EVERYBODY NEEDS A PAIR OF RED SHOES.
—JUDITH HANSON LASATER
WE OFTEN IGNORE our feet except when they hurt. We force them into stylish but ill-fitting shoes and walk around on high heels, shifting our weight forward onto the metatarsals, which are not equipped to receive it, and rolling onto the outside of the ankles. We paint our toenails but ignore our flat arches.
On my first trip to India, I was walking in a city garden one day and was struck by the bare wet footprints left by one of the gardeners on the stone pathway. Each footprint looked like the drawing of a perfect foot. Each toe print was round and perfect, the arch was clearly lifted, and the heel print was an even ovoid. After that experience, I began to notice other feet in India and how the wearing of simple sandals had allowed so many people to have wide, strong, and open feet. It was quite a comparison to the Western feet I saw in my yoga class. Those feet had first (big) toes that were often abducted, ankles that were pronated, arches that were fallen. The entire foot was generally misshapen from wearing shoes that confined and restricted.
Luckily, the conscious practice of yoga asana can help us regain healthily shaped feet by stretching and strengthening the muscles of the feet and reminding us to open our toes and stand well. Study this chapter to learn about the structures of the feet and ankles and how to improve your foot function.
BONES OF THE ANKLE
There are fifty-two bones in the feet—about one-fourth of all the bones in the body. The ankle bones, or tarsals, are seven in number. The most superior one is the talus. It is a pivotal bone, connecting the tibia superiorly, the calcaneus distally, and, on the sides, the lateral and medial malleoli. There are no muscles that attach to the talus.
Just distal to the talus is the calcaneus (Figures 10.1 and 10.2). This is the largest bone in the foot and therefore is important in weight bearing. The calcaneus is located at the posterior foot and is at the main junction where the weight of the body is translated to the ground (Figure 10.3).
10.1 TALUS AND CALCANEUS, LATERAL VIEW
10.2 TALUS AND CALCANEUS, MEDIAL VIEW
10.3 TALUS AND CALCANEUS, SUPERIOR VIEW
When practicing Tadasana, it is important to understand the weight-bearing function of the calcaneus. Sometimes yoga students are instructed to equalize the weight throughout the foot. But this instruction does not take into account the actual structure of the ankle and foot.
Take a minute to notice your leg, ankle, and foot in standing. The leg joins the ankle at the back of the foot, not at the center in the arch. The large talus and calcaneus are at the back of the foot as well. This is the site of weight transfer, not the middle of the foot. The bones of the posterior foot are the major weight-bearing bones. The smaller bones of the ankle and the long slender bones of the foot (metatarsals) are used mainly for balance and propulsion, though the metatarsal heads do bear some weight. However, if we follow the dictates of structural formation, our weight in standing is meant to be borne mostly at the back of the foot, on the whole heel, which is formed by the calcaneus.
The other function of the calcaneus is to act as a strong lever as the body moves into plantar flexion. This bone is the site of attachment of the Achilles tendon, the largest and strongest tendon in the body. With the strength of the gastroc-soleus muscle focused here, we have tremendous propulsive force for walking and running through the action of the calcaneus. Moving distally, between the talus, the calcaneus, and the metatarsals, in the next layer are the five tarsal bones, which correspond to the instep of the foot (Figures 10.4 and 10.5). The navicular is located on the medial side of the foot, between the talus and the cuneiform bones. The navicular articulates with the first, second, and third cuneiforms. The cuboid bone, so named because of its shape, is located on the lateral side of the foot. It articulates with the calcaneus proximally, with the lateral cuneiform and the navicular medially, and with the fourth and fifth metatarsals distally (Figure 10.6).
10.4 TARSALS, MEDIAL VIEW
To find your navicular bone, sit on a chair and cross your right foot over your left leg easily at the knee, so you can see the arch side of your foot. Press your fingers firmly from the medial base of your first toe along the side of the first metatarsal, and then slowly move them proximally toward the ankle. The first prominence you find will be slightly medial; it is the first cuneiform. If you continue to move a short distance in this direction, you will find another prominence about an inch or an inch and a half away; this is the navicular bone.
