THINK WITH YOUR WHOLE BODY.
—TAISEN DESHIMARU
ONE INTERESTING WAY to look at the posture of the cervical spine is to think of it as receiving the results of the posture of the spinal segments below it. If you slump, the neck will be affected; if you stand with your normal spinal curves in alignment, the neck will also be affected. However you choose to hold your lumbar and thoracic spines will create health or havoc for the cervical spine above them.
Head and neck posture can also signal your mood to the world. For example, you may communicate that you are feeling poised, assertive, meditative, or dejected, all by what you do with your head and neck. Poor neck posture can contribute to headaches, as well as to neck and eyestrain. Salamba Sirsasana and Salamba Sarvangasana, two of the core postures of yoga practice, depend on an awareness of and alignment in the cervical spine. Many of the problems associated with the cervical spine in asana can be avoided or solved by remembering to create and maintain a normal cervical lordosis as much as possible in each pose (Figures 4.1 and 4.2). This is the position of least strain for the neck.
BONES
The top two cervical vertebrae are especially unique, both in structure and function. The cervical spine originates at the juncture of the skull and the first cervical vertebrae, called the skull-C1 joint. The first cervical vertebra is also called the atlas, after Atlas in Greek mythology, who holds the world on his shoulders. Like him, we hold the globe of the skull on the atlas, C1. Another name for this joint is the atlanto-occipital joint (Figure 4.3).
The first cervical joint is notable because it is the only movable vertebra that has no body. Instead it is a bony ring with flattened facet surfaces that articulate with the corresponding surfaces on the distal skull to create the joint. The union of these two bones is shaped somewhat like a cup and saucer, the skull being the cup and C1 being the saucer. There is no intervertebral disc between the skull and C1. Also notable is that the first cervical vertebra has no spinous process.
4.1 (RIGHT) SAGITTAL VIEW OF THE CERVICAL SPINE
The second cervical vertebra is distinctive as well. During embryological development, the body of C1 migrates distally and joins the anterior body of C2 (also called the axis), creating a prominence called either the odontoid process or the dens. It is approximately ⅜ inch in height and protrudes upward into the C1 vertebrae. Like the skull and C1, there is no intervertebral disc between C1 and C2. The rest of the cervical vertebrae are more similar in construction. A unique aspect of the structure of the cervical spine is the bifid spinous process of C2 through C6. Another unusual aspect of the structure of the cervical spine is the existence of the transverse foramen. This is the opening in the transverse processes that allows for the passage of the vertebral artery, one of the two blood supplies to the brain.
It is important to understand the significance of this relationship in asana practice. The movement of the cervical spine can directly affect the blood supply to the brain. This artery can be occluded by a combination of rotation and extension. In other words, if you rotate to the right and backbend to the right you can occlude the right vertebral artery. For young people with healthy arteries, this movement is no problem. But in students over the age of sixty, it is important to pay attention to this movement. Especially pay attention to this alignment in seated twists.
Often a student will rotate the cervical spine in a seated twist, and you will notice that she tilts her head backward; be sure to suggest that she rotate her cervical spine while keeping her chin parallel to the floor instead. This will minimize any compression on the vertebral artery. Symptoms of vertebral artery compression can be dizziness and/ or a rapid back-and-forth eye movement called nystagmus.
The other source of blood and oxygen to the brain is the carotid arteries at the lateral sides of the neck. Take a moment now to find them. Turn your neck to the right about halfway. Palpate the contracted left sternocleidomastoid muscle near the jaw line. Now move your fingers slightly anteriorly, and feel the pulse of the carotid artery beneath them.
There is another bone in the cervical region: the U-shaped hyoid. It is located at the base of the tongue, at the level of the third cervical vertebra, below the mandible and above the larynx. It is the origin for the tongue muscles. The hyoid is unique in that it does not articulate with any other bone; rather it is held in place by the stylo-hyoid ligaments, suspended from the styloid processes of the temporal bones. It assists in swallowing and speech.
