GOOD HEALTH COMES FROM A STRAIGHT SPINE AND A CLEAN COLON.
—HINDU PROVERB
DURING MY TRAINING to become a physical therapist, I spent a lot of time studying the spinal column, its bones, its nerves, and the kinesiological functions of this part of the body. In the evenings after classes, a group of us would sometimes stay a little late to avoid the evening traffic jam on the bridge and would spend our time studying together in a relaxed manner. One of the things we would do was to pick up an individual vertebra from a box we had in our lab and, without looking at it, attempt to identify not only the region of the spine it came from but which bone it was. We got pretty good at this game. While yoga teachers may not need this level of expertise, knowing as much as you can about the vertebral column and its functions will be of great help in your teaching.
Most asana are concerned with maintaining the health and movement of the spinal column. It is generally accepted by most teachers that the spine is not only at the core of our structure but also at the core of our practice. However, what surprises most teachers as they begin to study this part of the body in depth is how distinct each section, even each vertebrae, is one from the other. This section of Yogabody begins with an overview chapter on the column as a whole and then offers a chapter on each region of the spinal column.
BONES
The vertebral column, also called the spinal column, consists of thirty-three bones, not all of which are independently movable. Contrary to the proverb at the beginning of this chapter, the bones of the column are arranged in a series of gentle curves from top to bottom. These curves can best be seen from the sagittal, or side, view (Figure 3.1).
There are five sections of the column. The most superior is the cervical region, or neck, and consists of seven vertebrae. They are numbered, as are all vertebrae, from the top down. The next region is the thoracic spine, with twelve vertebrae; all thoracic vertebrae are attached to two ribs each. The lumbar spine and the sacrum each consist of five vertebrae, except the sacrum’s are fused into one curved bone. The coccyx is made up of three to five vertebrae and is commonly called the tailbone.
The vertebrae are named for their region, using the first letter of the region and numbered from the top down, like this: C1, T8, L4. These vertebrae would be the first cervical, eighth thoracic, and fourth lumbar, respectively.
The vertebral column has a variety of functions, including helping to holding us upright and providing an armature for the posterior wall of the trunk and ribs. Additionally these bones protect the nerves of the spinal cord and serve as the attachment site of muscles and ribs, thus helping to protect the internal organs.
The spinal column plays a major part in all of our movements, especially in the movements of asana. In yoga there are philosophical implications to the vertebral column as well as the more obvious anatomical and kinesiological ones. The spiritual energy of kundalini is said to lie curled like a sleeping serpent at the base of the spine. It is the awakening of this energy, as it travels upward along the sushumna, an esoteric canal at the center of the spinal column, until it reaches the highest center in the brain. When this happens, it is believed that the practitioner has attained the state of enlightenment.
However, from a structural viewpoint, the most significantly observable aspect of the column is that it is arranged in a series of curves, which can be easily viewed from the side, and is not a straight line. This series of curves allows for freer movement between the segments and improves the ability of the column to bear weight efficiently and act as a shock absorber. The vertebral curves are called “normal curves” by anatomists, thus underscoring their importance.
The thoracic spine at the rib cage area and the sacral curve below the waist are called primary curves because they are developed in utero. These two regions of the spinal column remain curved in the same direction throughout life. Both of these curves have their concavity anteriorly. Because the thoracic and sacral spines have their concavity anteriorly, they are said to exhibit a kyphosis. The word kyphosis refers to the curve itself; in the common vernacular, however, the word kyphotic is often used to mean too much of this type of curve.
The cervical curve and the lumbar curve are both called secondary curves because they develop after birth. These curves have their concavity posteriorly and are said to be lordotic. The term lordotic is often used to mean too much of a lordosis in one of these curves.
In utero the baby is in flexion, the direction of the primary (thoracic and sacral) curves. As the baby begins to hold her head up, the cervical curve develops; her lumbar curve develops while she is learning to stand. Because the secondary curves are developed and are the opposite of the curve of the column found in utero, they are less stable. It is much more common for yoga students to have problems with either the cervical or lumbar region than the thoracic or sacral, in part because of this lessened stability.
