The Anatomy of Your Posture From the book, “The Other Side of Pregnancy,” by Dr. Trenton Scott.
As we saw back in Chapter 4, what we would call bad posture has the very real potential of creating back pain. Especially during pregnancy, you need to be cognizant of your posture and work hard to maintain proper body positioning at all times to minimize the stress and resultant discomfort on your spinal column.
Attaining good posture is a little more complex than your mom yelling, “Stand up straight!” whenever you slouch.
In the medical community, there are two widely recognized concepts of posture: the developmental concept of posture; and, the neurological model of posture.
THE DEVELOPMENTAL CONCEPT OF POSTURE
We’ll discuss the developmental concept of posture first. This concept notes that posture in an adult is related to three factors: 1) heredity, 2) disease, and 3) acquired habit.
Hereditary posture: This part of the concept indicates that people have a genetic posture that comes from their mom and dad. The truth is people come in all shapes and sizes. Look to mom and dad to see what your future looks like if you just continue with your posture as it is today. In my clinical experience, I have observed that you have either your mom’s or your dad’s spine, rarely a mixture of the two. I’m convinced that you can do something about improving your posture.
If someone is heavy or “big-boned” or exceptionally tall, for example, your body type will obviously impact your posture.
I have found with my patients that changing diet, exercise, and sleep patterns can actually improve a hereditary posture situation. To effect this change requires thoughtful, conscious effort.
Disease posture: People suffer from several posture-affecting diseases which are too many to list here, but include things like rheumatoid arthritis, ankylosing spondylitis, and pathological scoliosis, among others. Subluxated (non-moving) joints in a young child, if left untreated, can also affect posture long-term.
Acquired posture: This is the impact our environment has on your posture. Sometimes we mimic the posture of those we admire. Also, we all acquire postural changes due to work, relaxation, home furnishings, sports activities, recreation, culture, diet, and—for the female segment of the population—pregnancy. Our environment can be difficult to change. If you sit eight hours a day at a computer keyboard, your pregnant body is going to have an effect on your posture.
THE NEUROLOGICAL CONCEPT OF POSTURE
In order for you to fully understand what I’m going to be describing as the neurological concept of posture, I’m first going to have to give you a brief anatomy lesson. I’ll try to make it as painless as possible, but you may need a nap partway through.
First, here’s what your spinal column looks like:
The vertebral column has four basic curves:
- The cervical (neck) curvature is lordotic. That’s a medical term that means it bends concave to the posterior. Lordisus, from the Greek for “bent backward,” is a medical term used to describe an inward curvature of a portion of the vertebral column. Two segments of the vertebral column, both the cervical and lumbar, are normally lordotic, that is, they are set in a curve that has its convexity in front and concavity behind.
- The thoracic (mid-back) curvature is kyphotic or convex toward the back. Kyphosis, from the Greek for bent, is a rearward curvature of the spinal column.
- The lumbar (lower back) curvature is lordotic or concave to the posterior.
- The sacral (tail bone) curvature is convex to the posterior.
Those are the curves. Now, you’re probably wondering how a bony part of your body can change the shape of curves. The reason was presented in Appendix A: The spinal column is not solid bone but is made up of many vertebrae of different sizes. These individual irregular bones of your spinal column allow it to change its curvature.
The default mechanism of the neurologic concept of posture calls for the muscle tension along the vertical axis of the spine to be regulated by brain and sensory neurons.
Your body continually makes adjustments without you even thinking about it. The problem with being pregnant, though, is that the size, shape, and movement of the baby dictates that you may, in effect, need to manually override the system.
The process is initiated when the sensory neurons send proprioceptive impulses from the body’s peripheral nerves through the spinal column to inform the body of its relationship to the center of gravity.
Your body automatically senses where your center of gravity is. This becomes complicated with a pregnant woman, though, because your center of gravity is continually changing, not just month to month, but minute to minute and even hearbeat to heartbeat.
The spinal joints (explained in Appendix A) most responsible for the proprioception or feedback are found, ironically, in the spine where lower back pain is manifested.
When the message is received by your brain, it, in turn, sends impulses out to the ligaments, joint capsules, skin, viscera, and muscle attachments from your feet, knees, and hips to compensate for the change in your center of gravity.
The vestibular system controls balance. It is located in the inner ear and coordinates the compensating reflexes of the eyes and head. This automatic response mechanism is responsible for keeping your eyes level with the horizon. It also sends input to the central nervous system informing the body of the center of gravity.
Medically speaking, pressure variants, nociceptive sensations, movements, and touch sensations are sent to the central nervous system to the medulla which constantly and instantaneously sends back messages to the appropriate body parts controlling posture.
The constant change in spinal curvatures with shifting weight and a rapidly shifting center of gravity continually alters the proprioception of your spinal structure. While all of that is happening, the cortical (high brain) function must accept the input as “feeling normal.” Often, the result is an expectant mother who is complaining about “bad posture” and backache.