The medical expenses would not be directly on the Form 1040. They get totaled with other itemized deductions and are placed on line 40 of Form 1040. The breakdown of itemized deductions, including medical expenses and the calculation related to your AGI, would be found on Schedule A, which would accompany your tax return. I have included a copy of a blank Schedule A below so you can have a visual. Now, if you don't have a Schedule A in your return at all, or you see the standard deduction amount on line 40 for your filing status, then you didn't have enough overall itemized deductions to deduct them.
https://www.irs.gov/pub/irs-pdf/f1040sa.pdf