These are notes from our first class on The Anatomy of Asana: The Leg, the lower appendicular organ. Those in the teacher training program may print out these notes for your notebooks, or otherwise keep them for study. They are not the notes of a professional anatomist, and are incomplete in listing all the muscles and even all the bones of the lower extremity (you go find where the sesamoid bones are). You will find them useful anyway because they describe the major muscles, the prime movers of the leg, and they give you a good idea of what each can and can not do. Know that many muscles serve ‘helper’ functions also, separate from their primary function.
These notes are free for your use, and I would greatly appreciate feedback—if you note inaccuracies or insufficient information, please let me know and I will work to make corrections and repost. I enjoyed teaching that class last Saturday morning. I at least had fun. I thank my teachers for whatever came out right in the presentation, and I take all credit for my errors.
LEG BONES
1. General note about bones: Most bones are not actually smooth or uniform on their surface. They have parts that look knobby, roughened, ridged, or angled, and other areas that look relatively smooth. Those knobs, ridges, angles, and roughnesses are all there serving as attachments of muscle, ligament, or tendon to the bone. These textured and three-dimensional surfaces are pronounced to make a strong and useful surface to anchor strong muscles, and their roughness increases the surface area available for the muscle or tendon or ligament to attach.
And a small digression: As an anthropology student I had the opportunity to work in a bone lab where we measured the bones of about 300 peasant farmers who lived in the 13th century in what is now the Czech Republic, and whose skeletons were excavated from a cemetery and now are cared for and studied by anthropologists like my teacher. Our collection was representative of an entire village of men, women and children, of all ages up to around 45 years (that was old back then), as best we could determine, across a hundred years or so of time.
One thing I had already known is that when you are a medieval peasant or serf, you begin working as soon as you are 5 or 6 years old, old enough to carry things and hold and use a tool. If as a peasant a large percentage of your crops of flax, oats, barley and wheat that you grow go to the overlord of the territory as tax or tribute, you want as many hands as possible in the fields planting and harvesting, so you can keep a little more to see your family through until the next harvest. It was normal for children to have pretty short childhoods.
At around 10 or 11 years of age, the articular surfaces (the part that forms joints) of bones complete their formation, though the long bones of arms and legs can keep lengthening as the individual gets taller in adolescence, and they become stronger with use. The new thing I learned was that when any body begins strong work during the bone growth phase, it makes the bones that are in heavy use much more robust in general, and those knobs and ridges on the bony surfaces become stronger and a bit larger. The influence of strong activity on the bones is crucial to the shape and structural integrity of bones.
Our measurements showed that every single person in that collection, save the very young, had a right arm as much as 4-5 centimeters longer than the left arm, and measurably larger in diameter as well. Everyone in that part of the world at that time was right-handed, as left-handedness was considered a devilish thing. Everyone, therefore, swung the scythe, pick, or shovel; or fetched and chopped firewood; or did every other job to sustain their lives, all using the dominant right hand, the left side supporting and assisting. No machines (that were not human powered). The right arms and shoulder bones of everyone, set to hard work in childhood, were made to develop more under the stimulation of contracting muscles and regular impact. You can see this in professional athletes in the present day—tennis players, for example, who began thwacking balls back and forth every day starting in childhood. As adults those larger racket arms are visible, but I used to think it was only the muscle that was extra developed. I learned in the bone lab that it is the bone too.
Think of it this way: the entire body is shaped by our lives, right down to the bone. Every action leaves an impression not just on the mind, but the body as well. To the bone.
2. Here is something I had no time to mention in class, but which is important not to leave out:
Types of joints in the body:
a. Fixed:
Fibrous (ex. sacro-iliac joint)
Cartilaginous (ex. Sterno-costal joints)
Bony (ex. The suture joints of the skull bones)
b. Synovial (freely moving, and they have the lubrication of synovial fluid to help):
Pivot (ex. between 1st and 2nd cervical vertebrae)
Hinge (ex. joint between tibia, fibula, and talus bone of ankle)
Ball and Socket (ex. hip or shoulder)
Saddle (ex. between the trapezium bone of the hand and the 1st metacarpal bone)
Gliding or Plane (between some tarsal bones and also tarsal-to-metatarsal joints)
Ellipsoid or Condyloid (ex. between femur and tibia (knee), metatarsal-phalanx and all phalange joints)
You can search in your books for how the movements of these joints work. That will be your study. We will look at this in the next Anatomy of Asana class in October.
