by Long Van, D.C.
Knowing your spine anatomy helps you understand how chiropractic works, especially when you hear your spine “crack,” while being adjusted.
The lay person’s term is backbone. We call it the spinal column. The spine is a solid yet adaptable multipurpose structure. It carries the weight of the head and torso, and allows us to stand, stretch, twist, bend, turn, dance, and play. The spine—all 33 bones of it stacked on top of each other—is our body’s structural foundation. That’s how the word “backbone” became a word to connote anything that means pillar or main support system.
Our spine or spinal column has five regions: cervical spine, thoracic spine, lumbar spine, sacrum, and coccyx.
An adult spine has a natural S-shaped curve when viewed from the side. The cervical (neck) and lumbar (low back) regions are slightly concave, while the thoracic and sacral regions are slightly convex. These curves allow your body to spring back, maintain balance, absorb shock, and move freely in many different directions in coordination.
The spinal column is composed of 33 bones stacked on top of each other. These 33 bones are the vertebrae, which are numbered and divided according to the five regions mentioned and illustrated above. The top 24 bones are movable; the vertebrae of the sacrum and coccyx are connected. Each region of the vertebrae in each region have their own unique reason for being.
Cervical (neck) region – This region is quite simply, the neck region, and is there to support your head, which is estimated to be about 10 pounds. There are seven (7) vertebrae in this region, and are numbered C1 to C7. C1 and C2 are the Yes and No vertebra. C1, the ring-shaped atlas, directly connects to the skull allowing for the nodding or Yes movement. C2, on the other hand, is the peg-shaped axis, which has a projection called the odontoid on which the atlas pivots around. This joint allows the No movement or the twisting movement of the head from left to right. Most neck problems are associated with poor posture, degenerative disc disease, osteoarthritis, whiplash and other neck injuries, pinched nerve, cervical spondylosis, and spinal stenosis.
Thoracic (mid back) region – The thoracic region or middle back holds the rib cage and protects the heart and lungs. Numbered T1 to T12, the 12 thoracic vertebrae allow for limited movement in this part of the body. The mid back region is very stable, but many of the mid back and upper back problems are caused by poor posture, muscle overuse, osteoarthritis, herniated disc, pinched nerve, and traumatic injuries from vehicular accidents or slip and falls.
Lumbar (low back) region– The lumbar region or lower back bears the weight of the entire body. It is there to help us lift and carry heavy objects. Numbered L1 to L5, the five lumbar vertebrae are much larger in size because they absorb the stress of lifting and carrying. This is the area associated with most back problems because it pretty much bears the brunt of all your body’s weight, movement, and their excesses, not to mention traumatic injuries caused by accidents.
Sacrum region – The sacrum connects the spine to the hip or iliac bones. There are five sacral vertebrae, which are fused together. Together with the iliac bones, they form a ring called the pelvic girdle. The sacrum is the support at the base of your spine and is the region that allows one to walk, jog, run, climb, dance, etc. It is so strong that it takes a severe fall to fracture it.
Coccyx region – Also known to us as the tailbone, the coccyx looks like a shortened tail at the bottom of the spine, and serves as an attachment site for tendons, ligaments, and muscles. It has been claimed that the coccyx serves no real purpose to human beings, but some say that it supports and stabilizes a person while in a sitting position.
Due to sedentary living, unhealthy lifestyles, and accidents, spines will develop abnormalities or injuries. Below are examples of the main types of spinal abnormalities that will help you understand where your spinal situation is at, and why your chiropractor is using a particular treatment to your body.
- “Sway back” or lordosis is an abnormal curve of the lumbar spine.
- “Hunchback” or kyphosis is an abnormal curve of the thoracic spine.
- Scoliosis is an abnormal curve from side-to-side.
The abdominal and back muscles aid in movement and keeping our spine aligned and the natural curves maintained. It is therefore imperative to keep our muscles well-exercised so that it may continually support our spine. For example, excess body weight can misalign a spine. Poor posture and lack of exercise weaken muscles, resulting in potential injury to the spine when there is not enough muscle strength to move the body in a particular direction or to help the body carry heavy objects.
Two muscle groups affect the spine: extensors and flexors. Extensors— located at the back of the spine—help us stand up and lift objects. Flexors— located in front and include the abdominal muscles help us flex, stretch, bend, and are vital in supporting the arch in the lower back.
The back muscles maintain the spine’s stability. As I wrote previously, weak muscles, being overweight, or even quite simply, having a big belly, can pull the spine out of its alignment, affecting the balance of the entire body. (see my article Exercises That Strengthen Back Muscles to Help with Back Pain).
Strong bones, flexible tendons and ligaments, and sensitive nerves also help keep the spine healthy.
“Anatomy of the Spine,” Mayfield Brain and Spine; last accessed 4/24/2019
“Neck Pain (Cervical Pain)” Medical Author: William C. Shiel Jr., MD, FACP, FACR / Medical Editor: Melissa Conrad Stöppler, MD, MedicineNet; last accessed 4/24/2019
“What are the most likely causes of upper back pain?” by Jon Johnson, Medical News Today; last accessed 4/24/2019
Spine Health, last accessed 4/24/2019
Spine Universe, last accessed 4/24/2019