When it comes to the human body, there are many things that can be measured to be normal or abnormal. Vision, blood pressure, and body temperature are some of those things that have clearly defined normal limits that most people are familiar with. The structure of the human body can also be measured and normal versus abnormal values can be determined. In the picture below, normal structure is shown in regards to the appearance the outside of the body as well as the alignment of the spinal column.
From a front or back view, a person with normal structure will appear to be symmetrical--the head, shoulders, hips, and arms are even. There is no sign of a shift or rotation to either side. From this view, you should be able to draw a vertical line up from directly between the feet and see the bridge of the nose, the notch above the sternum, the navel, and the center of the pubic bone all be centered on this line. In addition, if you were to take an x-ray of someone with normal structure from the front or back, you will see the spinal column (made up of separate vertebrae and vertebral discs) centered on a similar line.
From the side view, in a normal structural alignment, there are some anatomical landmarks that should line up with a vertical line that starts at the lateral maleolus (the bump on the outside of your ankle). These points are the bump on the side of the hip (greater trochanter), the tip of the shoulder, and the hole in the ear. If you took an x-ray of someone with normal structure from the side, you will find that there is a neck curve that curves forwards, a mid back curve that curves backwards, and a low back curve that curves forwards.
When there is normal structure, the body is in an advantageous biomechanical state. However, when body shifts or rotates into an abnormal structural position, it can lead to a poor biomechanical state causing secondary conditions such as muscle tension, pain, numbness and tingling, fatigue, stiffness, headaches, and spinal degeneration.
