, 4th ed.

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Written and medically reviewed by the StethoPrep medical team.