Will an ultrasound on a shoulder show any nerve damage?

An MRI of the shoulder may get detailed views of soft structures in the shoulder, an ultrasound may be suboptimal in detecting abnormalities to the nerve level, may still pick fluid collections for example. Best would be to start with a clinical exam with an orthopedic surgeon that specializes in shoulder pathology.

Some experience with skilled operators in the USA can provide inferences but not always full answers. An EMG directly examining the plexus is best but needs expert skills to do properly

Ultrasound is best for showing tissue damage. An EMG would be a better way to check for nerve injury