Final answer:
A dislocated shoulder injury that results in weakened ability to abduct the shoulder most likely affects the 1) axillary nerve, which innervates the deltoid and teres minor muscles important for shoulder abduction.
Step-by-step explanation:
A dislocated shoulder can lead to various complications, including potential nerve damage. The nerve that would most likely be affected during a shoulder dislocation, particularly when one experiences weakened ability to abduct the shoulder, is the axillary nerve. The axillary nerve innervates the deltoid and teres minor muscles, which are crucial for the abduction of the shoulder joint.
Therefore, if the axillary nerve is stretched or damaged, a person may have difficulty lifting their arm away from the side of their body, a motion known as abduction. This can be a significant limitation, as the abduction is necessary for many daily activities and various sports. The other nerves listed, such as the musculocutaneous, radial, and ulnar nerves, serve other functions and muscles of the arm and are less likely to be directly implicated in a dislocated shoulder affecting abduction. The answer is option 1.