Giving evidence carries risk. A general medical practitioner may find s/he is asked whether the injury was to the ulna or the radius. If this causes the witness difficulty it is a demonstration of Murphy’s law. The ulna and the radius are bones in the arm. If your arm is broken you will in all likelihood be treated in a hospital. A hospital setting facilitates continued familiarity with the bony structure of the arm. In general medical practice detailed knowledge of human anatomy may recede with graduation and the conclusion of training. (It should not but it might, understandably.) So, patient X has a broken arm; it was treated in a hospital and the patient attends the general practitioner for prescription purposes. The doctor’s record of attendances and complaints are relevant.
If the doctor attends to give evidence (an unlikely event in Ireland in current times) s/he will consult with the lawyer of patient X before giving evidence. The discussion is about attendances and complaints. Nobody mentions the name of the bone that was broken. Its name is not relevant. Nevertheless, that very same lawyer is the person most likely to ask the question of the doctor; was it the ulna or the radius? The lawyer assumes the doctor knows and remembers everything related to the practice of medicine. This is obviously unreasonable but is a necessary assumption to, say, carry the lawyer through a series of questions that have not been properly considered by the lawyer.
The consequence is the (minor) embarrassment of the doctor, sitting exposed in the witness box, and revealed as not being able to distinguish the ulna from the radius.
What lawyer knows everything related to the practice of law? None.