4.2 (OPPOSITE LEFT) POSTERIOR VIEW OF CERVICAL SPINE, WITH EIGHT CERVICAL NERVES EXITING AND VIEW OF THE VERTEBRAL ARTERY
4.3 (OPPOSITE RIGHT) ATLAS VERTEBRAE AND AXIS VERTEBRAE, WITH SKULL AND C1 LIGAMENTS
JOINTS
Only two movements are allowed at the skull-C1 joint: flexion and extension. These movements are determined by the angle of the facet joints, as they are at all vertebral segments. This relationship is like a cup and saucer. Thus the skull-C1 joint only allows for the skull to rock backward (extension) and forward (flexion) on C1. There is no rotation allowed at this segment.
The atlanto-axial joint, or C1-C2, on the other hand, allows for flexion, extension, and rotation because the facets face in an angle of about 45 degrees. This is also true for the rest of the cervical spine as well; we discuss it in detail later in this chapter.
CONNECTIVE TISSUE
In addition to the strong ligaments that hold the skull to C1, the strongest and largest ligament in the cervical region is the ligament nuchae (see Figure 3.9 in chapter 3). You can usually palpate this ligament easily along the central portion of the cervical spine in strong cervical flexion. With your neck in flexion, place your fingers against the spinous processes in the mid-cervical region. The ligament is usually prominent in this area.
You can feel this ligament while your student is in Salamba Sarvangasana. To do this, have your student practice with at least five blankets under his shoulders and with his feet on the wall. Once he is has rolled up into the pose, he can keep his feet on the wall for safety and support. After asking permission to touch him, feel the back of his neck, focusing on the mid-cervical region to feel the ligament. It should be slightly taut, as it is under a great deal of stretch.
In the cervical region, the posterior longitudinal ligament can fold into the spinal canal on extension of the cervical spine if the intervertebral discs have degenerated. (See Figure 3.6 for the location of healthy structures.) This can press on nerves, causing pain and dysfunction, so this action should be approached carefully by those with cervical disc degeneration.
4.4 SCHEMATIC OF THE CERVICAL PLEXUS
NERVES
As discussed in chapter 3, although there are only seven cervical vertebrae, there are eight cervical nerves, which are numbered in the same way as the vertebrae. C1 nerve exits the spinal column between the skull and C1 vertebra and is also called the suboccipital nerve. The second cervical nerve exits between C1 and C2 vertebrae, the third nerve between C2 and C3, and so forth (Figure 4.4).
This group of nerves is called the cervical plexus. It innervates spinal, neck, and upper trunk muscles, as well as the muscles of the face, throat, jaw, and diaphragm. In addition, divisions of the fifth to eighth cervical, together with the first thoracic nerve, form the brachial plexus, which controls the muscles of the upper extremity. This latter plexus is discussed in more detail in chapter 13.
MUSCLES
The muscles of the cervical spine can be divided into several regions and layers. These are the superficial, lateral cervical, suprahyoid, infrahyoid, anterior, and lateral vertebral.
The superficial muscle is the platysma muscle, a broad and flat muscle arising from the fascia of the pectoralis major and deltoid and inserting into the mandible and the muscles around the mouth (Figure 4.5). Contraction of the platysma causes the lower lip and corner of the mouth to move laterally and inferiorly.
The lateral cervical muscles are the trapezius (see chapter 13) and the sternocleidomastoid muscle (SCM) (Figure 4.6). The sternal head arises from the manubrium of the sternum; the clavicular head arises from the medial clavicle. Insertion is at the mastoid process. When contracted bilaterally, the SCM flexes the cervical spine. When contracted unilaterally, the SCM performs two actions: side bending to the same side and rotation to the opposite side.
