Skeletonize petioles images

Hi,
I extracted petioles by mathematic morphology and want now to skeletonize at 1 pixel wide for measure it.
There are some petiole image examples : Index of /temp/petioles
Please help me !
Best regards

I precise that the petioles may be curved, double-curved, triple-curved, etc horizontal, vertical or oblique

noone has an answer ?