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the SPINE

More than any other part of the skeleton, the spine is directly involved in every asana. 

 

We spend a lot of time finding our centre  allowing us to move efficiently and effectively on the mat. With greater and more stable range of motion in the spine, we experience more ease and sensory awakening throughout the entire body. 

 

Weakness in the support of the spinal column is a leading source of distraction in sitting meditation. When our spines are unbalanced, we begin to see a variety of problems: lordosis, kyphosis, scoliosis bulging or herniated discs, and other painful conditions that compromise the delicate balance, stability and mobility of the spine. 

 

Viewed from the side, there are four primary curves to the spine, which help to distribute the stress of being an upright, bipedal, walking mammal: these 4 curves correspond to different regions of the spine the cervical spine (neck), the thoracic spine (the chest), the lumbar (lower back) and the sacral (tail). How much each segment curves is highly variable between individuals, and this variability is normal. 

THE design

1 : FACET JOINT | 2 : INTERVERTEBRAL DISC | 3 : VERTEBRAL BODY | 4 : TRANSVERSE PROCESS | 5 : SPINOUS PROCESS 

 

The spine consists of stacks of round bones (3) with fluid-filled discs of cartilage between them (2), which provide shock absorption and allow for movement by maintaining space between the bones. (In deep forward bending (flexion) the front of the disc compresses as the posterior side of the disc swells. The reverse happens in backbends (extension). In side-bending (lateral flexion) poses, one side compress the other side swells.) The space is also for the nerves, that branch off the spinal cord, sending and receiving information to and from most of the body. 

 

In addition to the round flat part (or body) of vertebra, there is also an awkwardly shaped area that sticks out in many directions behind it (4 & 5). These oddly shaped bones form the amazing ring that protects the critically important spinal cord. The bits of bone that shoot off sideways and backwards, provide attachment points for the muscles. They also allow for and restrict movement in certain directions. 

 

There are four facet joints (1) associated with each vertebra. A pair that face upward and another pair that face downward. These interlock with the adjacent vertebrae and provide stability to the spine. The range of motion of each vertebral joint is determined by tension in the soft tissues around the joint (the joint capsules, ligaments, muscles and fascia) and by compressive blocks between the various bony projections (processes). 

The ultimate limit of vertebral joint movement is reached when the vertebrae come into contact with each other. When the spinous processes “kiss” their neighbours, or when the facets press together, no further movement is possible; this compression is an ultimate limit to flexibility. Due to the large range of human variability, some people reach these final compression limits far more quickly than others. 

 

MOVE the spine

 

Flexion 

Extension 

Rotation 

Lateral Flexion 

‘Elongation & Contraction’

Axial Approximation  & Distraction

 

These movements are done more easily in certain spinal segments than in others. The lumbar spine is designed to flex and extend far more than it can twist; the thoracic spine can twist much more easily than it can flex and extend; and the cervical spine can move in all directions with equal facility but is limited in how much of a load it can bear. The neck is designed for mobility more than stability, while the sacrum and lower back are designed more for stability than mobility.

 

The vertebrae are numbered from top to bottom in each segment. 

cervical (neck)

C1-C7

 

They are the thinnest and most delicate vertebrae but offer great flexibility — the most mobile segment — designed to accommodate a large range of movement of the head. 

 

Ligamentous and muscular structures surround the cervical segment on all four sides, providing stability, support and allowing fine control over these movements. The cervical vertebrae are not often a target area in yoga asana because it’s pretty easy to move our neck around.

 

Due to the neck’s relatively small bones, the neck is susceptible to injury if movements are accompanied by too much weight or load on the head. As long as these two principles are followed, the risk to most necks should be minimised :

 

  • When at extreme ranges of motion, minimise the loads upon the head and neck.

  • To strengthen the head and neck (i.e., place a load on them) when they are close to a neutral alignment.

 

Plough Pose (Halasana) requires both a large load placed on the neck and extreme flexion, while Raised Fish Pose (Uttana Padasana) requires a large load and extreme extension. Rabbit Pose (Sasakasana) places a lot less load on the neck while it is flexed than Plough Pose does. Camel Pose (Ustrasana) is a neck extension posture that is bearing only the weight of the head, making it safer for the neck than Fish Pose.

