The roots and trunks enter the posterior triangle of the neck by passing: (A) Between the anterior scalene and middle scalene muscles, (B) Between the middle scalene and posterior scalene muscles, (C) Behind subclavius muscle, (D) Posterior and inferior subclavian Artery
Answer is A. The roots and trunks enter the posterior triangle of the neck by passing between the anterior scalene and middle scalene and lie posterior & superior to subclavian Artery.