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
If there is a superficial cut in the region of middle pa of posterior triangle of neck, patient will experience problem 
Select and explain. 
A. Adduction of arm, B. Pronating scapula, C. Shrugging of shoulder, D. Abduction of arm
C: Shrugging of shoulder
Answer: C: Shrugging of shoulder 
Explanation: Roof of posterior triangle is formed by the investing layer of deep cervical fascia.Accessory nerve lies just deep to the investing layer at the middle of the posterior border of sternocleidomastoid muscle and across the posterior triangle and reaches the anterior border of trapezius, which it supplies.Shrugging of shoulder is an action of trapezius.