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By Mayo Clinic staffYour feet are highly specialized structures. Each foot is made up of 26 bones held together by 33 joints and more than 100 muscles, tendons and ligaments. The intricate alignment of these structures results in the formation of your arches.
As you walk, these springy, elastic arches help distribute your body weight across your feet and legs. Your arches also play an integral role in how you walk. They act as rigid levers for proper mobility, but they must also be resilient and flexible to adapt to various surfaces.
Not all feet are the same
Flat feet are normal in infants and toddlers, because the foot's arch hasn't yet developed. Most people's arches develop throughout childhood, but some people never develop arches. This is a normal variation in foot type, and people without arches may or may not have problems.
Arches can also fall over time. Years of wear and tear can weaken the posterior tibial tendon, which runs along the inside of your ankle, from above your ankle to your arch. The posterior tibial tendon is the main support structure for the arch. An overload to this tendon can cause inflammation of the tendon (tendinitis) and even tearing of the tendon. Once the tendon is damaged the foot's arch loses support and can flatten.