The secondary curves are said to be sympathetic curves. This means that when your student flexes his neck, he also has a tendency to flex his lumbar spine, and when he extends his lumbar spine, he often will extend his cervical spine as well. You can experiment with this. Lie on your back, knees bent, on your nonskid mat. Close your eyes and take a few easy breaths to relax and center. Now draw your lower back toward the floor, and notice your neck: it also flattens and lowers toward the floor. Extend your cervical spine by lifting your chin and increasing the curve, and notice what happens to your lumbar spine: it also extends and moves away from the floor. Remember the concept of sympathetic curves when you are teaching forward bends and back bends.
3.1 (LEFT) NORMAL CURVES OF THE VERTEBRAL COLUMN, WITH SAGITTAL VIEW OF PLUMB LINE
3.2 (ABOVE) CERVICAL, THORACIC, AND LUMBAR VERTEBRAE, SHOWING THE SHAPE OF THE BODY; SUPERIOR VIEW)
Each vertebra has a body, which is the largest single portion of the vertebra. The exceptions are C1 and C2. C1 lacks a body entirely, and C2 has a small, roundish body. When viewed superiorly or inferiorly, the vertebral bodies have a different shape in each vertebral region. In the cervical region, the bodies are oblong; the thoracic bodies have a heart-shaped form; and the lumbar bodies appear kidney-shaped (Figure 3.2).
The body is the main weight-bearing part of the vertebra. Note that the vertebral bodies increase in size, from cervical to lumbar, in order to better support the weight from above. The ends of each vertebral body are covered superiorly and inferiorly with a cartilage end plate. There is also an opening in the body to allow for nourishment from the blood supply. Remember, bones are living tissue and, as such, need oxygen and other nourishment.
C1, which does not have a body, is instead shaped like an oval or oblong ring. Embryologists tell us that the body of C1 migrates distally during embryological development and fuses with C2 to create a prominence on the anterior body of C2 called the dens, or odontoid process. The second cervical vertebra can then rotate on C1 around the dens.
The vertebral arch is the bony ring in the middle of each vertebral body and is the opening for the passage of the spinal cord. Note that the cord is located at the most protected part of the column. The anterior part of this circular structure, which connects to the body, is called the pedicle; the posterior portion of the arch is called the lamina.
From the lateral view, the inferior and superior vertebral notches, or bony arches, are apparent. The vertebral notch creates part of the opening for the spinal nerve to pass out laterally from the cord. There is a superior and an inferior vertebral notch. The vertebral notch from one vertebra fits together with the vertebral notch of the one below it. This is like placing the two halves of a doughnut together to make a circle. The circle it creates is called the vertebral foramen, or opening, through which the root of the spinal nerve of the spinal cord passes. Actually the spinal nerve root only takes up two-thirds of the total space in the vertebral foramen. The rest of the space is taken up by a protective envelope around the nerve root. This envelope consists of fatty tissue, loose connective tissue, and blood and lymph vessels.
The lateral transverse processes, or bony projections, are found on the lateral sides of the vertebrae. The transverse bony processes emerge between the pedicle and the lamina. These processes serve as the attachment points for muscles. Think of a transverse process like the handlebars of a bicycle. When you turn your handlebars to the right, the front wheel turns right. The opposite occurs, of course, when you turn left. The transverse processes of the vertebral column function similarly. When muscles on one side of the transverse process contract, they help to rotate the vertebral body.
The other process on the vertebral body points posteriorly; it is called the spinal process, and it emerges from the lamina. The spinal process is the knobby protuberance you can feel and sometimes see down the central “canal” of the column when you look at your student’s back. The spinal process serves as the attachment point for ligaments and muscles. It can be easily palpated. Try this.
Have your student get on all fours on his nonskid mat. As he exhales, have him lift and round his vertebral column. After asking permission to touch, run your fingers along his spine, feeling the pointed spinous processes. You may note that some are more prominent than others or that the spaces between them are slightly irregular. Or you may find that some seem rotated to one side.
