body shifts from the heel, to the ball of the foot, and then to the toes, the plantar fascia creates the tension that allows the foot to bend and move through the transfer of weight and the force required to push off the toes into the next step. This mechanical function will be discussed in more detail below. There is also a relationship that exists between the plantar fascia, the Achilles tendon, and the gastrocnemius muscle of the lower leg. This will also be explored in the treatment section of this course. With such a heavy burden being placed on such a relatively small structure in the foot, it is easy to see why the plantar fascia is a common site for dysfunction, inflammation, and pain.
Exercise 1 With bare feet, sit in a chair with your knees bent at a 90-degree angle with both feet on the floor. Cross the left leg over the right, resting the left outer ankle on the thigh of the right leg. You should be able to see the arch of the left foot and easily reach the sole of the foot. With your right thumb tip, press into the sole of the foot at the front and center of the heel, right in front of the mound of the heel. Dorsiflex the toes; with your left hand, trace the plantar fascia from where the right thumb is pressing in forward towards the ball of the foot. You should be able to easily feel the thickest part of the plantar fascia, or the plantar aponeurosis, with the toes flexed. You may even be able to see the tension created by the plantar aponeurosis on the underside of the foot when the toes are flexed. Repeat the exercise, moving the pressing thumb slightly to either side and tracing forward with the other hand again. This should give you a clear indication of the location and superficial nature of your plantar fascia.
Note : Image Credit: The Journal of the American Osteopathic Association
What does the plantar fascia do? The plantar fascia has many roles in the normal function of the foot, the most important being its integral part of the Windlass Mechanism. In 1954, John Hicks first coined the term Windlass Mechanism , which is derived from sailing terminology, to describe the role of the plantar fascia in the movement of the foot. “Hicks originally described the foot and its ligaments as an arch-like triangular structure or truss. The calcaneus, midtarsal joint, and metatarsals (the medial longitudinal arch) formed the truss's arch. The plantar fascia formed the tie-rod that ran from the calcaneus to the phalanges. Vertical forces from body weight travel downward via the tibia and tend to flatten the medial longitudinal arch. Furthermore, ground reaction forces travel upward on the calcaneus and the metatarsal heads, which can further attenuate the flattening effect because these forces fall both posterior and anterior to the tibia” (Physiopedia, 2018). In simpler terms, the “Windlass Mechanism” refers to what happens in the foot when it comes between the downward force of the weight of the body and the upward force of that weight hitting the ground. The Windlass Mechanism is what allows you to land on the heel, then carry through to push off with the ball of the foot and the big toe as part of a normal stride. The primary function of the plantar fascia is to create tension that shortens the distance between the heel and big toe, acting as a pulley on the underside of the foot, and allowing the small bones of the foot to articulate with one another as the shape of the foot changes with motion. The Windlass Mechanism helps
to create the propulsion of your stride as you lift the heel and push off with the big toe. This action happens naturally when barefoot, as the foot has the ability to move without restrictions. It can be somewhat compromised when wearing shoes: The stiffness of shoes can limit the normal range of motion of the structures of the foot.
Note . Image Credit: Physiopedia
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Book Code: MTX1324B
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