Nerve fiber = multicellular, containing both an axon and surrounding myelin sheath. The axon comes from a single neuron, but the myelin sheath is made by a train of many myelinating Schwann cells. In the case of unmyelinated axons, the unmyelinated fiber shares each Schwann cell with several other unmyelinated axons.
Flat feet (pes planus) occur when a child has no arch in their foot. Because an arch does not form, the foot appears to turn to the outside. Children with out-toeing due to flatfeet will rarely experience pain symptoms will not require treatment.
Leg bones usually continue to grow straighter until the child is 6 to 8 years old. Internal tibial torsion is present if the lower leg remains turned in. When the child begins walking, the feet turn inward because the tibia in the lower leg, just above the foot, points the foot inward. As the tibia becomes longer, it usually untwists. The most common overall cause of in-toeing is internal tibial torsion.