Anatomy The key to the root of the neck is the scalenus anterior muscle. Which among the following is TRUE about scalenus anterior? A Not Pierced by phrenic nerve B Attached to scalene tubercle on 2nd rib C Separates subclan aery from subclan vein D Pierced by phrenic nerve 💡 Explanation The key to the root of the neck is the scalenus anterior muscle. Which among the following is TRUE about scalenus anterior? ✓ Correct Answer: B. Attached to scalene tubercle on 2nd rib