It looks like you are using adblocking software. I understand that ads are annoying, but this is one way for me to make a living on this site. As an alternative you might consider becoming a donating member. All ads are removed automatically for donating members.
The 'senda' is a gravel path running alongside the paved road. From Sahagun to Mansilla de las Mulas is a tedious two days walk with some communities along the route. Don't try counting the little trees.