What you probably don’t know about the most important structure in your body…Spinal Anatomy 101

Every time you are in our office we are checking the function of your spine and nervous system. The nervous system is the master control system of the body that controls all function including respiration, digestion, elimination, immune function, growth, motor control and so much more. Chiropractic’s goal is to remove neurological interference to maximize the expression of your nervous system allowing your biological intelligence to be fully expressed throughout your life. So how do we determine all of this by feeling up and down your back? Well it all starts with the anatomy of the spine and nervous system, otherwise known as spinal anatomy.

The spine is made up of 33 individual bones stacked on top of one another. Of the 33 bones, 24 of them are actually moveable. Its main purpose is to:

  • 1) protect the spinal cord / nervous system from injury and 
  • 2) act as the main support of your body allowing you to stand upright, bend and twist. 

Spinal anatomy – The spine is broken down into 5 main sections: 

  • Cervical (neck) spine: 
    • This region of the spine helps to support the weight of the head on the body.
    • There are 7 bones total (C1 to C7). 
    • The upper cervical spine, the top two bones (atlas – C1 and axis – C2) has the greatest range of motion.
    • Without the special function of the joints at the top, you wouldn’t be able to nod your head yes or no. 
  • Thoracic (mid back) spine: 
    • There are 12 bones in this section and there are 12 sets of ribs that connect on each side of the 12 bones.
    • This area is important in protecting the vital organs such as your heart and lungs (like amour). 
  • Lumbar (low back) spine: 
    • There are 5 bones labelled L1 through L5. 
    • This area bears a large portion of the weight of the body and are much larger in size to absorb the stress of lifting or carrying heavy objects. 
  • Sacrum:  
    • This area is 5 bones that fuse together. 
    • It is how the spine connects to the hip bones (ilium) to form the pelvic girdle. 
  • Coccyx: 
    • The coccyx, often referred to as the tailbone is comprised of 4 bones that fuse together and is important for providing attachment for ligaments and muscles of the pelvic floor. 


There is a natural S-shaped curve to the spine when you look at it from the side. The neck and lumbar spine have a C-shaped curve normally (concave). The thoracic spine and sacrum/coccyx area both have a convex curve. 

The reason the curves are important are they work like a coiled spring to absorb shock, maintain balance and allow range of motion throughout the spinal column. 

Intervertebral disc: 

Each vertebra in your spine is separated and cushioned by an intervertebral disc which functions as a shock absorber and provides space for the nerve roots to exit out the side of the spinal column. 

When someone says they have been diagnosed with a disc herniation or a disc bulge, please understand this is the structure that would be directly affected. Many people have disc bulges on MRI studies but do not demonstrate any symptoms.

Facet joint: 

The facet joints of the spinal bones allow motion through the back. Each vertebra has four facet joints, one pair that connects to the vertebra above and one pair that connects to the vertebra below. 

As a Chiropractor, when a patient tells me they ‘injured their back’, ‘feel stuck’, ‘feel better leaning forward’ or ‘they just cannot stand up straight’, I will look to the facet joint to be a primary issue for this person. (Check out more about standing posture here)

Spinal cord: 

The spinal cord is 18 inches long and is the thickness of your thumb. It runs from your brainstem to the 1st lumbar vertebra protected by the spinal canal inside each vertebrae. At the end of the spinal cord, the cord separates into the cauda equina (latin for horse’s tail because that’s what all the nerves look like) and continue down through the spinal canal to your tailbone. These nerves become the same nerves that go into your legs and feet. (For more information about sciatic pain or pain shooting into you legs check out this blog). The spinal cord is the information super highway which relays messages between the brain and the body and vice versa. Any damage to the spinal cord can result in the loss of sensory and motor function below the level of the injury. 

Spinal nerves: 

From your spinal cord runs 31 pairs of spinal nerves or nerve branches. These nerves take the messages back and forth between your body and spinal cord to control movement and sensations. The spinal nerves go to specific areas and form a striped pattern as depicted in the image below. The areas of the skin the nerves travel to are called dermatomes and where the nerves go to the muscles are called myotomes. If there is interference to the nerve signals traveling to the skin or muscles we can identify this using sensory tests or motor tests. This pattern helps us to understand how some of the issues you may be facing can be related to the individual spinal nerves and vertebrae. For example, a loss of feeling or numbness and tingling in the middle three fingers may be cause by nerve interference in the spine at C6-C7.

The Nervous System

Not only does the nervous system control all the skin and muscles, it also controls and coordinations all organs and systems of the human body. As the nerves travel from the spine, they eventually end at an organ. Dr. Henry Windsor wanted to see if there was a connection between diseased organs and the structure of the spine. In 1921, at the University of Pennsylvania, he conducted 50 autopsies and published his results in the Medical Times. Dr. Windsor isolated a total 139 diseased organs. The diseased organs included the heart, lungs, stomach, liver, gallbladder, pancreas, spleen, kidney, prostate, bladder and uterus.

Following identification of the diseased organs, he then traced the corresponding nerves that supplied the organs back to the spine to see if there was any correlation. In 128, out of the 139 diseased organs, Dr. Windsor found minor curvatures and or misalignments in the spine. In the remaining 10 diseased organs he found misalignments at the spinal segments directly above and or below below the primary site. He concluded that if they included the cadavers with ‘faint curve and slight visceral pathology’ that the correlation was 139 out of 139, or 100%.

You have seen these nerve charts in our office. Based on the different coloured areas you can see which parts of the spine control which organs. The reason why the end organs can be affect by spinal malposition is not necessarily due to pinching of the nerve. Spinal misalignment causes irritation of the sympathetic plexus above and below the segment and causes vasomotor spasm affecting blood flow to the nerve and the end organ it supplies.

 

After reading this article you should have a basic understanding of the spine, its structure and the nervous system. If you have any questions about anatomy, how this may affect your health or someone you know please don’t hesitate to send us a message or email.

For more information, check out https://mayfieldclinic.com/pe-anatspine.htm