Repost: The Foot

I've had some thoughts about the feet, as a result of a recent workshop, so I thought I would repost this piece from last year about the anatomy of the foot in preparation for a couple of posts to come.

Firm Foundations


The foot is an extremely complex structure of bones, joints, muscles and connective tissue. Imbalances in its functioning can have an impact all the way up the frame, affecting posture, bearing and well-being in everyday life as well as in your yoga practice. Examining the basic elements of that structure will give us some insight into how the foot supports us in stillness and in movement.

The Bones of the Foot


From above


Bones of Foot (top)

Inner foot


Bones of Foot (inside)

Outer foot


Foot Bones (outside) captioned

Distribution of Weight


The bones of the foot have evolved to support the weight of the body in much the same way that the arch of a bridge supports the entire structure. (1)

Forces acting on the foot


bone support in foot

Forces acting on a bridge keystone


Keystone Action in Bridge

Three Arches


Foot-Arches-(top)-caption

There are three different arch shapes in the foot that contribute to supporting and balancing the weight of the body. The medial arch is the one we generally think of, as in a high or a low arch. There is also a lateral arch, which is much smaller, and a transverse arch across the foot.


Two parts of the foot


Split-Foot-caption

The inner foot, ending in the first three toes, makes up the structure of the medial arch. This bears the most weight. The outer foot bears the least weight and acts as balance. (2)

The tripod of the foot


Foot-weight-points-(top)-ca

Supporting the Arches



The bony arch structures are supported by thick layers of connective tissue and muscle that descend from the lower leg and wrap around the ankle bones.

Medial arch


Med-Arch-Muscles-caption
The supporting muscles are:

Abductor hallucis: Supports the talus and calcaneus. Creates the strung bow action of the arch;
Tibialis posterior: ligament supports talus and navicular;
Flexor hallucis longus: supports talus and calcaneus;
Peroneus longus (not shown): wraps under foot from outer leg and attaches to head of 1st metatarsal (big toe mound), assisting strung bow action of arch.


Ligamentous support of the arches


plantarfascia-captions

The metatarsal heads and calcaneus are drawn together by the support of ligaments and the tone of muscles to create added lift in the bones of the foot, rebounding the downward pull of gravity up through the ankles and legs.

Arch-Spring-Action

Lateral arch


Lat-arch-muscles-caption
The supporting muscles are:

Peroneus longus: Supports calcaneus and cuboid;
Peroneus brevis: assists strung bow action of arch;
Abductor digiti minimi: assists strung bow action of arch.


Transverse arch


The supporting muscles are:

Adductor hallucis: the transverse head attaches to the metatarsal/phalangeal joints crosswise, drawing them in and creating lift;
Peroneus longus: ligament crosses from lateral to medial side of foot, attaching underneath to the head of the first metatarsal and drawing the two sides together to create lift;
Tibialis posterior: attaches to undersides of navicular, cuboid, lateral cuneiform and metatarsals 2-4, creating lift from below.



Notes



1. Mabel E. Todd, 1937. "The Thinking Body: A Study of the Balancing Forces of Dynamic Man." Princeton: Princeton Book Company.

2. Ida P. Rolf, 1977. "Rolfing: The Integration of Human Structures." New York: Harper and Row.