4.5 SUPERFICIAL MUSCLES OF THE CERVICAL SPINE
4.6 LATERAL MUSCLES OF THE CERVICAL SPINE
This muscle can be clearly seen in Utthita Trikonasana. Notice your student’s neck when she is practicing to the right. Her right SCM will be seen to be quite prominent, as it is contracting strongly against gravity to turn her head to the left.
The anterior vertebral muscles are the next group and are presented in the accompanying illustration and chart (Figures 4.7 and 4.8). The lateral vertebral muscles are involved with breathing and are well known to yoga students (Figures 4.9 and 4.10). When all the scalene are fixed at their origins, as a group they lift the first two ribs and thus can aid in inspiration. When the insertion is fixed, the contraction of the scalenes unilaterally side bends the cervical spine.
The anterior neck is divided at the midline into anterior and posterior triangles. The hyoid bone divides the anterior triangle in half. The muscles of the hyoid area are the suprahyoid, stylo-hyoid, genio-hyoid, hyo-glossus, and the digastric. These muscles above the hyoid bone are involved in swallowing. The infrahyoid mucles are the infrahyoid, omo-hyoid, thyro-hyoid and sterno-thyroid. These muscles are involved in stabilizing the hyoid bone during swallowing and in making low- or high-pitched sounds.
The posterior triangle is between the trapezius and the SCM. It contains the semispinalis capitis, the levator scapulae, splenius capitis and the three scalenes.
KINESIOLOGY
A normal cervical curve is the position of least strain for all the cervical spinal structures. A healthy positioning of the cervical spine can be observed from the side in Tadasana. If your student is standing with all his spinal curves in neutral, his neck should receive the benefit of this alignment. Check this by observing the top of his ear. This should be slightly higher than the eye. In your mind, draw a line from the top of his ear to the top of the eye socket, and make sure he is carrying his head with his eye slightly dropped. Most people do not do this; they stand with the chin higher.
4.7 ANTERIOR MUSCLES OF THE CERVICAL SPINE
4.8 ANTERIOR MUSCLES OF THE CERVICAL SPINE
4.9 LATERAL MUSCLES OF THE CERVICAL SPINE
4.10 LATERAL MUSCLES OF THE CERVICAL SPINE
The opposite of this healthy head posture, actually carrying the head forward of the body in a forward head posture, can affect every bodily system, not just the neck itself (Figure 4.11). For example, when you hold your head in the forward head posture, you also slump and round your thoracic spine. This can interfere with breathing, digestion, and elimination. I have even heard the case of a woman who had tachycardia (rapid heart rate) because her head position was interfering with the vagal nerve and its control of the heart rate. Changing her head position resolved the problem. Teaching your students to carry the head over the body will no doubt contribute to their overall health.
As stated previously, the only movements allowed between the skull and C1 joint are flexion and extension. Thus this joint could be called the “yes joint” because its function is necessary in order for you to nod your head. But this nodding is very small.
You can experience this slight nodding when you perform the following. Sit or stand with your vertebral column in its normal curves. Pay special attention to the position of your head and neck. When you are satisfied that your cervical spine is in neutral, drop and then lift the chin about an inch or less. Repeat this movement back and forth, back and forth, flexion and extension. Try closing your eyes to concentrate more. Be sure that these movements are small. You will probably be able to feel the isolated movement at the skull and C1.
The next joint, C1-C2, allows flexion, extension, and rotation, in part because of the additional structure of the dens. Thus C1-C2 is called the “no joint” because it allows us to shake the head from side to side. In fact, the first 50 percent of rotation in the cervical spine comes from the C1-C2 joint. The additional cervical rotation is created by the remaining cervical joints, also called the lower cervicals.
This is important to understand. To feel this movement more clearly, lightly place the four fingers (not the thumb) of your right hand along the spinous processes of your cervical spine. Your little fingertip will be near your hairline and your index fingertip close to your shoulders.
