portio por·ti·o (pôr'shē-ō', -tē-ō')
n. pl. por·ti·o·nes (-shē-ō'nēz, -tē-)
A part or segment, as of an organ.
This nerve is the portio major or superficialis of the nerve usually known as the ramus ophthalmicus superficialis in the adult.
Deal with the ear, and remember that it has its portio mollis as you gently probe your way into its tube.