S Corp Owner Salary Deferrals -where to show them on 1040?

Do salary deferrals (Traditional 401k Contribution) by s corp owners go anywhere on the 1040? I know they go on the W2 Box 12, but looking at the 1040 I don't see a place to show it. In one way I suppose that would be correct since no tax is owed because that money is never paid to the employee/owner because it's taken out of salary, but doesn't that make wages look incorrectly low on the 1040? Is the 1040 what the IRS looks at to determine if a reasonable salary was paid? S Corp owners are supposed to give themselves a reasonable salary and if they contribute the max (or any significant amount) to their 401k it looks like they received much less in salary with no where to show on the personal tax return that money was taken out of salary for this purpose. Am I missing where this is shown?