Final answer:
For a suspected musculoskeletal shoulder injury, the best initial management is to place the arm in a sling and secure it with a triangular bandage, later followed by physical therapy.
Step-by-step explanation:
The suspected musculoskeletal injury of the shoulder is best managed by placing the arm in a sling and using a triangular bandage to secure it to the body. This technique provides support while also allowing for some movement, which can help maintain the range of motion during recovery. The management strategy may eventually include an appropriate physical therapy plan once initial healing has occurred, to restore full range of movement and function to the injured shoulder.