Essential Foot and Leg Anatomy Every Yogi Needs to Know

Are common cues in standing poses wreaking havoc on your knees, sacroiliac joint, and lower back? Follow this anatomy advice to find better alignment from the ground up.
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Learn how to protect the knees, sacroiliac joint, and the lower back with this anatomy advice from Tom Myers. 

Learn how to protect the knees, sacroiliac joint, and the lower back with this anatomy advice from Tom Myers. 

Yoga teachers almost universally advise their students to place their ankles and big toes together or line up their feet under their hips with the outside edges parallel to the edges of the mat—in Tadasana (Mountain Pose) or Utkatasana (Chair Pose). The most anatomically inclined teachers urge students to align their feet so the second toes are pointing straight forward, positioning the tibias (shin bones) relative to the feet.

While aligning your feet in these ways may seem like a good idea, especially if you are splay-footed or pigeon-toed, it could cause long-term damage to your knees, other joints, and lower back. Here’s why—and how you can avoid it.

See also Anatomy 101: Why anatomy training is essential for yoga teachers

Foot and leg anatomy

foor and leg anatomy

Learn the essential foot and leg anatomy to help with your yoga practice.

For Teachers: To check for rotation within the knee, lightly pinch the inside and outside edges of your student's kneecap with your thumb and forefinger. Put your other forefinger right on the tibial tuberosity (the bump on the top front of the shin bone). The distance from here to the edges of the patella, where your fingers are, should be the same.

Your legs technically start from your 12th ribs, which sit beside your lumbar (lower) vertebrae. They include the psoas and quadratus lumborum muscles as well as the rest of the pelvic muscles that move or stabilize the hip joints.

The feet and legs are constructed as a series of hinge joints, known as single-degree-of-freedom joints, alternating with rotational (multiple-degree- of-freedom) joints.

The balls of your feet are five joints that together act as a hinge when you go on tiptoe. Above them is the rotational joint under your ankle: Rock your feet in and out from collapsed pronation (an exaggerated rolling in of the heel toward the midline) to locked-up supination (heels roll out) to feel this joint.

The upper ankle joint is also a hinge. From a standing position, bend your knees and bring them back to locked to feel your lower legs hinging over your feet from dorsiflexion (a decreased angle between your foot and shin) to plantarflexion (an increased angle).

Above that, in the lower legs, there is a small amount of rotation between the tibia and fibula, the bones between the knee and ankle. Flex one knee so that you are on the ball of your foot, and swing your heel in and out, like grinding out a cigarette, to feel this rotation.

Keep moving up your leg: The knee itself is constructed as a hinge. The ball and socket of the hip can, of course, move in multiple directions. The next link in the joint chain is the sacroiliac (SI) joint. To identify this joint, feel the prominent bones at the dimples at the bottom of the lower back. The SI joint, also constructed as a simple, one-degree-of-freedom hinge, starts about an inch in front of those. The sacrolumbar joints, where the spine sits on the sacrum, allow for some rotation.

Rotational joints are limited by bone shape, restricting ligaments, and overly tight muscles. But the range, interplay, and adaptability in rotational joints are greater than in hinge joints—which are limited to one dimension.

See also Anatomy 101: Are Muscular Engagement Cues Doing More Harm Than Good?

What happens when you focus on the feet?

Think about hinges such as those on the screen door of a porch. Each hinge works fine on its own as long as the screws are tight. It opens and closes, flexes and extends, and can continue to do so for years without repair. But if two hinges are misaligned, they are unlikely to last more than a few months before the door is bent, the screws tear loose, and the frame gets chewed up.

Now apply this to your legs: When you align your feet, the toe hinge and the ankle hinge will work like those of a good screen door. But your knees and lower back may be pushed into misalignment by aligning your feet—and that might in turn cause trouble for your knee, SI joint, and lower back, especially as you challenge them with more difficult asana.

To prevent this, most practitioners will be better served by aligning their knees under their hips and back and letting their feet fall where they may.

Hear me out: If you line up your feet but one or both knees are twisted on top of this (see the assessment below), you are misaligning the hinges on the screen door and risking long-term trouble. Think of walking: If you aligned your feet as you walked, your knees and lower back would operate like those misaligned hinges and start wearing down faster than they should, with bones pressing and grinding on cartilage unevenly. Instead, align each knee so that the patella (kneecap) faces forward. This way the important hinges above—in the hip, pelvis, and lower back—will also be in alignment. Align your feet, and there is no such guarantee.

How to check your leg alignment

Of course, if your feet, ankles, knees, hips, and pelvis are all truly in a line, then there is no problem to solve. Here’s how to find out if that applies to you:

Stand in front of a mirror and line up your feet so that the second toes are facing forward, but you are otherwise in a relaxed standing posture, not forcing it. Does your pelvis lie square to the mirror? Put your fingertips on the front of your hip bones, and look down to check. Remember, no forcing.

Now look at your knees. Are your kneecaps also directly aligned with the mirror, like headlights? Or are they headed in or out compared with the joints above and below? As you bend each knee, does the center of the kneecap go directly out over the second toe, or does it head off somewhere on its own? If the latter, trouble could ensue if you work from artificially aligned feet. Instead, line up your knees and work from there.

If you are thinking, Oh, I’ll just continue to line up my feet and simply turn my knee until it’s straight, to train it into alignment—don’t do it. Pulling your medially rotated knee into alignment usually strains the hip in lateral rotation and locks the lower ankle joint into supination—not a good solution, as it just sets you on a course for a different set of problems.

For teachers: To do a more precise check for rotation within the knee, get down and lightly pinch the inside and outside edges of your student’s kneecap with your thumb and forefinger. Put your other forefinger right on the tibial tuberosity (the bump on the top front of the shin bone). The distance from here to the edges of the patella, where your fingers are, should be the same.

If they are not the same (and it is more common for the inside line to be longer and the outside line to be shorter), the knee is misaligned. Have this student work with the kneecap straight forward until you (or a bodyworker, physiotherapist, or osteopath) can get this alignment restored. 

About the Author
Tom Myers is the author of Anatomy Trains and the co-author of Fascial Release for Structural Balance. He has also produced more than 35 DVDs and numerous webinars on visual assessment, Fascial Release Technique, and the applications of fascial research. Myers, an integrative manual therapist with 40 years of experience, is a member of the International Association of Structural Integrators and the Health Advisory Board for Equinox. Learn more at anatomytrains.com.