You can easily locate your cuboid bone as well. Once again sit on a chair and cross your right foot over your left leg easily at the knee. Now run your left fingers firmly along the lateral border of your foot, from your little toe toward your ankle, this time with your left hand. At the proximal end of your fifth metatarsal bone, which forms this border, you will feel a protuberance. You will feel a bit of a “drop off” here at the proximal end of the fifth metatarsal. Move your fingers just proximal to this drop off, and you will find the cuboid bone.
The remaining three tarsal bones are the cuneiform (“wedge-shaped”) bones, which create a transverse arch of the foot. The medial cuneiform is the largest and articulates with the navicular, the second cuneiform, and the first and second metatarsals. The intermediate cuneiform is the smallest of the three; it articulates with the navicular, the other two cuneiforms, and the second metatarsal. The last cuneiform is located most laterally of the three cuneiforms, and it articulates with six bones: the navicular, the intermediate cuneiform, the cuboid, and the second, third, and fourth metatarsals. You can palpate the cuneiforms across the top of your medial arch.
10.5 TARSALS, LATERAL VIEW
10.6 METATARSALS AND PHALANGES, SUPERIOR VIEW
BONES OF THE FOOT
There are five metatarsals, numbered from one on the medial side to five on the lateral side. The bodies of the metatarsals are long and slender and slightly curved upward toward the top of the foot; they consist of a proximal base, a body, and a distal head. The first metatarsal is remarkable because it is much thicker and bigger that the other four.
There are fourteen phalanges on each foot. The first toe only has two, a proximal and distal one, while all the other toes have three each. These phalanges as a group consist of three rows: proximal, medial, and distal, according to their location.
JOINTS
The ankle joint is surrounded by a fibrous capsule. It is a hinge joint, consisting of the medial malleolus of the tibia and the lateral malleolus of the fibula, which fits around the talus. The ankle joint dorsiflexes and plantar flexes; it has a large range of movement. In plantar flexion, however the joint is less stable. The movements of the ankle to the foot are supported by a number of ligaments and muscles.
Each foot has thirty-three joints upon which we balance. They are formed into two distinctive longitudinal arches as well as into a series of transverse arches. The first arch is the medial longitudinal arch, the largest and most easily recognizable one, usually called “the arch of the foot” in asana class. It is formed by the juncture of the calcaneous, the talus, the navicular, the three cuneiforms, and the first three metatarsals. The support of the long arch of the foot is created specifically by the calcaneo-navicular ligament, the long plantar ligament, and the tibialis posterior muscle. The second arch is the lateral longitudinal arch. It is much smaller and extends from the calcaneous to the fifth metatarsal. It can be seen on the outside of the foot.
There are also a series of transverse arches that run from the posterior metatarsal heads to the anterior part of the tarsal bones. In fact, if you put your feet together at the medial longitudinal arch, as is sometimes taught in Tadasana, the transverse arch of the two feet creates a dome. When the body is raised up on one ball of the foot, as in dancing or when wearing high heels, the stress on the arch of the foot is increased many times.
CONNECTIVE TISSUE
Six major ligaments hold the ankle in place. Four are on the lateral side and attach to the fibula, and thus all have “fibula” in their names.
The lateral collateral ligament of the ankle is actually made up of three components—the anterior and posterior talofibular ligaments (ATFL and PTFL) and the calcaneofibular ligament (Figure 10.7). The lateral collateral ligament is the site of 85 percent of ankle sprains. This is true in part because the lateral tibia does not extend as far as the medial, thus allowing more instability at the lateral side of the ankle.