Now slowly turn your head to the right. You will notice that about halfway into the rotation, the lower cervicals suddenly kick in and rotate to the left. This means the bodies of the cervical vertebrae are rotating to the right, what we call right rotation. Try it again with your left fingertips for left rotation.
This understanding will help you know what part of the cervical spine is dysfunctional if a student comes to class with the complaint that she can turn her head to one side about halfway and then it hurts or gets stuck. It will tell you that she has a misalignment in her lower cervicals. If, on the other hand, she cannot rotate her head to one side at all without pain or difficulty, then you know that the problem is with the C1-C2 joint.
Another important kinesiological point to understand about the cervical spine is the apex of extension and flexion in the lower cervical spine. Once again place your fingertips lightly on the spinous processes of your cervical spine; now extend your neck. Note where your feel the apex, or deepest point of the curve of the extension movement. Keep your fingertips there and perform flexion of the cervical spine. You will note that the apex of flexion moves down a vertebral level.
This is because the apex of extension is at C4, while the apex of flexion is one segment lower at C5. The apex is the point where the curve of the movement is the greatest. Thus the point of wear and tear for the cervical spine is at C4 for extension and C5 for flexion. If people have pain from cervical problems like herniated discs, they usually have it at the level of C4-C5.
4.11 (LEFT) NORMAL CERVICAL CURVE; (RIGHT) FORWARD HEAD, SAGITTAL VIEW
4.12 SIDE BENDING AND ROTATION, POSTERIOR VIEW
How the Neck Moves. One way to understand the movement of the spinal column is to visualize it as two long series of facet joints—one right, one left. In the cervical spine, these facet joints lie in the frontal plane, at an approximate angle of 45 degrees.
To get a sense of this, hold your hands in front of your face, palms facing you. Now tilt your fingers away from you so that your hands are in a 45-degree angle to the floor. With your hands in this position, it is easy to see how the facet joints could move forward and up, as well as down and back. The forward and up movement creates flexion of the cervical spine, and the down and back sliding of the facet joints creates extension. If on one side of the spine, for example, the facets on the right side of the spine move forward and up while those on the left move down and back, the result is a left rotation. Side bending is a special type of rotation.
The general rule of side bending and rotation for the cervical spine is this: in the cervical region, side bending and rotation occur to the same side, regardless of the position of the cervical spine at the beginning of the movement. For example, when you side bend to the left, the bodies of the vertebrae also rotate to the left. In other words, as the bodies rotate right, the spinous processes are pointing left (Figure 4.12).
You can feel this for yourself. Once again place your fingers lightly on your cervical spinous processes. Now side bend to the left; you will notice that your spinous processed rotate to the right. This means that the bodies have rotated left. While this may seem a little confusing at first, practice it for a few days and the principle will become clearer.
There is one exception to the law of side bending and rotation in the cervical spine. Notice this: when you side bend the neck to the right, we know your cervical bodies rotate right as well. But if this is true, then when you side bend right, why does your face still face forward? In other words, if the law is true, you would expect your face to turn down to the right. This does not happen and here’s why.
The law is true but there is an exception. It is this: the law is that side bending and rotation are to the same side in the cervical spine except for C1-C2, which rotates the opposite way. This accomplishes keeping the face forward during side bending.
Therefore if you have a problem with side bending right, the cause could be one of the following: a restriction of side bending right, a restriction of rotation right, or a restriction of rotation left of the atlas on the axis. It is worth the time to study these principles because understanding side bending and rotation will help you understand scoliosis, the lateral curvature of the vertebral column, which is discussed in detail in chapter 6.
The law of side bending and rotation is an attempt to describe the natural movements of the cervical spine. We can all override this law by purposely choosing another action. But it is likely that when we do, there may be discomfort.
