'Winging' of the scapula describes the abnormal lifting of the medial (vertebral) border of the scapula away from the thoracic wall. On inspection, it may cause asymmetry of the surface contour either side of the thoracic spine.
The lesion may not be obvious until the patient contracts serratus anterior against resistance e.g. by pushing against a wall with arms extended.
It may be caused by weakness or paralysis of serratus anterior.