10.7 LATERAL COLLATERAL LIGAMENTS OF THE ANKLE
10.8 DEEP AND SUPERFICIAL LAYERS OF THE MEDIAL COLLATERAL LIGAMENTS OF THE ANKLE
The medial collateral ligament of the ankle is also called the tibial collateral ligament, or the deltoid ligament (Figure 10.8). The major function of the deltoid ligament is to prevent too much lateral movement of the talus. It also has an important part to play in plantar flexion.
Remember that the ankle joint is less stable in plantar flexion. This is true because in plantar flexion the narrower part of the talus is held snugly between the medial and lateral malleoli and the arch is stressed. Thus the anterior talofibular ligament is more often the site of injury because it is taut and stressed in plantar flexion. In addition, the inferior talus and the superior calcaneus are held together by the interosseous talocalcaneal ligament as well as the anterior and posterior ligaments between these two bones.
These are the main ligaments of the ankle joint. The other ligaments reinforce the functions already mentioned and can be seen in Figures 10.7 and 10.8. Each foot has over a hundred ligaments, and a detailed explanation of each is beyond the scope of this book. They all function to maintain the stability and integrity of the foot and its arches.
The tarsal and metatarsal joints form gliding joints with many plantar and dorsal ligaments for integrity. Here are the important ones:
▶ The long plantar ligament runs from the cuboid ridge to the calcaneous and then attaches to the base of metatarsals two through five; it provides medial arch support.
▶ The short plantar calcaneus cuboid ligament is inferior to the long plantar ligament that runs from the calcaneus to the cuboid.
▶ The plantar calcanonavicular ligament runs from the calcaneus to the navicular bone to support the head of the talus.
The metatarsophalangeal and interphalangeal joints of the foot are supported by paired collateral ligaments and a deltoid and glenoid ligament as well.
NERVES
The three compartments of the leg are innervated by three different nerves. The anterior compartment muscles are controlled by the tibial nerve, the posterior crural muscles by the deep fibular nerve, and the lateral crural muscles by the superficial fibular nerve (Figures 10.9 and 10.10).
10.9 DEEP NERVES OF THE LEG, ANTERIOR VIEW
10.10 NERVES OF LEG, POSTERIOR VIEW
To observe the route of the nerves around the ankle and foot, please review the Nerves section of chapter 9 and the accompanying diagrams.
It is not uncommon for yoga students and others to feel nerve pain in the plantar surface of the foot (Figure 10.11). One of the most common causes is a neuroma, a thickening of the nerve sheath on the bottom of the foot, which can press on the nerve and cause pain.
Neuromas of the foot are the most common between the metatarsals. One of the reasons neuromas form is from the stress created by poor bio-mechanics in the foot. When weight is not distributed well through the arch and metatarsals, an irritation to the nerve sheaths may result on the bottom of the foot, causing a neuroma to develop. A frequent solution is surgical excision to remove the neuroma. Unfortunately, however, surgery can create scar tissue in the area and thus exacerbate the condition it was attempting to cure. Learning the correct alignment of the feet in Tadasana and standing poses, as well as practicing strong stretching movements for the plantar surface of the foot, can help prevent this condition and ameliorate it once it has occurred.
MUSCLES
The leg from the knee to the foot is known as the crus, and it is divided into three crural compartments: anterior, posterior, and lateral (Figure 10.12). A complex group of muscles work together in the lower leg to act upon the knee joint, the ankle joint, and the foot. (These do not include the intrinsic muscles of the foot, which are discussed below.)
The anterior compartment contains muscles that dorsiflex the ankle. The posterior compartment contains the plantar flexors of the ankle, the flexors of the toes, and the muscles that invert the foot. The muscles of the lateral compartment evert the ankle.
▶ Anterior crural muscles work as a group to dorsiflex the foot, especially during the swing phase of walking. This is the portion of walking when the back leg is swinging through from the back to the front to become the new stance leg. If the anterior compartment did not dorsiflex the foot at this time, the back foot would hit the floor as it moved forward (Figure 10.13).