Yoga teachers often express concern that the prominence of these spinal processes in forward bends is incorrect. This may not be totally appropriate. Some students may have more of a lumbar curve, so the processes are not as easily seen or felt. Others may have longer spinal processes, so that the processes are more prominent. It is more important to take into account the entire shape of the column and the positioning of the pelvis when accessing the health of a forward bend, not just the appearance of the spinal processes.
JOINTS
Each vertebral body has four flattened surfaces, called facets, on the posterior side, which are covered with cartilage to facilitate fluid movement and to protect the bony surfaces. Two face upward, the superior facet surfaces, and two face downward, the inferior facet surfaces. These are the sites where adjacent vertebrae meet to form a joint, the face joint. However, the sacrum only has two superior facet joints, and they join superiorly with L5.
The facet joints lie at different angles in each of the movable sections of the column. In the cervical region, the superior facets are at an angle of approximately 45 degrees, facing posteriorly and upward (Figure 3.3). The superior thoracic facets face backward but are more vertical than the cervical facets (Figure 3.4). The superior lumbar facets face medially, except the L5-S1, which face almost posteriorly (Figure 3.5). The change from cervical to thoracic facet angles is gradual, but the change from thoracic to lumbar facet angles is abrupt. (The unique features of the facet joints at the transitional segments—C7-T1, T12-L1, and L5-S1—are discussed in the individual chapters about these regions.)
3.3 (TOP LEFT) CERVICAL FACET JOINT ANGLE
3.4 (TOP MIDDLE) THORACIC FACET JOINT ANGLE
3.5 (ABOVE LEFT) LUMBAR FACET JOINT ANGLE
3.6 (RIGHT) ANTERIOR LONGITUDINAL LIGAMENT AND POSTERIOR LONGITUDINAL LIGAMENT, INCLUDING UNIQUE L5 AND S1 AREAS
CONNECTIVE TISSUE
The bodies of the vertebrae are held together by two ligaments and the intervertebral discs. The anterior longitudinal ligament (ALL) is a very strong ligament located on the anterior surface of the bodies of the vertebrae from C2 to the sacrum (Figure 3.6). In fact some consider it the strongest ligament in the body. It is thickest in the thoracic region. It prevents the vertebrae from moving forward. The ALL is stretched in back bending and loosened in forward bending.
The opposite ligament is the posterior longitudinal ligament (PLL), located inside the vertebral foramen and running from C2 to the sacrum (Figure 3.6). The longitudinal fibers of the PLS are more dense than those of the ALL. The PLL limits or is stretched taut on forward bending and is loose on back bending, the opposite of the ALL.
The bodies of the vertebrae are also held together by a special kind of connective tissue known as the intervertebral discs. In fact the twenty-three discs are the main connectors between the bodies of the vertebrae. There is no disc between the skull and C1 or between C1 and C2.
The disc is the most important structure for the preservation of the function of the vertebral column. A healthy and plump disc helps maintain the range of motion (ROM) at the adjacent vertebral segment. Plump discs also help to keep the bodies of the vertebrae an appropriate distance apart. This helps to maintain the space necessary to prevent any impingement on the spinal nerve from the vertebral body. When the disc is compressed, it allows the vertebrae to approximate, and this can contribute to pressure on a spinal nerve.
Discs are unique in each region of the column. The cervical discs are thicker anteriorly and are smaller than their cervical bodies. The thoracic discs have the same anterior to posterior measurements as the body but are more narrow. This particular structure contributes to the relative restriction of the upper thoracic compared to the lower thoracic spine. The lumbar discs are higher anteriorly, particularly L5, which contributes to the creation of the lumbo-sacral angle. In the lower lumbar, the lordosis is formed by the discs and by the shape of the bodies, while in the upper lumbar, the curve is due to the discs entirely.
The cartilage that covers the ends of the vertebral bodies is called the cartilage endplate. The endplates of two adjacent vertebral bodies are connected by fifteen to eighteen layers of fibers called Sharpes ligaments. The outer layers are more vertical, while the innermost layers are more horizontal. This layered structure increases the stability of the connection.
