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.
Flat Feet. Flat feet are just as they sound - feet that are flatter on the undersurface (or plantar surface) than they should be, because the arches (insteps) have dropped. This can (but does not always) lead to pain and tiredness in the feet. It can also cause problems in the ankles, legs or back.