3. The Bones
[Pelvis]: The pelvis is designed simultaneously and in no particular order, a) to provide support for the spine and trunk, b), to be a basin containing the organic body and all its functions, and c) to anchor the means of locomotion and stability to the spine and organic body. It is not a leg bone, but it is the anchor of the leg to the rest of the body. The pelvis is the Grand Central Station of transportation and support of the bony structure and the vital organs. Note, the work of the leg has enormous effect on the vital organs, and muscle movements and tensions can assist or hinder their functioning.
Femur:
See the bone on our skeleton and then palpate the parts that are feel-able: the greater trochanter and the distal end at the knee. It is designed for weight bearing and communicating effort and force from our core outward, and stability from the ground beneath us upward.
Articulates with a deep ball and socket joint to the pelvis. This type of joint structure allows for great range of motion as we will see.
Patella:
We bend the knee to feel and see the outlines of the patella, see it on the skeleton, and then straighten the knee to feel how mobile it is, and how it slides around a bit, more medially than laterally. The patella is a major stabilizer of the knee and protector of the joint from impact. It is enveloped in the fascia forming the distal end of the quadriceps muscles and those tissues attach at the tibial tuberosity, at the proximal anterior surface of the tibia.
Tibia:
The principle weight-bearing bone of the lower leg, the one which articulates with the knee. We attempt to palpate the joint to find the medial and lateral condyles of the bone, and how they meet their partner condyles on the distal femur. Note that at the ankle, the tibia carries more body weight into the foot than the fibula bone, though together they form the upper part of the ankle joint and both articulate with the talus bone.
Fibula:
We see this bone on the skeleton, noting that it does not form part of the knee joint proper, and that it does form the lateral part of the ankle structure but that muscles from the foot and also the thigh are attached to it.
We observe the medial and lateral malleoli of the ankles, which are formed by the distal ends of the tibia and fibula, respectively. We see how the fibula’s distal end at the lateral malleolus is set lower to the ground than the tibia. We note that lower positioning inhibits somewhat the pronation of the foot, whereas supination is easier. Note also that this is why more people sprain their ankles on the lateral side—it is easier to supinate far enough to roll off the foot and injure the tissues of the joint by overstretching. Not so easy the other way.
Ankle bones (tarsal bones)
a. Inner: from the proximal end of the 1st metatarsal comes the
cuniform,
navicular,
talus,
medial malleolus (tibia),
calcaneus (heel)
b. Central:
dome of talus, which can be palpated on the medial side of the foot and is also listed above, which together with the tibia and fibula form the ankle joint surface…
two central ankle bones (also cuniforms) attaching to the 2nd and 3rd metatarsals.
c. Lateral:
From the proximal end of the 5th metatarsal (where we note the protruding styloid process), we meet with the cuboid bone, and on it the peroneal tubercule where the peroneus muscle turns a corner and heads toward it’s attachment on the underside of the foot, and then the calcaneus, or heel bone.
Foot bones: metatarsals and phalange bones
From the medial side the first metatarsal has two phalange bones, and is a large bone relative to the others.
There follow the second through fifth metatarsals, each of which have three phalange bones attached.
4. Muscles and their Groupings:
4a. Hip Flexion
Iliopsoas (primary, polyarticular—moves more than one joint.
Sartorius (also abducts and externally rotates femur)
Rectus femoris (the other quadriceps-- vastus medialis, v. lateralis and v. intermedius-- are part of the knee extensor group)
4b. Hip Extension
Gluteus maximus
Hamstrings:
Biceps femoris on lateral side
Semimembranosis on medial side
Semitendinosus on medial side
4c. Hip Adduction
Gracilis
Pectineus : adducts, flexes and internally rotates hip
Adductor longus
Adductor brevis
Adductor magnus adducts, most posterior of adductors; and extends thigh (u.dhanura) helps with external rotation of L leg in parsvakona or other standings
4d. Hip abduction
Gluteus medius
Gluteus minimus
4e. Hip internal rotation
Tensor fascia late (polyarticular): note that it joins into the thick strong band of fascia we call the IT (Ilio-tibial) band. This allows it to do many jobs: it helps with internal rotation of the femur, knee extension, abduction of hip and supports the femur lining up correctly on the tibia in standing upright.
4f. Hip external rotation
Piriformis: the main one of this group. Attaching at the sacrum and greater trochanter. Strong.
Quadratus femoris: deep and most distal of rotators. Helps piriformis in external rotation.
[Psoas helps not just with flexion but also external rotation. It is involved in everything as lumbar stabilizer and flexor and rotator helper. In brackets because it is mostly in the pelvis, but does its job with the leg from there. It also does many other jobs too, as we shall see.]
