All of the following are true about Scalenus anterior muscle:

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.