Whenever you rotate the column, these endplates approximate, or move together, thus compressing the intervertebral disc. A simple example of how this works is to observe what happens when you wring and twist a towel to remove excess water. As your turn the towel, your hands come closer together. This is basically what happens to the layers of the disc whenever you perform a twisting asana. Even though we suggest to our students the image of lengthening during twisting, an image I find helpful, it is important to remember that what is actually happening is that the vertebral bodies are approximating, and the discs are being compressed.
In the body, the discs are partially supported by the pressure created by the abdominal muscles and organs; this pressure helps to keep the discs in place.
Figure 3.7 shows the effects of movement on the discs. When you bend backward, the discs are pushed slightly forward. There is usually no problem with this movement, as it is away from the spinal nerve. The opposite is true in forward bending: when you flex the column, as in Paschimottanasana, your discs are pushed backward, in the direction of the spinal nerve. Thus forward bends and twists that compress the discs are not recommended for students suffering from an impingement of a spinal nerve. Besides the spinal nerve, the other painful structures in the vertebral column are the PLL and the facet joint.
The disc itself consists of circular ligaments called the annulus fibrosus. These circular rings are connected to the Sharpes ligaments. The center of the disc is composed of the nucleus pulposus, a semigelatinous substance that is the weight-bearing axis for all spinal movements. The nucleus pulposus has no direct blood supply after the third decade of life. Yet it is made up of 80 percent water. So what keeps the disc plump and full of water? Movement does it, by a process called imbibition.
Imbibition, from the verb “to imbibe or to drink,” is the word used to describe the action of the disc passively taking up fluid from the surrounding tissue. Movement is what causes the disc to take up fluids. By bending forward, bending backward, and twisting, pressure on one side of the disc causes the other side of the disc to take up fluids passively, which helps it stay plump and healthy. When you bend forward, the back part of the disc is opened and can take in fluids; when you bend backward, the opposite happens. When we are young, the nucleus is full and contacts both cartilage endplates. As we age, the disc dries out, and this can lead to problems. Asana is an effective way to move the column safely in all directions, thus helping to maintain the plumpness of the disc.
3.7 EFFECTS ON THE DISCS IN (TOP) BACK BENDING AND (BOTTOM) FORWARD BENDING
3.8 DISC PROTRUSION, DISC HERNIATION, AND DISC PROLAPSE OF THE NUCLEUS
Figure 3.8 illustrates disc protrusion, disc herniation, and disc prolapse of the nucleus. The first sign of problems with discs is called protrusion. In this case, the nucleus moves out of its center location into the annulus. At this point, the student will not feel any numbness or tingling but may feel a deep, dull ache. Protrusion tends to happen in active people between the ages of twenty-five and forty. Herniation is the pathology in which the nucleus pushes against the edge of the annulus. The student may have as many as twenty attacks over time. True prolapse of the nucleus occurs when the nucleus moves outside the outer rim of the annulus and presses on the spinal nerve. This usually occurs with a movement that combines flexion and rotation and causes a sharp pain, which subsides. At that point, the student requires care from a health professional who specializes in the care of ruptured discs. Bed rest or surgery may be required to alleviate the pain.
Yoga teachers should be very careful when a student experiences lower back pain; if the student complains of numbness, tingling, or radiating pain, or has problems with bowel and bladder control, send the person immediately to a health care professional. Yoga postures can be begun very slowly once the numbness becomes pain, as this means the nerve pressure is decreasing. Only very experienced teachers should attempt to work with these students.
The classic presentation of someone with a prolapsed disc is to stand with a deviation of the column to avoid the pain. If a student is deviating left to avoid right pain, for example, this means that the prolapse is lateral. If a student is deviating over the painful side, in this case deviating right over a right-sided lesion, then the prolapse is medial. This means that the prolapse is in the direction of the spinal cord, and very great care should be taken. Usually an anterior prolapse causes much less pain and problem because it is into the ALL, which is not particularly painful. The three structures in the vertebral column itself are the PLL, the facet joints, and the nerve roots.
Another cause of radiating pain is when the piriformis muscle in the hip, one of the rotators, presses on the sciatic nerve as it exits the pelvis. Look for more discussion of this in chapter 8.
