Fingernails grow from the matrix. The nails are composed largely of keratin, a hardened protein. As new cells grow in the matrix, the older cells are pushed out, compacted and take on the familiar flattened, hardened form of the fingernail.. :3
The health specialist assigns and ICD-9 CM code E000.0 - E999.1 for classification of external causes of injury and poisoning. Since the patient suffered a fractured tibia while on a ski trip, it doesn't mean that he was injured while skiing. The health specialist will need to find the main cause of his fractured tibia, and in that, will be given ICD-9 code E000.0 - E999.1.
Public safety regulations protect workers because they provide regulations about various aspects of public safety that increase the safety of different job-related possible occurences which could influence how workers perform their job (mostly in terms of their own safety).