If a person cracked skull bones, he would have had a head scan.
If he did not have a scan, then perhaps only the skin was "cracked" open. If the person is normal, then there is no need to worry (but doesn't mean the head is 100% normal inside, because there is no way in the world to know that). If the person has symptoms, then he needs to see his dr. Symptoms may not be due to old head injuries.