▶ Posterior crural muscles, some of the most powerful in the body, are divided into two layers: superficial and deep. Part of the superficial muscles act upon the knee as well as the foot. The gastrocnemius, plantaris, and popliteus, presented in chapter 9, are discussed again here, with the addition of the soleus. These muscles are sometimes called secondary knee flexors (Figures 10.14, 10.15, and 10.16).
10.11 (RIGHT) NERVES OF THE PLANTAR SURFACE
10.12 (FAR RIGHT)ANTERIOR TIBIALIS AND ITS EFFECT ON THE FOOT; ANTERIOR CRURAL MUSCLES
10.13 ANTERIOR CRURAL MUSCLES
▶ Lateral crural muscles are on the outside of the lower leg. These muscles need to be stretched to practice Padmasana (Figure 10.17).
INTERACTION OF THE ANTERIOR AND LATERAL COMPARTMENT MUSCLES
The anterior tibialis and the peroneus longus and brevis are shaped like a sling under the foot. All these muscles insert on the first metatarsal, and the first two also insert on the first and third cuneiform, respectively. The net effect of this structure is that the anterior tibialis and the peroneals tend to add stability to lateral and medial movements at the ankle. This structure also helps to support the arch. The peroneus longus supports the lateral arch and helps with balance when one is standing on tiptoes (Figure 10.18).
MUSCLES OF THE FOOT
Each foot has nineteen intrinsic muscles. These are muscles that start and stop on the foot itself and do not cross the ankle joint. There is one intrinsic muscle on the dorsal surface of the foot, the extensor digitorum brevis. It arises from the distal and lateral calcaneus and travels across the foot. It has four tendons of insertion; the largest ends at the proximal phalanx of the first toe (sometimes called the extensor hallucis brevis) and the other three tendons insert on the second, third, and fourth toes, on the tendon of the extensor digitorum longus muscle. The action of the extensor digitorum brevis is to weakly extend the proximal phalanges of the first four toes. The tendons of this muscle can often be plainly seen on the top of the foot when the toes are dorsiflexed.
To better understand the muscles on the plantar surface of the foot, note that these muscles are arranged into four distinct layers. The bottom of the foot is covered by a thick fascial layer, the plantar fascia, which can sometimes become irritated and create a common condition known as plantar fasciitis.
10.14 (RIGHT) GASTROCNEMIUS PULLED BACK TO SHOW THE SOLEUS AND POSTERIOR COMPONENT
10.18 (FAR RIGHT) PERONEALS AND EFFECT ON THE FOOT AND LATERAL COMPONENT
10.15 POSTERIOR CRURAL MUSCLES, SUPERFICIAL LAYER
10.16 POSTERIOR CRURAL MUSCLES, DEEP GROUP
10.17 LATERAL CRURAL MUSCLES
The four layers work together to flex the toes. The medial plantar muscles control the first toe, the lateral plantar muscles control the little toe, and the intermediate muscles control the medial three toes (Figures 10.19, 10.20, 10.21, 10.22, and 10.23).
KINESIOLOGY
Four movements are allowed at the ankle joint. Plantar flexion, or pointing of the foot, requires some passive joint movement of the talus. In order to plantar flex, the talus must move anteriorly. Because there are no muscles attached to the talus, this movement must be allowed by the laxity in the connective tissue attached to the talus. In a normal ankle joint, there is approximately 45 degrees of plantar flexion.
10.19 FOUR LAYERS OF THE BOTTOM OF THE FOOT
10.20 PLANTAR MUSCLES, FIRST LAYER
Dorsiflexion is limited to approximately 20 degrees. To have a full range of dorsiflexion, the talus must glide posteriorly. Dorsiflexion is also limited by tightness in the gastrocnemius and soleus muscles and the Achilles tendon. Many students present with tightness in this area of the body, in part because in our culture we do not often squat. Tightness in this area can also be created by running and other athletic pursuits and by the frequent wearing of high heels. If the knee is bent, the gastrocnemius is stretched, and some increase in dorsiflexion is possible.
