Spinal anatomy is a remarkably intricate structure of strong bones, flexible ligaments and tendons, extensive muscles, and a highly sensitive spinal cord and nerve roots. We often don't think about their form and function, though, until they become a source of pain.
The composition and function of the spine is a marvel of nature, providing us with a unique combination of:
- Protection for the spinal cord and nerve roots to safely relay messages to and from the brain and the rest of the body
- Shock absorption, accepting jolts and stress as we move about
- Flexibility, especially in the lower back and neck, allowing us to bend and twist in a full variety of movements
- Strength provided by the bones, discs, joints, and supportive muscles and connective tissues for upright posture and precision movements
Once back pain starts, such as with injuries or changes related to age, this intricate anatomical structure can be challenged, which sometimes leads to painful conditions. Here is what you need to know about the anatomical causes of pain that originate in your spine:
Lower back pain and sciatica
There are 5 vertebrae (bones) in the lumbar spine, labeled L1 down to L5. Because the lower back is relatively mobile yet carries the most load, it is the most likely area of the spine to wear down or sustain an injury.
Most episodes of lower back pain are caused by muscle strain. Even though this doesn't sound like a serious injury, the pain can be severe.
Most of the lumbar spine’s motion occurs in the lower spinal motion segments (L4-L5 and L5-S1), which are the spine’s two segments most likely to be a source of pain from conditions such as lumbar degenerative disc disease, a lumbar herniated disc1, or the facet joints.
A herniated disc or joint dysfunction in the lower back can also cause what is commonly referred to as sciatica. This is most commonly caused by irritation or pressure on the nerve roots as they exit the low back. These nerves eventually travel down the leg and serve to provide sensation and strength. The medical term for this is radiculopathy and symptoms will differ largely based on which nerve is affected on your back.
Neck pain and arm pain
The cervical spine (neck) supports the weight of your head and protects the nerve pathways that travel from your brain and spinal cord to the rest of the body. There are 7 vertebrae that run from the base of the skull down to the top of the thoracic (chest) region), labeled C1 to C7. The vertebrae at the top of the cervical spine are smaller and highly mobile, while the vertebrae at the base of the neck are larger.
Most episodes of acute neck pain are due to a muscle strain or ligament sprain. This type of injury is usually caused by overuse or overextension, such as when you sleep in an awkward position. It can also be caused by an injury or sudden force, such as from a whiplash injury.
If you have neck pain that lasts longer than a few weeks or months—or with predominant arm pain or neurological deficits in your arm or hand—an underlying anatomic condition is the likely cause, such as a cervical herniated disc, cervical spinal stenosis, cervical degenerative disc disease, or cervical osteoarthritis.
Upper back pain
The 12 vertebrae in the upper back, labeled T1 down to T12, comprise the thoracic spine. Each of the thoracic vertebrae are attached to the rib cage, providing a great deal of stability and structural support to protect the heart, lungs, and other important organs within the chest.
While the thoracic spine tends to be more rigid and resistant to injury compared to the lower back and neck, it is still possible for the upper back to become painful. Potential causes of upper back pain include muscles spasms, joint dysfunction, and thoracic herniated disc.
Knowing the basics of your spine will help you have a more meaningful discussion with your spine care provider in order to find pain relief. If you're more of a visual learner, try viewing related videos on this site about spinal conditions, anatomy, and treatments.