Here is an example of amount of pressure on the L3-L4 disc of a 154-pound man:
▶ lying on back: 66 pounds
▶ standing: 154 pounds
▶ upright sitting without support: 220 pounds
▶ sitting and bending forward 20 degrees: 264 pounds
▶ bent-knee sit-up: 396 pounds
▶ lifting a 44-pound weight with lumbar in flexion and knees straight: 748 pounds
Note: Thirty percent of weight in all positions (except lying) is dissipated by the muscles of the thorax and abdomen.
There are five ligaments that join other structures of the vertebral column together, other than the bodies:
▶ the ligamentum flavum (flavum means “yellow”), and it joins adjacent laminae from C2 to the sacrum. It is stretched in forward bending and twisting. It is loose on back bending. It also helps the spine return from flexion. It exerts a constant pull on the capsule of the lumbar facet joints to prevent the capsule from being caught in the facet joint upon movement.
▶ the supraspinal ligament attaches the points of the spinous processes from C7 to the sacrum. It is stretched on forward bending and twists and slack on back bending (Figure 3.9).
▶ the ligamentum nuchae is the portion of the supraspinal ligament that runs from the occipital protuberance to the spinal process of C7. It is stretched on flexion, as in dropping the head for chin lock and in Salamba Sarvangasana and Halasana.
▶ the interspinal ligaments connect adjoining spinous processes and run more along the side of these processes, connecting one process to the next. They are stretched on both twists and forward bends.
▶ the intertransverse ligaments run between the transverse processes. These ligaments are stretched in twisting poses.
NERVES
The spinal cord is the neural extension of the medulla oblongata of the brain. It exits the skull through the foramen magnum, or great opening. As a baby develops inside its mother, the spinal cord fills all the vertebral foramen from C1 to L5. But as the vertebral column continues to grow, the cord does not, so in the adult the cord ends at the distal end of the L2 vertebrae. At the end of the spinal cord, the nerves branch into the cauda equina, or horse’s tail (Figure 3.10). This structure fills the lower vertebral canal.
There is a covering to the spinal cord called the meninges. This covering is divided into three layers: the outer is the toughest and thus is called the dura mater, which also forms a covering for the spinal cord, nerves, and the brain. The middle layer of the meninges is the arachnoid mater, so named because it resembles the filaments of a spider web. This layer gives some support to the spinal cord. Between the dura and arachnoid layers is the subdural space. The innermost layer adjacent to the spinal cord is the thin vascular pia mater, which is actually the outer layer of the spinal cord. The space between the arachnoid and pia mater is called the subarachnoid space; it contains cerebrospinal fluid, which cushions the brain and spinal cord.
3.9 LIGAMENT NUCHAE, SUPRASPINAL LIGAMENT, AND LIGAMENTUM FLAVA (ABOVE)
3.10 CAUDA EQUINA (RIGHT)
Nerves emerge on both sides, all along the spinal cord. The first spinal nerve exits between the skull and C1, the second spinal nerve exits between C1 and C2, and so forth. This means that there are eight spinal nerves but only seven vertebrae. The nerves, like the vertebrae, are numbered from the top down. So spinal nerve C4 exits the cord between C3 and C4. Then, beginning in the thoracic region, the nerves are named for the vertebral body just above them.
The spinal nerves have two divisions, the anterior and posterior roots. Each spinal nerve controls a certain part of the body (Figure 3.11). The anterior nerve root, sometimes called the ventral nerve root, controls the muscles as well as the glands and organs of that particular region. The posterior nerve root relays sensation, including pain, temperature, pressure, touch, and proprioception. (Proprioception is “position sense,” that is, the sense of knowing where your body is in space.) The area of the body controlled by one posterior, or dorsal, nerve root is called a dermatome (Figure 3.12). This is important to know because when the student complains of radiating pain, you will be able to make an educated guess if perhaps a nerve root is compressed and about which spinal nerve root might be involved.
