Injury to long thoracic nerve. It can be tested by asking the patient
Long thoracic nerve supplies the serratus anterior muscle, which helps in overhead abduction of shoulder, pushing and punching movements. So it can be tested by asking the patient for forward pressure with the hands against a wall, or against resistance offered by the examiner. B D Chaurasia 7th edition Page no : 46,47
Resistance against wall
Raise the arm above head
Touch opposite shoulder
Lift a heavy object.
Upper limb