Can not get my in-line mic to work

[ind2403]

Hello I have a Poloroid headphones with in-line MIC and there is only one jack attached to the cable, when I plug it into the PC i can only get the headphones to work and not the mic, why is this as the headphones only supplied the one jack point.

 

[jay32267]

http://www.tomshardware.com/answers/id-1653091/headphone-built-microphone-working.html