As outlined in our basic foot anatomy post, the main functions of your feet include absorbing shock, adjusting to changes in uneven ground and propelling your body forward. Your foot’s arches play an integral role in making this happen. Several components work together to ensure your feet maintain their arches. They are:
- The shape of the bones and how they relate to each other
- Your plantar fascia and ligaments
- The muscles in your feet
While no one argues that arches exist in your feet, there is a bit of controversy when it comes what those arches are. The traditional viewpoint says the foot has three main arches, but opposing views say otherwise.
Traditional Viewpoint: Three Main Arches
When you stand on your feet, you’re actually standing on a tripod dome that distributes the weight to the tripod’s three points. One point is at the base of your heel bone, or calcaneus, and the other two are at the heads of your first and fifth metatarsals, or at the base of your big toe and your fifth toe. In the three-arch theory, two arches run lengthwise down the bottom of your foot and a third runs side-to-side.1
Medial Longitudinal Arch: This arch runs from your calcaneus up through your talus, navicular, three cuneiform bones, incorporating your first three metatarsals and making up the medial border of your foot. At the top of this arch sits the talus, the topmost portion of the arch known as the keystone.
The keystone takes on your body weight and, although it may depress while bearing weight, it generally never completely flattens or touches the ground. This arch is incredibly flexible and brings a spring to the foot.
Lateral Longitudinal Arch: This arch extends from your calcaneus up through the cuboid and fourth and fifth metatarsals. It not only touches the ground regularly, but it typically rests there when bearing weight. The cuboid serves as the functional keystone in this arch, which is much more stable and less flexible than the medial longitudinal arch.
Scientist John Basmajian believed this arch was the one true arch of the foot, as it had the components necessary to constitute an arch: a keystone at the top of an ascending and descending flank. The ascending flank is the calcaneus, the cuboid is the keystone and the fourth and fifth metatarsals serve as the descending flank.2
Transverse Arch: This arch runs side-to-side, extending through your foot’s three cuneiform bones to the cuboid bone. The second cuneiform bone is the keystone of this arch.
Other Arch Viewpoints
Other viewpoints say the arches are more numerous and complex than initially believed.
Fundamental Arch: Some argue the two aforementioned longitudinal arches contribute to a longitudinal arch known as the fundamental arch. The most stable arch in your foot, it’s referred to as fundamental because it would remain intact even if all the other foot bones that are not part of the arch were removed. The fundamental arch runs from your calcaneus through your cuboid, third cuneiform and third metatarsal bones. The cuboid is its keystone. 3,4
Series of Transverse Arches: Instead of a single transverse arch, some say each foot has a series of transverse arches. This view notes the arch that runs along the distal end of your metatarsals only exists when your foot is not supporting weight. Several relatively complete arches are made up of the front part of your tarsal bones and back part of your metatarsals. Behind these arches sits yet another partial arch in the middle of your tarsus that only forms a full dome when the inside borders of your two feet are placed together.3
No Transverse Arch: The tripod theory has been embraced vehemently enough for some to often ignore another controversial viewpoint: that the transverse arch that runs at the distal ends of your metatarsals does not exist. If this were true, the tripod theory would fall flat, literally, as there would be no arch with endpoints neatly situated at the first and fifth metatarsals to form the uppermost side of the triangle running across your forefoot.5
Regardless of which viewpoint you choose, one thing remains clear. Arches are essential components that ensure your feet can properly perform all the complex actions they were designed to do.
REFERENCES:
- Lippert L. Clinical Kinesiology and Anatom 5th ed. Philadelphia, PA: F. A. Davis Company; 2011.
- Macconaill MA, Basmajian Muscles and Movements: A Basis for Human Kinesiology. Revised ed. Malabar, FL: Krieger Pub Co; 1977.
- Sweigard L. Human Movement Potential: Its Ideokinetic Facilitation. New York, NY: Harper & Rowe, Publishers, Inc.; 1974.
- Dowd I. Kinesthetic Anatomy and Biomechanics of Motion: The Limbs. Presented as a lecture series; January 18 to April 19, 2014.
- Michaud TC. Human Locomotion: The Conservative Management of Gait-Related Disorders. Newton, MA: Newton Biomechanics; 2001.