This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
All of the following are true about Scalenus anterior muscle: 
Select and explain. 
A. It is attached to the tubercle of second Rib, B. It is anterior to the transverse cervical aery., C. It is pierced by the phrenic nerve., D. It separates the subclan vein from the subclan aery
D: It separates the subclan vein from the subclan aery
Answer: D: It separates the subclan vein from the subclan aery 
Explanation: It separates the subclan vein from the subclan aery The scalene muscles are a group of three pairs of muscles in the lateral neck, namely the scalenus anterior, scalenus medius, and scalenus posterior. These extend from the transverse processes of the cervical veebrae to the first two ribs. Thus they help to either elevate the ribs of bend the neck laterally.Of these scalenus medius is the largest and scalenus posterior is the smallest.