Finally, a word about neck rolls. Many yoga teachers teach their students to roll their head and neck around in a circle, first one way and then the other, to stretch the neck. But this is a nonanatomical movement and is not recommended. Remember that the cervical facets are flattened surfaces that move either forward and up or down and back. The cervical joints are not ball-and-socket joints, like the hip joints or, to a lesser extent, like the shoulder joints. When you attempt to use the cervical spine as if it were a ball-and-socket joint, in a portion of the movement the joint is gapped to the side in a nonanatomical movement.
Instead of asking your students to do neck rolls, have them move the neck in one direction at a time. For example, ask them to rotate right and hold and breathe, then rotate a little more and breathe, and so on. It is fine to have them side bend with the same instructions. They can also turn the chin down toward one shoulder and then the other, as well as the more obvious movements of flexion and extension. But neck rolls are not indicated because of the structural shape of the cervical facets.
EXPERIENTIAL ANATOMY
For Practicing
4.13 UTTHITA TRIKONASANA
Applied Practice: Head Position in Utthita Trikonasana
Prop: 1 nonskid mat
Take Care: Do not try this if you have pre-existing cervical pain.
ALL LEVELS of students have experienced discomfort in the neck in Utthita Trikonasana at one time or another. The probable reason is that rotating the head upward in this pose does not follow the law of side bending and rotation. Thus it puts strain on the neck, as the added weight of gravity is added to the 20-pound weight of the head. When you are practicing this pose to the right, you are usually instructed to rotate your head to the left, or upward, and many students then notice discomfort, if not pain, at the base of the skull as they hold the rotation.
In the pose, you are initially side bending right, as shown previously in Figure 4.12. This is then slightly changed as you lift your head up a bit to keep it parallel to the floor. Now you are side bending left in the cervical spine, while practicing Utthita Trikonasana to the right (Figure 4.13). According to the law of side bending and rotation for the cervical spine, when you rotate right, you side bend right but C1-C2 turns the opposite way. Thus when rotating the cervical spine left in a right Utthita Trikonasana, you are overriding the rotation at C1-C2, which would ordinarily be to the right. Overcoming this natural tendency against the force of gravity can cause discomfort. If you have not felt this discomfort, then hold the pose longer and you will. Another suggestion is to practice the pose with the face forward, to minimize discomfort at the upper cervical region.
For Teaching
4.14 MARICHYASANA III
Applied Teaching 1: The Cervical Spine in Twists
Prop: 1 nonskid mat
Take Care: To protect the lower back, make sure that the student twists his pelvis with his whole spine in this pose and does not hold it stationary.
WHEN YOUR STUDENT practices a seated twist like Marichyasana III, notice his cervical spine from the back (Figure 4.14). As he twists to the right, the right side of the neck will shorten and the left will lengthen, according to the law. He is rotating right and thus is side bending right. If you measure carefully, the right side of his neck will indeed be shorter.
If the C1-C2 joint is functioning properly, his head will remain level because this joint rotates in the opposite way. If not, then you will notice that he is tilting his head back and to the right. This is a sign that there is a dysfunction at C1-C2.
4.15 SALAMBA SIRSASANA
Applied Teaching 2: The Cervical Spine in Salamba Sirsasana
Props: 1 nonskid mat • 1 blanket
Take Care: Your student should avoid this pose if she has pre-existing neck pain; numbness, tingling, or radiating pain in her arms; osteoporosis of the spine; high blood pressure; pressure in her eyes; or if she is menstruating, pregnant, or more than 25 pounds overweight.
WHEN THE STUDENT practices Salamba Sirsasana, observe her cervical spine from the side first (Figure 4.15). Notice if she is maintaining the normal cervical curve. Do this by making sure that the base of her skull is in a vertical line with her C7 vertebrae. Her chin should be level with the floor, not dropping or lifting. Notice if her neck looks too flat.
Now move to her back. There should be an even gully down the middle of her posterior neck. If the cervical curve is too flat, these gullies will not appear. If this is the case, she needs to move slowly toward her forehead so she creates the natural curve.
