These sources indicate that it is the big toe (great toe, hallux).
?The big toe, commonly called the great toe, helps to maintain balance
while the little toes function like a springboard. The three inner
metatarsal bones provide rigid support while the two outer metatarsal
bones, one on each side of the foot, move to adapt to uneven
"The function of the toes, especially the big toe, is to help us
balance, and to propel us forward during walking or running."
"It is very important that we have good balance. A lot of our balance
actually comes from the big toe. It is similar to the fourth leg on
the coffee table.
As we stand and we pressure our big toes in a downward motion, it
allows us to balance our legs above the ankle. If we were to take the
big toe away, we would have to re-train the body to use different
muscles and the proprioceptor nerves to balance the body." >>more
Normal toe function
?The toes are important in force and pressure transfer in the late
stance phase of gait (Hughes et al 1990). They take 30-40% of peak
force and 70% of peak pressure. The great toe is most important and
the others have progressively less importance. Loss of this function
may precipitate metatarsalgia.?
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"big toe" balance
"great toe" balance