If you will take your left leg up, placing the ankle on your knee and look at the bottom of your foot, there is a number 7 in the sole of your foot, looking back at you! When, long ago, our ancestors descended from the trees, more and more distinctness grew between the structure and roles of the feet and hands. Hands retained and refined the actions of grasping that had been used in climbing. The feet took on more the role of support, thickened and lost some of their articulate grasping action.In primate feet and hands there are a series of little muscles called the “contrahentes”. They insert onto digits I, II, IV and V and pull them down and together. Wikipedia says, “They facilitate convergence of the digits.” I love it – the harmonic convergence of the digits.
In humans there is still an important and vestigial remnant of the contrahentes. That is the “adductor hallucis”. The adductor hallucis has two heads which together form the number “7” in your foot.
One, the transverse head, arises from the plantar metatarso-phalangeal ligaments of toes 3, 4, and 5.
The other head, the oblique head, occupies the hollow space under the 1st, 2nd, 3rd and 4th metatarsals. It arises from the bases of the second, third and fourth metatarsals and the tendon sheath of peroneus longus.
Both heads insert on the lateral side of the base of the first phalanx of the big toe.
Together this clever and important muscle simultaneously pulls the toes down and together, much as you see especially in a baby’s inclination to grasp your finger with its foot.
The adductor hallucis is the only muscle that reminds us explicitly of the grasping role of the foot earlier in evolution.
Even today, through the important function of the transverse arch, we grasp the ground more or less with each step. With the help of the bones’ shape, the ligaments’ tensile integrity, and, to a large extent as well, the adductor hallucis, we carry out our unconscious articulate conversations with the shapes we encounter, especially when barefoot.
And it is to the transverse head of adductor hallucis, as well as the tendon of peroneus longus, that we owe, in part, the origin of the spring in our step.
So when you are working with the foot, don’t forget to deeply explore and massage into the lucky number 7! Adductor hallucis unites you with your early animal ancestors – in a kind of harmonic convergence of species as well as digits, reminding us that we have in some respects not come all that far. And it enables you to have both a more grounded and more buoyant relationship to Mother Earth.
And maybe even a little nostalgia for life in the trees.