4g. Knee extension
Primary: quadriceps
Vastus medialis
Vastus lateralis
Vastus intermedius
4h. Knee flexion
Primary: Hamstrings
Semimembranosus
Semitendinosus : lie prone, bend knee, rotate leg internally and then lift the leg off the floor to feel the two spindles of tendon for these two hamstring muscles stand up. Both semimembranosis and semitendinosus are attached to the tibia on its medial edge.
Biceps femoris: lie prone, bend knee, rotate leg externally and lift the leg off the floor to single out the muscle. Note that b. femoris is the one of the hamstrings that is attached to the fibula.
4i. Knee internal and external rotation (10 deg each way)
Muscles cannot be isolated as a special group, but knee rotation is part of the function of the femur’s extensor and flexor muscles
Ex: with knee flexed, biceps femoris, attached to the fibula, can be contracted
to externally rotate knee.
Internal rotation through semimembranosus and semitendinosus feel with knee bent sitting on chair.
4j. Ankle: note: must distinguish between ankle flexion/extension and foot extension/flexion.
Dorsiflexion (plantar extension):
Plantar flexion (dorsal extension):
Subtalar motion (meaning below the ankle joint):
Inversion (pronation)
Eversion (supination)
Forefoot adduction
Forefoot abduction
4k. Toes
Flexion
Extension
5. Poses with examples of movements: (note, R is the right leg and L the left. Imagine the first side of the pose with the R leg always being the ‘front’ leg or the lifted leg, and the left the ‘back’ or standing leg.)
Tadasana: neutral extension of hip and knee; dorsiflexion of ankle and neutral extension of the foot (foot means the forefoot and is distal to the ankle). Most beginners need work to actively to come to neutral in the knee and hip. That word “neutral” does not mean the easy resting position with the muscles inactive and ‘neutral’; rather, it means the position where the joint is in a neutral position, not flexing, extending, rotating, ab- or adducting, extending or retracting. Some people are pre-set in a hip flexion (their ‘neutral’ is a slight or pronounced flexion), and have great trouble standing fully upright.
Garudasana : hip: adduction, internal rotation (resisted), flexion at hip and knee. Knee: flexion, slight external rotation on the top leg. Ankle/foot: lifted foot is pronated with slight plantar flexion; standing foot is in tadasana, dorsiflexed at ankle, extended foot.
Vrksasana: bent leg hip: external rotation, abduction and flexion. Bent knee: flexion and slight external rotation. Straight leg: neutral extension, and remember, to get to neutral in the joint we have some work to do to extend the front hip and use the abductor muscles to make the standing leg stay at vertical/neutral.
Utthita Hasta padangusthasana: Lifted leg: flexion at hip, extension at knee, awakening adductors only to resist lateral drift of leg, plantar flexion of foot, extension of toes. Standing leg: neutral; similar work to vrksasana and tadasana.
Trikonasana: R leg: external rotation, abduction and flexion at hip, extension at knee. Foot is plantar flexed and pronated to keep inner/medial side of foot down. L leg: Knee faces forward essentially, so depending on the condition of the hip joint, one must internally or externally rotate to get there. Also extension at hip and knee. Foot is dorsiflexed and somewhat supinated to get the outer foot grounded.
Vira II to parsvakonasana: R hip: weight bearing external rotation, abduction, and flexion; knee external rotation, and flexion; foot neutral or slightly supinated to make the foot neutral on the floor. L hip: extension, more abduction than trikonasana; knee extension; ankle plantar flexed and slightly supinated to keep weight neutral on foot.
Parsvottanasana : R: internal rotation, flexion of hip, extension of knee. Foot: plantar flexion and slight pronation to keep foot neutral L: hip extended (relatively and when upright), knee extended, foot dorsiflexed.
Vimanasana flexion of front hip, extension of back hip and knee, not full extension of L hip
Vira I even more extension, can go to full extension
Prasarita padottanasana: flexion and abduction, and neutral rotation
Virasana: knee flexion, hip flexion, internal rotation of the entire leg, ankle and foot are plantar flexed and pronated to straighten out the angle between the ankles and feet. Toes are extended as much as possible.
Dandasana: hip flexion, knee extension: extensor muscles of hip (hamstrings) pressing/pulling down, ankles dorsiflexed, feet and toes extended
6. We did more poses in class, but you can try your hand at naming the movements of R and L legs in these poses. Some are review from class, some are new:
Utthita hasta padangusthasna
Adho mukha svanasana
Urdhva mukha svanasana
Ardha chandrasana
Triang mukhaikapada paschimottanasana
Setu bandha sarvangasana
Bharadvajasana I
Some of these have some tricky movements at the hips, so take care to practice the pose a bit and see what you feel as you name the movements of the leg.
Have a lovely and interesting time!