A simple stretching exercise can be used to stretch this area, as well as to isolate the stretch of the gastrocnemius and soleus, in order to improve dorsiflexion. Stand facing the wall, with your hands on the wall at shoulder height. Then place your right foot back about two feet, with your heel turned slightly out. Your front knee should bend directly over the front foot. The stretch is created by making sure your back heel is held firmly on the ground throughout. Hold the stretch for at least 30 seconds. This variation will stretch the gastrocnemius. Remember that the gastrocnemius is a two-joint muscle, and, in order to stretch it, the muscle must be stretched over both the knee joint and the ankle joint.
FIGURE 10.21 PLANTAR MUSCLES, SECOND LAYER
FIGURE 10.22 PLANTAR MUSCLES, THIRD LAYER
FIGURE 10.23 PLANTAR MUSCLES, FOURTH LAYER
10.24 PRONATION AND ITS EFFECT ON THE POSITION OF THE KNEE
To stretch the soleus, a one-joint muscle, assume the same position facing the wall. This time, however, bend your back knee as well as your front knee. Be very careful to keep your back heel on the floor when you bend this knee, however. Bending the back knee will release the stretch of the gastrocnemius over the knee joint, thus emphasizing the stretch of the soleus muscle over the ankle. The first stretch of the gastrocnemius will be felt throughout the calf area. The second stretch of the soleus will be felt from the mid-calf area down, the location of the soleus.
The third movement allowed at the ankle joint is supination, which is done by gliding at the subtalar joint, as well as by gliding at the joints between the talus and the calcaneus and navicular bones. This movement is quite free and can be overdone in poses like Padmasana if you go into the pose by pulling on your foot instead of keeping the ankle in neutral and placing the ankle on the opposite thigh. The ability to supinate easily can lead to a sprain of the lateral collateral ligaments of the ankle. Inversion of the foot often accompanies supination of the ankle.
The fourth movement of the ankle is pronation (Figure 10.24). Pronation is allowed by gliding at the subtalar joint, as well as by gliding at the joints between the talus, calcaneus, and navicular bones. Pronation is much less free than supination. Pronation of the ankle can be increased by ligamentous laxity in the foot, creating pronation of the longitudinal arch and thus of the ankle. Pronation of the ankle can directly effect the healthy functioning of the knee joint by causing increased tibial torsion, an increased internal rotation of the tibia on the femur. Eversion of the foot often accompanies pronation of the ankle.
ANKLE SPRAINS
Caution: If you suspect an ankle sprain, send the student immediately for medical attention, including to a therapist who works with connective tissue. A sprained ankle is one of the most under-treated injuries on a long-term basis and can lead to problems with the knee joint.
Ankle sprains are actually tears in the ligamentous support to the joint. They can be partial or, occasionally, complete. Sprains usually occur when the individual steps off an uneven surface or falls during athletic endeavors and lands on the ankle in supination. Pain can be severe, and swelling is usually immediate, although the amount of pain may not be correlated to the degree of injury.
One way to know if your student has a mild ankle sprain is to ask her to perform the following. Have her sit in a chair and lift the affected side off the floor. Now have her move her ankle passively with her hand to see if that elicits pain. Pain on active movement could be caused by a sore or injured muscle and not a sprain. She or another trained person can now move her foot gently so it plantar flexes and supinates at the same time. If this creates pain, it is likely that there is an injury to the ATFL, and she should seek medical attention.
EXPERIENTIAL ANATOMY
For Practicing
10.25 UTTHITA TRIKONASANA
Applied Practice 1: Foot Position in Standing Poses
Prop: 1 nonskid mat
Take Care: When you turn the front foot out, also drop the femur toward the back of your thigh. Make sure that this movement does not create pain in the inner knee structures.
