The plantar fascia is a ligament-like band running from your heel to the ball of your foot. This band pulls on the heel bone, raising the arch of your foot as it pushes off the ground. But if your foot moves incorrectly, the plantar fascia may become strained. The fascia may swell and its tiny fibers may begin to fray, causing plantar fasciitis. CausesPlantar fasciitis is often caused by poor foot mechanics. If your foot flattens too much, the fascia may overstretch and swell. If your foot flattens too little, the fascia may ache from being pulled too tight. Foot flattens too much Foot flattens too little SymptomsWith plantar fasciitis, the bottom of your foot may hurt when you stand, especially first thing in the morning. Pain usually occurs on the inside of the foot, near the spot where your heel and arch meet. Pain may lessen after a few steps, but it comes back after rest or with prolonged movement. Related ProblemsA heel spur is extra bone that may grow near the spot