The symptoms of nerve compression are tingling, pain, and numbness. The student may complain of these feelings in the arms down to the fingers or in the buttocks down to the feet. The farther the symptom is felt from the spinal nerve root, the more severe the nerve compression. Contrary to what may seem obvious, numbness is the worse sign. The job of the nerve is to carry impulses. When a person feels tingling, some pressure is beginning to interfere with the oxygen supply to the nerve; if this continues, the person will feel pain. If the compression continues, the person will then feel numbness. When the compression is relieved, the sensation will go from numbness to pain to tingling to no abnormal sensation. Thus pain is a better symptom than numbness and means that the compression is beginning to be relieved.
3.11 (ABOVE) SPINAL NERVE
3.12 (RIGHT) DERMATOMES
Perhaps you can remember the feeling of sitting on your foot and it going to sleep. First it tingles, then it hurts, then it feels numb. When it wakes up, first it hurts, then it tingles, then it feels normal. This is a sign that the nerve is now receiving the appropriate amount of oxygen. Remember, nerves have a very high metabolic rate that requires a continual oxygen (O2) supply, and they are exquisitely sensitive to the loss of it.
An example of temporary nerve compression is sometimes experienced by people with bulky and strong arms when they practice Salamba Sarvangasana, with their hands supporting the back. Students may complain of tingling, pins and needles, or even numbness in the hands. These symptoms could be occurring because the student is compressing the brachial nerves in the armpit as they exit the thorax. This is likely due to the tightness of the shoulder muscles.
If this occurs, recognize it as a neurological sign, a sign that a nerve is not receiving sufficient oxygen. Consider too that the nerve compression could be created in the cervical spine itself, by a disc pressing on the spinal nerve, or it could be created by compression on the nerve at any place along its path. My suggestion is that you assume the least problematic explanation for this condition, that is, that the compression is occurring somewhere else other than at the spinal nerve. However, if the problem persists, the student should consult a health practitioner.
To help your student, have him move his blanket setup to the wall and come up in Salamba Sarvangasana again, placing his hands on his back and keeping his feet on the wall for support. If the tingling returns, have him place his arms out to the side, so his armpits are totally open. In most cases the tingling will go away. This is because the nerves to the upper extremity pass through the armpit area on their way to innervate the upper extremities. When the student with tight or bulky shoulders presses his hands to the back, he can be compressing the nerves in his armpit and thus causing the tingling sensation. If taking his hands away from his back does not immediately give relief, ask the student to come out of the pose and refer him to a qualified health care professional for evaluation.
MUSCLES
There are numerous muscles on the posterior trunk. Many are muscles that connect the trunk to the upper extremity or muscles that connect the trunk to the pelvis. These muscles are discussed in the chapters 11 and 12.
At present, however, we will discuss the main extensor muscles specifically. These spinal muscles are a complicated overlapping group of muscles that act like a single muscle functionally to extend the column. We tend to refer to all the muscles that extend the column as the erector spinae. Technically, the erectors are only one of the three main parts of the muscles that extend the spinal column. The best way to understand these muscles is to study the illustrations (Figures 3.13, 3.15, and 3.17) and the charts (Figures 3.14, 3.16, and 3.18).
The intermediate layer of the extensor muscles of the back are the erector spinae muscles proper. They are a series of long muscles, lying medially to laterally, with overlapping origins and insertions. When they contract, they act as a group to extend the vertebral column. These muscles lie in the groove on the side of the vertebral column.
The iliocostalis, with thoracic and lumbar sections, is the most lateral of these muscles; the longissimus, with sections attaching to the skull, the cervical spine, and the thoracic spine, is slightly more medial. Finally, the spinalis, with a portion joining the skull, one joining in the cervical region, and one joining in the thoracic region, is the most medial. The semispinalis capitas is the final member of this group.
The deep layer of the extensor muscles of the back are the paravertebral transversospinalis, or the oblique group. Generally these muscles run from one transverse process to the spinous process of the vertebra above and span one to three vertebrae.
KINESIOLOGY
The vertebral column can be thought of as a connected chain of moving parts, what kinesiologists call a kinetic chain. One way to visualize this is to think of the facet joints of each side of the column as a little column of its own. This column of facet joints moves as a whole. When one section becomes hypomobile, another section becomes hypermobile to take up the slack of the segment that is not moving well.
