How does the Tenth Amendment limit federal powers?

The Tenth Amendment to the United States Constitution limits the powers of the federal government to those provided for in the Constitution and its amendments, with all others powers being "reserved" to the individual states and "the people."  There was some discussion about whether or not the word "expressly" should be included so that it would read "expressly delegated," but ultimately that word was not used. This is significant because if the federal government has only expressly delegated powers, it is limited to those that are "listed" in the Constitution, what are called the enumerated powers.  Without the use of that limiting modifier, the federal government has been held to have unenumerated powers, mostly Congress, under what is called the "necessary and proper" clause (Article I, Section 8), which allows Congress to make any laws that are necessary and proper to carry out the enumerated duties, those that are named specifically.  The fact that the necessary and proper clause was included has been interpreted to mean that it includes other powers.