Criminal physical abuse includes infliction of unjustifiable pain, injury or mental suffering on the victim by any other person - whether that person is a caretaker, a relative or a complete stranger. Examples would include:
Use of any weapons or objects
Threats of harm
Gross Negligence and Endangerment
Physical abuse also includes endangerment and gross neglect - failure to act by a person who has a legal duty to do so (such as a caretaker - whether paid or not).
Criminal or gross negligence is more than ordinary negligence (handled in civil court). Gross negligence is aggravated, reckless or flagrant and such a departure from what would be the conduct of an ordinarily prudent, careful person under the same circumstances as to be contrary to a proper regard for human life or to constitute indifference to the consequences of those acts.
An example of criminal neglect would be severe bedsores, malnourishment and dehydration caused by a caregiver ignoring medical advice.
An example of criminal endangerment would be pushing a wheel-chair bound victim into on-coming traffic - even if she doesn't actually get hurt.