Each segment of the spine has a certain rhythm of movement. Try this with your student. Ask her to get on hands and knees on a nonskid mat. Have her begin to move her spinal column upward into flexion by beginning at the base of the skull so her head drops, then vertebra by vertebra, lifting each spinous process one by one. Suggest that she lift each vertebra one by one in the thoracic area as well, and then finally in the lumbar area. Repeat this once, and then have her reverse this exercise, so she is lifting from the lumbar spinous processes one by one to C1. No doubt this is difficult to feel, but it will reveal where her spine is hypomobile, that is, where she does not move well. She can continue to do this daily as both an awareness and a mobilization technique.
3.13 SUPERFICIAL LAYER OF THE EXTENSOR MUSCLES OF THE BACK
3.14 SUPERFICIAL LAYER OF THE EXTENSOR MUSCLES OF THE BACK
3.15 INTERMEDIATE LAYER OF THE EXTENSOR MUSCLES OF THE BACK
3.16 INTERMEDIATE LAYER OF THE EXTENSOR MUSCLES OF THE BACK
3.17 DEEP LAYER OF THE EXTENSOR MUSCLES OF THE BACK
3.18 DEEP LAYER OF THE EXTENSOR MUSCLES OF THE BACK
The spinal column is designed for movement, but it is also designed for stability. This stability is created in part by structures in the column that resemble the legs of a tripod stool. These three structures are the intervertebral disc as one leg of the stool and each of the facet joints as the other two legs. When you stand with all the normal curves undisturbed, that is, in the anatomical position, the curves are in a neutral position, and all three legs of the stool are in contact. That is the position in which the spinal column is the most stable.
To demonstrate this, have your student stand in Tadasana on a nonskid mat. Once he is aligned and after asking permission to touch him, stand behind him and firmly press down on the tops of his shoulders. If he is aligned with a perfect tripod alignment, he will withstand your pressure with no problem. However, if there is a deviation, for example, his lumbar curve is in slight flexion or slight extension, he will buckle slightly under the pressure. This is one of the easiest ways to check for the neutral alignment of the column.
When students move into asana, they distort the curves and eliminate the tripod shape. Of course, it would be impossible to move at all unless one was able to partially or completely reverse the spinal curves, rotate, and bend in all directions. But when in vertical poses like Tadasana, and when sitting, creating the neutral curves will create the most stability.
Another important aspect of the kinesiology of the vertebral column is the ROM of each segment. The ROM of each vertebral segment is determined by the intervertebral discs. If the discs are plump and full, the movement at that segment will be normal. If not, movement can be limited. The direction of movement at any vertebral segment is determined, however, by the angle of the facet joints.
For example, the angle of the cervical facets is about 45 degrees. This allows for flexion and extension, side bending, and rotation. More details about the movements allowed are discussed in chapters 4, 5, 6, and 7, which deal in depth with each region of the spinal column.
The effect on the movement of the column as a whole varies with flexion and extension. In flexion, there is stress on the supraspinal ligaments, the interspinous ligaments, the ligamentum flavum, the capsule of the facet joint, the PLL, and finally on the posterior disc. In extension of the column, the stress occurs first on the ALL, then on the disc, on the joint, and finally on the spinous processes, if there is any impingement of the superior one on an inferior one.
EXPERIENTIAL ANATOMY
For Practicing
3.19 TADASANA, WITH THE HANDS ON THE PELVIS
Applied Practice: Finding the Neutral Position of Your Pelvis
Prop: 1 nonskid mat
Take Care: Press lightly but firmly.
THE PELVIS is the pot out of which the spinal column grows. If the pelvis is tilted, the column is affected. Whatever sitting position you find yourself in right now, just move your pelvis in any direction only an inch and you will notice a direct effect on the column. Try it a couple of times.
To find the neutral position of your pelvis, stand on your nonskid mat in Tadasana. Put your hands around the top of the pelvis, across the tops of the illia, so your thumb is in the back and your fingers come around to the front (Figure 3.19).