 

Some movements of the head and neck for some people do lead to problems, such as dizziness, headaches, tinnitus or lightheadedness. If these symptoms arise, the provoking movements should be avoided. Let your students know that they might experience unwelcome sensations while twisting or moving the neck. By giving them advanced warning and permission to avoid the movements, students are far less likely to remain in a position while problems arise.

 

thoracic (chest)

T1-T12

The thoracic spine has two key functions: 

 

  • to transmit forces from the upper to the lower body and vice versa;

  • to allow respiration. 

 

The thoracic vertebrae are larger and stronger than cervical vertebrae but less mobile. Each vertebrae here forms joints with a pair of ribs, forming the sturdy rib cage. The ribcage facilitates breathing while restricting movement in most directions. The spinous processes of the thoracic vertebrae point inferiorly to help lock the vertebrae together.

 

Extension and flexion are the most severely restricted movements between each pair of vertebrae, followed by lateral flexion (side-bending). Rotation is the least restricted movement. While the range of motion between pairs of vertebrae is rather small, there are 12 vertebrae in the thoracic spinal segment, so some people do have considerable total movement available for the whole thoracic segment. Except in some very rare yogis and contortionists, the thoracic spine does not extend past straight. A lot of movement that is thought to be of the thoracic spine is actually movement of the scapula, clavicle and humerus.

 

 
 
 
 
 
 
 
 

KYPHOSIS

The prominent curve found in the thoracic spine is called kyphosis, which means “humpback” in Greek. The amount of kyphosis people have is variable: normally the thoracic spine exhibits a curve of 11–54°, with one study finding the average to be about 33°

 

The thoracic spine can flex a little, as in Child’s Pose (Balasana), or a lot, as in a seated forward fold (Paschimottanasana), but it rarely extends past flat, Cobra Pose (Bhujangasana).

 

  • Hyperkyphosis - normal kyphosis becomes greater than 45°

  • Hypokyphosis - a kyphotic curve of less than 20°

Hyperkyphosis can be caused by osteoporosis, degenerative disc diseases, spinal extensor muscle weakness, calcification (and so stiffening) of the anterior longitudinal ligament, or posture degradation, possibly due to changes in eyesight, inner ear balance and proprioception. The condition can be congenital or may develop over years of a chronically flexed posture. 

As the thoracic spine curves more deeply, body height is lost. Hyperkyphosis can cause someone’s centre of gravity to move forward, requiring compensation in other areas to maintain balance. Lumbar lordosis will increase, and the pelvis will tilt posteriorly. These accommodations will bring the line of the center of gravity back behind the femurs’ heads. While this will improve balance, it will also increase the stress on lumbar discs and vertebrae which can lead to degeneration. To maintain this posture, chronic muscular effort is required, which can also lead to chronic pain. Shorter hip flexors and pectoral muscles are a hallmark of this condition, but it is unknown whether short, tight muscles cause the condition or vice versa. Back extensions are proposed as ways to reduce hyperkyphosis. 

 

Hypokyphosis is less common. When the upper back flattens considerably due to the relative straightening of the thoracic spine, there is less space between the front and back of the chest, creating a “pancaking” of the heart and major blood vessels, which may lead to heart valve problems.

 

lumbar (lower back)

L1-L5 

 

The lumbar has the largest and the strongest of the moveable vertebrae, bearing more weight than the ones above. Due its location, it is subjected to compressive stresses as well as having the most flexibility. A dual role that makes this segment more susceptible to injury and strain. The spinal cord comes to an end between L1-L2, splitting off into nerve roots and gather together lower down to form the sciatic nerve. 

 

The lumbar spinal segment is normally formed of five vertebrae, however 3.4% of people have only four and another 3.4% may have six: that is one person out of 30 who may have an extra lumbar vertebra and one out of 30 who has one less.

 

While the spine is designed for stability and mobility, when the spine is bearing a load it is safer and healthier to stabilise the lumbar through co-contraction of the core muscles: the abdominals and the erector spinae. If our goal is to enhance the range of motion of the spine, this should be done when it is not bearing a load.

 

LORDOSIS

The prominent curve found in the lumbar is called lordosis, which means “backward bending.” The amount of lordosis is highly variable, but normally the lumbar exhibits a 29–69° curve, with one study finding an average of about 49°. While too little lordosis is not good, too much is not healthy either.

