mrcem2-1101

mrcem2-1101

You assess a patient in a clinic who has been diagnosed with a neuropathy affecting the muscles around her shoulder joint. During the examination, you observe that she has significant restriction in the abduction of her arm. Your consultant examines the patient and instructs her to raise her arms parallel to the ground in the scapular plane. When rotating the arm internally with the thumbs pointing downwards, she is unable to sustain the position with her left arm when pressure is applied.
Which nerve is most likely to have been affected in this scenario?