Imagine that the top ridge of your illia (which is the spine of the illia) is parallel to the floor. This will take a little practice because this is a curved surface, so take your time. Let your fingers feel the anterior superior iliac spine (ASIS) of the pelvis and your thumbs feel the posterior superior iliac spine (PSIS). When you think you have found the neutral position, your fingers and thumb will be about the same height from the floor. To test if this is truly the right position, press straight down hard. If your pelvis is in a neutral position, no movement will occur. If the position you selected is not the neutral one, then you will feel a movement under your hands. Please remember that this is an art as well as a concrete adjustment, so if you are unable to understand it the first time, don’t be discouraged. Try it several times, until you find the position in which your pelvis is neutral.
Another way to verify that your pelvis is in a neutral position is to feel for any tension in the abdomen wall between the ASIS and the symphysis pubis. If you are in neutral, this area will feel soft; if not, it will feel taut.
For Teaching
3.20 TADASANA, WITH PLUMB LINE
Applied Teaching: Practicing with Normal Curves in Tadasana
Prop: 1 nonskid mat
Take Care: Make sure your suggested adjustments do not create lower back discomfort for the student.
TEACHING STUDENTS to be aware of their normal spinal curves can help them, not only in asana but also in their daily life, as they sit at a desk, lift heavy packages, and stand in line.
The first concept to understand is a plumb line, which is a vertical line that you can visualize on your student’s lateral side (Figure 3.20). It passes through the external auditory meatus of the ear, the center of the shoulder joint, the hip joint, the center of the knee joint, and finally the lateral malleolus of the ankle.
To help the student find this vertical awareness, have her stand in Tadasana on a nonskid mat and against a corner. When she does so, she should touch the corner at the occiput, mid-thoracic spine, distal sacrum, and superior coccyx. This aid is a little inexact but is nonetheless a good beginning to awareness.
As you help your student align herself in Tadasana, look for these additional common misalignments in the pose:
▶ Feet: Most people stand with a least one of their feet turned out. Notice the student’s feet and ask her to stand in Tadasana with the outside borders of her feet parallel to the edges of her mat. Try pressing down on her shoulders with her feet in her normal position, and then follow it with pressing down with her feet parallel. Both of you will feel the difference in stability when the outside edges of her feet are parallel to the mat. This is because, in the aligned position of the feet, the tripod of the facet joints of the vertebral column is created, as well as the maximum congruence of the concave-convex surfaces of other weight-bearing joints, like the hip joints and knee joints.
▶ Knees: One of the things students do in Tadasana is to push back on their knees to the point of hyperextension of the joints. Check that your student has not done this and that the imaginary plumb line runs directly through her knee joint.
▶ Pelvis: This is critical to position correctly. After she has given you permission to touch, stand behind your student and place your hands on the top of the crest of her illia. If your hand is straight and flat, the highest portion of the crest of her illia will be parallel to the floor. With your middle finger, now feel her ASISs. Imagine these points as just touching a virtual flat plane or wall parallel to the student. If her pelvis is aligned, both of these points will be parallel with the plumb line.
▶ Scapulae: Make sure her scapulae are not winging out and are as vertical as possible. Most people carry their scapulae in a diagonal rather than a vertical line in relation to the vertebral column.
▶ Head: Stand at her side and make sure that the plumb line runs through the outer auditory meatus of her ear and that her eyes are slightly lower than the top of her ears.
You can ask your student to try Tadasana at a protruding corner of a wall, with the following parts of the body touching it: coccyx, mid-thoracic spine, and posterior midline skull. See if this aids his understanding of Tadasana and his neutral spinal curves.
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Tadasana is not only important for maintaining the health of the spine but also helps to keep the abdominal organs in place. When you stand with the normal curves intact, the organs rest on each other to form a visceral column. When the spinal curves are disturbed, the force of gravity is no longer transmitted through the organs in the most efficient way, which puts stress on them, particularly the bladder. For more information, consultUrogenital Manipulation by Jean-Pierre Barral (Seattle, WA: Eastland Press, 1993).