ONE OF THE MOST important focus points in standing poses is the position of the feet. In Utthita Trikonasana, for example, the front thigh is rotated externally about 90 degrees, so the foot is facing out to the side and the back foot is rotated medially and facing inward about 45 degrees (Figure 10.25). On the one hand, many students find it easy to supinate the front foot and pronate the back foot. On the other hand, students who are limited in internal rotation because of tight hip external rotators sometimes pronate the front foot. This tightness in the back hip can result in a supinated back foot, as the student tries in vain to externally rotate the tight back hip and ends up instead supinating the ankle and foot.
During your practice of Utthita Trikonasana, observe your front foot after you have turned it out from the hip. Place weight both on the ball of the first toe at the proximal end of the first phalanx and equally on the lateral border of the calcaneus.
Now observe your back foot. If you feel steady, close your eyes and feel where the weight is on the foot. You may need to press a little more weight on the outside of your back foot to keep the relationship of even pressure on the first metatarsal bone and the center of the calcaneus. This will help to create a diagonal relationship of pressure across the foot that will keep your ankle in a neutral position, neither supinated nor pronated.
10.26 DANDASANA
Applied Practice 2: Foot Position in Seated Forward Bends
Prop: 1 nonskid mat
Take Care: Avoid this practice if you have disc disease in your lower back.
SIT ON YOUR nonskid mat in Dandasana (Figure 10.26). Place your first metatarsals together and your heels slightly apart. Now notice the angle of the first metatarsals. While keeping them together, slightly evert the feet, that is, press the first metatarsals away from you and draw the fifth metatarsals toward you. This should make the bottom of the feet a bit uneven.
10.27 PASCHIMOTTANASANA
However, when you slightly evert the feet in Dandasana, notice how that action affects your whole lower extremity, causing it to roll slightly internally, the knees to straighten, and the inner calf to press the floor. This position is neutral for the lower extremity in forward bends. Maintain this position of the feet as you bend forward with an exhalation into Paschimottanasana (Figure 10.27). Remember to keep pressing your first metatarsal bones forward as you descend into a forward bend; imagine that they are leading you into the pose. Remember this position of the feet in all seated forward bends.
For Teaching
10.28 TADASANA
Applied Teaching: Foot Position in Tadasana
Prop: 1 nonskid mat
Take Care: Stand on an even surface.
HAVE YOUR STUDENT STAND in Tadasana on a nonskid mat (Figure 10.28). Suggest that he place his feet about 6 to 8 inches apart for the purpose of this lesson. First observe the lines along his fifth metatarsals. Make sure that he has placed the lateral borders of his feet parallel to the edges of his mat. He will likely need to move his heels externally to create this line. Most students stand with their heels too close together and thus in a position of external rotation of the thigh, leg, and foot.
Notice the general appearance of his foot, the shape of the arches, and if the toes are straight out or if the first toe is abducted and the other toes adducted. Now move behind him and observe the Achilles tendons. In an aligned foot, the Achilles tendons are vertical. You may want to suggest that he move the feet in what ever way is necessary to create a vertical line with the Achilles.
Now observe his medial and lateral malleoli. Are they parallel to the floor? If not, have him shift his weight or modify his foot position to make this happen. Finally, after asking permission to touch, you may want to stand behind him and press down firmly on the tops of his shoulders to see if he can easily bear your weight. If the student has aligned feet, he will bear this weight with no effort.
LINKS
Young children often appear to have flat feet because they have extra fat in their arches. As they mature, the natural arch usually appears. However, if you are concerned that a two- or three-year-old does indeed have flat feet, have the child examined by a health care professional.
With yoga games, the 5-minute class, relaxation games, and more, Create a Yoga Practice for Kids, by Yael Calhoun, M.Ed., M.S., and Matthew R. Calhoun (Santa Fe, NM: Sunstone Press, 2006), makes yoga fun for children and their parents and teachers.