Applied Teaching 3: The Cervical Spine in Salamba Sarvangasana and Halasana
Props: 1 nonskid mat • 6 firm blankets, each folded into a shape of 12 x 21 x 28 inches
Take Care: Students should avoid this pose if they have pre-existing neck pain; numbness, tingling, or radiating pain in her arms; osteoporosis of the spine; high blood pressure; pressure in the eyes; or if they are menstruating, pregnant, or more than 25 pounds overweight.
4.16 SALAMBA SARVANGASANA
AS WE HAVE SEEN, the key to a healthy cervical spine is maintaining the normal cervical curve. This is virtually impossible to do while practicing Salamba Sarvangasana and Halasana. But protecting the cervical spine is important. If students stretch the soft tissues of the posterior cervical spine the maximum amount and then put the weight of the body on it, it can be not only challenging to the cervical spine but also potentially damaging.
To protect the cervical spine in Salamba Sarvangasana, I recommend placing firm blankets (folded as noted) under the shoulders to lift them at least 6 to 8 inches from the floor, so the cervical spine is at an angle of about 120 degrees (Figure 4.16). This is appropriate because there is only about 60 to 70 degrees of flexion allowed in the cervical spine normally. Any more of an angle than that would not only be forcing the cervical spine beyond its natural abilities but would also tend to recruit upper thoracic joints into too much flexion. The weight bearing of this pose is to be done on the shoulders and not on the cervical or thoracic spines.
Another way to ascertain if your student’s cervical spine is in too much flexion is to check the ligamentum nuchae. After asking permission, gently touch the back of your student’s neck while he is in Salamba Sarvangasana. Note how tight the ligament feels. If it is extremely tight and taut under your hands, he probably needs more height under his shoulders.
Halasana causes a strong flattening of the cervical spine, even more than Salamba Sarvangasana. Therefore, if the student already has a tight ligamentum nuchae in Salamba Sarvangasana, Halasana will cause additional strain to the structures of the cervical spine. Add even more height under his shoulders to protect his neck.
Applied Teaching 4: The Cervical Spine in Back Bends
Props: 1 chair • 2 nonskid mats • 1 blanket
Take Care: Do not practice this pose if there is pre-existing neck pain; radiating pain, numbness, or tingling in your arms; or lower back pain when practicing.
ONE OF THE MOST well-known back bends is Bhujangasana (Figure 4.17). Part of the pose involves extension of the cervical spine. But notice how some students practice this pose: they appear to back bend the neck, but really they are in cervical flexion, while back bending only the upper cervical spine.
4.17 BHUJANGASANA, LATERAL VIEW
To understand how this works, try this. While sitting, slightly flex your neck so that you are looking down. Now back bend from the top of your cervical spine only, by lifting your chin a few inches. Note how your lower cervicals are in flexion, while your upper cervical spine is in extension. This is not true extension, and it is common for students to do this in Bhujangasana.
To practice Bhujangasana, have your student lie on a nonskid mat, with a blanket on top for comfort (if desired) and another mat, folded in fours, placed under the abdomen. Position the legs about 12 inches apart, and internally rotate them. Place the hands on the floor, so the fingertips are under the tops of the shoulders. As the student exhales, she lifts up into an arch, primarily using the back to lift and minimizing the help from the arms. She should continue to breathe normally in the pose. Students can also practice this pose with their arms out to the sides (so the body forms a T-shape) or with the arms stretched back alongside the body and slightly lifted.
Make sure that students practice an even extension in this pose, by keeping the top of the head facing the opposite wall instead of stretching the chin outward.
LINK
During seated pranayama, students frequently include the practice of Jalandhara Bandha, or chin lock. In this position, the cervical spine is in full flexion. Please remember that the greatest reversal of the cervical curve occurs when the chin is tucked in first before flexion occurs. Make sure that when your students practice Jalandhara Bandha, they first flex the cervical spine and then draw the chin in to create the lock. This will lessen the stress on the cervical spine.