Limited mobility in MP thumb joint

[BBEng]

Hi all, this is my fist post on the site, I hope I can get an explanation to my problem.
Since I can remember, I have had very limited ability to bend my MP thumb joint. I cannot touch my palm with my thumb, and when I try to touch my pinky, it's a fair amount of effort. I can barely see a bend in this joint. My brother can touch the bottom part of his palm, but I can't even touch the base of my pinky where it meets with my palm. I'm convinced it's because something is blocking my MP joint and I'm getting barely any flexion. I'm not in any pain, but I'd just like to be able to get more mobility out of my thumb. I can't even make a proper fist because my thumb won't flex.
I've pasted some google image links to show you what I cannot do.

http://www.eorthopod.com/images/ContentImages/Fractures/adult_fractures/adult_hand_fx/adult_finger_fx_thumb_flex_opp.jpg

http://ouhsc.edu/bserdac/dthompso/web/namics/gifiles/thumbflx.jpg

When I push my thumb down to force it in position, it's like there's a bone blocking the movement. What can I do to get some mobility. And is there a name for this condition? Thanks.