Tag Archives: spine

Worship the normal curves

I learned a lot about the human spine this summer in the Experiential Anatomy online class led by the highly talented teaching team of Judith Hansen Lasater, Mary Richards and Lizzie Lasater. First of all, in fairness to Mary Richards, I need to get the nomenclature correct! As she noted, the vertebral column is a column or chain of vertebral bodies, whereas the spine is an anatomical term relating to a bony feature or ridge on various bones. Vertebra is singular; vertebrae is plural. There are some 33 bones in the vertebral column, most which move independently but several that are fused together and move as a unit.

The vertebral bones are arranged by size and shape, these being influenced by the curve in their respective part of the spine, and all of these attributes influences the function of that part of the spinal column. In order to bear more weight the bones get bigger from top to bottom of the column. In addition, the cervical vertebrae have less stability and more mobility, and progressing down the spinal column the lowest portion has more stability with less mobility.

Worship the normal curves 

is the mantra that began the study of the vertebral column, giving new meaning to the age old exhortation to sit (or stand) up straight. Years ago I was able to memorize the number of vertebrae in each area according to meal times: 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae (breakfast at 7, lunch at 12, dinner at 5). I guess the snack is the sacrum, with 5 vertebrae fused into 1 bone, and the coccyx (aka tailbone) that consists of anywhere between 3 to 5 vertebrae.

The cervical curve is the neck area, and has as its first two vertebrae C1, the Atlas (named for the Greek God who held the heavens on his head), and C2, the Axis, which is responsible for head turning. The thoracic curve’s 12 vertebrae all attach to two ribs each, one on either side. The lumbar, or low back vertebrae are the most massive of all the vertebrae; think about how much weight they must bear, hence the need for their size. As noted in a prior post, there is maximum pressure on the vertebral discs when sitting, medium when standing and the least amount of pressure when lying down. Turns out this is why we are a tad taller in the morning.

slinkyEver play with a slinky? If not, that’s a picture of one at the left. It is a spiraling column of wire that can “walk” down stairs and any movement in it reverberates throughout the entire slinky. This is similar to our backbone, which is a kinetic chain – “a connected chain of moving parts” where movement gets transferred up and down the spine.

The trio summed up the vertebral column as the central organizing axis – a giant, curved, coiled antenna receiving signals from the whole body. This axis connects to the hip axis, which is the central axis of movement. The part that connects these two axes is the sacrum, part of the vertebral column at the lumbrosacral joint (the joint between the last lumbar vertebra and the first sacral segment) and part of the pelvis at the sacroliliac joint (between the lowest part of the scarum and the iliac bone in the pelvis.)

My next post will explore each part of the vertebral column in a bit more detail.

Plums & Discs, Plumb Lines & Posture

A really juicy plum is sweet and full. Prod it with your fingers (palpating it!) and you can  feel the give-and-take within the body of the fruit. With that image in mind, imagine your plumvertebral column, the curvy, almost “slinky-like” chain beginning at the base of the skull and continuing down to your pelvis where the lumbar spine meets the sacrum.

The vertebral column is made up of vertebral bodies, and between each vertebral body is an intervertebral disc (IVD). Think back to that juicy plum, the give-and-take as you gently prod it. The IVD works in a similar fashion by providing cushioning to the vertebrae and acting as a shock absorber. During the day the intervertebral discs  sustain the pushing and prodding of the spine as it moves in all directions. As a result of gravity, by day’s end the IVDs have become compressed. There is maximum pressure on the discs when sitting, medium when standing, and the least amount of pressure when lying down. Indeed, after a sound night’s sleep you are a tad taller in the morning because the intervertebral discs have become plump with water and are less compressed.

As for that sweet juicy plum, once you have bitten into it the plum no longer responds the way it did beforehand. Perhaps the flesh of the fruit comes spilling out via drips and small chunks, and maybe you even round your back, jutting your head forward so the yummy mess doesn’t wind up on the front of your shirt! While puncturing the plum is good for your palette, this equivalent action in an intervertebral disc would be counter productive for your spine. Protruded, herniated or prolapsed discs occur when the nucleus of the disc breaks through the area surrounding it, much like your bite into the plum lets the center break through the area surrounding it.

PLUMB LINE (or What are the normal curves of the vertebral column?)
Place a book on your head and try walking without having the book fall off. The walking rhythm with the book staying put is the neutral position of your head in relation to the vertebral column.

To sit or stand with your vertebral column in its normal curvature you first need a sense of what that is within your body. In construction a plumb line is used to determine that something is vertical. In the body a plumb line is a vertical line that you can visualize on the outer side of the body. “It passes through the external auditory meatus of the ear (outer ear), the center of the shoulder joint, the hip joint, the center of the knee joint, and finally the lateral malleolus of the ankle (outer side of the ankle joint).” (From the online course Experiential Anatomy.) The plumb line touches upon body parts that, if vertically aligned, give rise to the normal curvature of the spine.

To find your plumb line ask someone to take a look at you from the side. Stand with your eyes slightly lower than the top of your ears, relax your shoulders, arms loose at your sides, feet and legs supporting your body. If you tend to tuck your tailbone, untuck it. According to Judith Hansen Lasater and Mary Richards in Experiential Anatomy, tucking the tail takes the body out of joint and inhibits the functional muscle patterns that support the core.

Ask your plumb line assistant to tell you what they see. If they note that your head is forward of the plumb line, and if this is not due to a structural issue, it is likely that the jutting of the head is due to sitting with a rounded back. Why might someone have a rounded back while seated? Think: driving, sitting hunched over a computer, looking down at a cell phone…

Sitting with a rounded back impacts the cervical spine and produces a forward jutting head (the head comes forward of the plumb line). When this happens, the weight is no longer being efficiently borne through the vertebral bodies. The result is flexion in the lower cervical (lower part of the neck) and back bending in the upper cervical, neither of which is beneficial to the spine.

POSTURE (adapted from Experiential Anatomy)
Come to your normal standing position. If you feel comfortable, close your eyes a moment and sense your body in vertical space. Reach the crown of your head towards the sky. Sense your normal curves within your vertebral column. If your eyes are closed, open them. These curves are what bear the weight of your body as it responds to gravity. Has anyone ever asked you to “sit up straight” or “stand up straight”? Physiologically it is impossible to straighten your spine because it just isn’t built that way; it is curved, not straight. The only “straight line” in the vertebral column is the line of force – the way gravity is carried through the column.

seated postureNow find a chair and sit on it. Not sure of the way to sit for optimal posture? The key to sitting is all in the pelvis! Once seated, roll slightly forward onto the pubic bone, feet comfortable on the floor or on a small stool if the chair seat is too high. The pelvis should be elevated above the level of the thigh bones, creating an approximately 120° angle between the torso and the thighs. (Not only did I learn this in Experiential Anatomy but also from Mary Bond’s Google Talk: The New Rules of Posture: How to Sit, Stand and Walk in the Modern World, where she suggests perching rather than sitting.)

To enjoy your posture as much as you (perhaps) enjoy your plums, work on keeping your posture in synch with your plumb lines, honoring your pelvis (pubic bone tilts forward in sitting, tail bone untucked in standing). And maybe take a yoga class!