Explanation:The posterior portal in shoulder arthroscopy is generally considered safe but still requires anatomical awareness. The musculocutaneous nerve courses anteriorly through the coracobrachialis and is vulnerable during anterior portal placement but can be indirectly at risk with deep instrumentation. Careless portal creation may injure surrounding neurovascular structures. The axillary nerve is more commonly endangered during inferior capsular work. Knowledge of portal anatomy and triangulation technique is essential for safe arthroscopic surgery. Proper needle localization minimizes neurovascular risk. Reference: Lo IKY. "Portal Placement and Neurovascular Safety in Shoulder Arthroscopy." Arthroscopy: The Journal of Arthroscopic and Related Surgery, 2004.