  • Hyperlordosis - more than average curvature

  • Hypolordosis - less than average curvature

Determining who is which is not easy without imaging the spine, as posture and positioning of the pelvis can create a mask for lordosis.  As we age, some people lose lordosis and yoga can enhance the amount of curve. If someone exhibits either hyperlordosis or hypo, they are considered flawed and must be corrected. That may be true, but not necessarily so. Some people adopt these postures for benign reasons and don’t need to be fixed. Others, however, may suffer from chronically maintaining these positions

 

sacrum coccyx (tail)

S1 - S5 -

 

SACRUM: The sacrum, a single bone in the adult skeleton that is formed by the fusion of 5 smaller vertebrae during adolescence. The sacrum is a flat, triangular bone found in the lower back and wedged between the 2 hip bones.

 

COCCYX: The coccyx, a single bone in the adult skeleton, is formed by the fusion of 4 tiny vertebrae during adolescence.While most people have a coccyx made of 4 fused vertebrae, the coccyx may consist of as few as 3 or as many as 5 vertebrae. The coccyx is often referred to as the human tailbone.

sciatic nerve

The sciatic nerve emerges from several smaller nerve roots between L4 and S3. When these roots join together, the whole nerve can be as large as 2cm in diameter. It remains one thick cable until it reaches, usually, the back of the knee, where it divides into the tibia and fibular nerve. In most, the sciatic nerve emerges from the sacrum, under the piriformis muscle, however it sometimes runs above and sometimes it penetrating through.

SCIATICA

Sciatica refers to pain that radiates along the path of the sciatic nerve. When and where pain may arise would depend on the routing. Some poeple may experience the pain of sciatica due to the way their sciatic nerve runs through their buttocks. More superficial placement of the nerve may subject it to more stress and pressure than deeper placement. The nerve roots may be closer to bony growths making impingement more likely. 

 

SCOLIOSIS

 

Scoliosis is the Greek word for “crooked” or “bent.” Scoliosis may appear in several ways. The bend can be in the lower spine (lumbar scoliosis), the thoracic spine (thoracic scoliosis) or both areas (thoracolumbar scoliosis), or it may be more complicated, with double or multiple curves. Scoliosis is not simply a side bend to the spine but also a rotation. This is very noticeable when the person with a lot of scoliosis folds forward: a costal hump is formed by the left rotated ribs rising up posteriorly

 

Few of us have a perfectly symmetric spine, and that is normal, but when the curvature of the spine as seen from behind exceeds 10°, the spine is considered officially scoliotic. The reported rates of scoliosis of the population vary; if the actual rate were 5%, one person in a yoga class of 20 would have scoliosis.

 

A lot of the time we don’t know why it occurs, it may be congenital or genetic, due to neuromuscular problems or disease. Many researchers believe chronically poor posture can cause or contribute to a worsening of scoliosis.

 

The treatments recommended for scoliosis vary with the degree of curvature. Sometimes no interventions are needed, for others bracing is recommended, for some exercises and postural re-education are offered, and then there’s surgery.

 

When it develops, scoliosis causes one side of the torso to shorten, tighten and strengthen, while the opposite side lengthens and weakens. Since the convex side (the open left side) is too long and too weak, it makes sense to shorten and strengthen this side. Since the concave side (the closed, right side) is too tight and too short, it makes sense to lengthen it but not strengthen it any further. A posture such as Side Plank (Vasisthasana) fits the bill nicely. The lower (left) side of the torso is contracting and strengthening. The upper (right) side is lengthening but is not bearing much load, so it is not becoming stronger. Research has displayed a marked improvement.

 

DISC injuries

BULGING DISCS - Where the cartilaginous disc is compressed and the pressure forces the cartilage and the nucleus to bulge either in one direction or equally in all directions. How far the bulge protrudes and the force applied to the disc will determine wether there is pain. If the disc sticks out far enough to press on the nerve root it will cause sensation further down that nerve. 

DISC HERNIATION - the difference between a bulge and herniation is that the area of the disc that protrudes is weakened or possibly has tears in the fibers of the cartilage. Herniations are often associated with back pain because they are likely to push out far enough to press on the nerve root.  

RUPTURED DISCS - the cartilaginous ring or disc itself tears from its outer wall to its centre, where the nucleus and fluid are. The fluid leaks out from the disc. As a result of the fluid loss, the space between the bones is reduced. The purpose and function of the disc is compromised, which can result in compression of the nerve roots, not only by the disc but by the vertebrae themselves. 

 

 
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