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
Exposure of left subclan aery by supraclavicular approach does not require cutting of ? 
Select and explain. 
A. Sternocleidomastoid, B. Scalenus anterior, C. Scalenus medius, D. Omohyoid
C: Scalenus medius
Answer: C: Scalenus medius 
Explanation: Scalenus medius lies posterior to the subclan aery and thus need not be divided to expose the aery. Whereas, sternocleidomastoid & scalenus anterior lie anteriorly and omohyoid lies superiorly and thus are cut during exposure of the subclan aery.