The major functions that the skeleton is responsible for;
support - providing framework/shape
movement - via the joints
protection - of the internal organs and systems
production of blood cells - via bone marrow
storage of minerals (calcium and iron)
endocrine regulation - osteocalcin for blood sugar regulation
The form and shape of a bone reflects its function.
SHORT BONES - provide stability & small complex movements. Carpals & Tarsals
LONG BONES - support the weight of the body & provide movement. Femur & Humurus
SESAMOID BONES - bones embedded in tendons. Patella
IRREGULAR BONES - often have a complex shape & protect organs. Vertebrae & Pelvis
FLAT BONES - provide organ protection & area for broad muscles to attach. Skull & Scapula
Bones are living tissue and respond to the healthy stress of weight bearing and adequate compression. Therefore it is important to move them and place them in certain ways that allow them to remain strong, supple and healthy so they can continue to effectively perform their necessary functions.
Stress in bone causes bone building cells called osteoblasts to initiate new bone and bone clearing cells called osteoclasts to consume and recycle calcium from old or injured areas of bone. Osteoblasts are allowed to lay down new bone anywhere they like as long as it is within the periosteum (dense fibrous membrane covering the surfaces of bones). The osteoclasts may eat at any bone, except those parts that are mechanically stressed. This allows bones to resist individual forces coming through it but also capable of changing to meet new forces when constantly applied.
In healthy bone, a delicate balance exists between the cells that build bone mass and the cells that break down old bone in a continual remodelling cycle.
Yoga will influence the health of our bones and strengthen them but once past puberty and bones are developed we cannot permanently bend them or lengthen them. We can change the bones relationship inside us by adapting our convective tissue through yoga, however ultimately once we've undone tensile restrictions, bone hits bone and we reach our limits. We can discover where we compress but our yoga practice will not change where we compress.
Our skeleton is made of more than 200 bones. We can group bones together functionally into segments. A segment is a part of the skeleton that we cannot isolate any further, they move together as a group.
The Skeletal Segments consist of:
Segments of the axis of body;
Segments of the arm;
Segments of the leg;
200HR TEACHER TRAINING
The extraordinary ability to respond to demand accounts for the wide variety of joint shapes across the human spectrum. Dramatic differences can be seen in the above categories of bones. Besides the obvious size and length variations some bones are twisted 40 degrees backward or rotated 30 degrees upward. These differences might remain a mere curiosity but when these skeletal differences are coupled with the idea of compression it usually turns a student’s yoga world around. Because all of our bones are different, all of our joints compress at different angles.
Architectural principles start from the premise that all structures, including our bodies, are a balance between stretching forces and crushing forces, or “tension and compression”. When we practice Yoga asana the fundamental distinction to make is : “Are the physical restrictions I am feeling tension or compression?” Tension is due to the stretching of muscle or connective tissue but compression can be determined by the shape of our bones.
- The shape of our bones determines the range of motion of the joints.
- The size and proportion of the bones determines how safely and effectively we can do the asana.
Skeletal variation shows up everywhere in yoga, in every pose. The more you focus on where you fingers and toes should be, the more you are potentially compromising the bigger joints of the body closer to you spine. Two people standing in exactly the same way -- with feet together, facing forward -- may be feeling it differently in their hips because of their skeletal differences.
1. When we practice asanas we move our joints.
2. When we move our joints our bones pivot away from each other.
3. Because the bones are moving apart tissues are stretched.
4. At first our limits of motion are determined by how much we can stretch.
5. But the ultimate limit to our range of motion is compression.
6. Compression is due to the shape of our bones.
TEACH SKELETAL DIFFERENCES & COMPRESSION
Compression is not a native conception to most yoga students. Even if a student senses a “natural limitation” in their movements they will not use the word “compression” to describe it. The closest they will come is “I don’t bend that way.”
Time and again I have seen students unable to tilt his pelvis forward in a forward bending posture because the trochanter of their femur is compressed. When I ask them where they feel the restriction they are not sure what to say because they don’t feel a “stretch” in their groin or hamstrings. They are not in pain. Pushing on them doesn’t bother them much. They just “can’t do down”. - Paul Grilley
Virtually all the metaphors of present day yoga instruction are tensile. "relax the muscle tension, breath into it, soften up the tissue, let go, release tension, make a space – let the bones move apart." Why limit our conceptions to tensile metaphors? For the vast majority of us who have practiced yoga for several years the restrictions we experience are compressive, not tensile.
ARCHITECTURAL STABILITY versus MUSCULAR STABILITY
Being able to stack the bones right on top of each other has benefits. Architecturally, when the bones are completely aligned, the stresses of the weight in the posture are taken by the full column of the bones, not by the joints nor by the muscles. In this case the muscles are used simply to keep the bones aligned, not to support the weight of the body. Bones are great at supporting weight. When we are not architecturally aligned, however, the bones are not doing this job, and more of the stress of the body’s weight falls onto the muscles and/or the joint and its ligaments. Muscular stability is harder to maintain: it is work, but that may be quite desirable. The big difference will be time: when we are stacked, we can stay much longer in a pose than if we have to rely on muscles or ligaments.
By understanding our skeleton, we can potentially stack our bones and move in a safe way that will keep us injury-free and practising yoga for the long-term.