Your spine gives your body shape and structure, supports your posture, allows you to move and experience sensation, carries messages between the brain and the body, and protects your spinal cord and the nerves within it. The spine is one of the most essential parts of the body. Without it, your organs could not function and you could not move or sense the rest of your body.
Here at Spine Muscles Nerves, we believe that patient education is essential for prevention and treatment. This post details the anatomy of the spine and anatomical causes of back pain. For those with back pain, this information will help you understand spinal anatomy and its relationship to the back pain you experience.
The Anatomical Parts of the Spine
The spinal anatomy consists of strong vertebrae (or bones), the spinal cord, flexible tendons and ligaments, many muscles, and numerous connected nerves. The entire spine is composed of these parts:
Spinal cord: The spinal canal holds a column of thirty-one pairs of nerves and millions of nerve fibers. This canal is called your spinal cord. The spinal cord goes from the skull and brain area to the low back. The spinal cord is the electrical wiring system between the brain and muscles and protected by the bony vertebrae.
Vertebrae: Thirty-three stacked vertebrae for the spinal cord. The cervical, thoracic, and lumbar spine are composed of distinct vertebrae that allow for movement. Conversely, the vertebrae at the base of the spine, the sacrum and coccyx, are fixed and immobile.
Facet joints: Facet joints are spinal joints that contain connective tissue that allows the vertebrae to move and slide against each other. The connective tissue is called cartilage. The cervical, thoracic, and lumbar facet joints act like hinges and allow you to move with flexibility in a variety of ways, such as twisting, turning, and bending.
Intervertebral disks: Spinal disks are flat cushions in between the vertebrae that contain a soft center and outer, flexible ring—much like a jelly doughnut. These round pillow-like structures absorb the spine’s pressure and shock. If under too much pressure, the inner gel-like center can squeeze out of place and hit nerves, causing pain and conditions like sciatica or intervertebral disk disease. When a disc herniates, it places pressure on nerve roots, which can cause excruciating pain that radiates into an arm or leg.
Neural foramen: The space between the vertebrae is called the neural foramen, which gives space for the nerve roots to travel between the spinal cord and the body.
Nerves: At every vertebrae level, there are nerve roots that branch off the spinal cord and out of the openings of the vertebrae. Nerves relay messages between the brain and muscles. Nerve impingements in the cervical area can cause pain to radiate into the shoulder and arm. Nerve impingements in the low back area can pain that radiates into the legs.
Ligaments and tendons: Ligaments that keep the spine in position connect the vertebrae. Tendons then connect from muscles to bone. Both tendons and muscles permit movement.
Back muscles: There are three categories of back muscles. They are the superficial (extrinsic) back muscles, the intermediate back muscles, and the intrinsic (deep) back muscles. Superficial muscles allow neck and shoulder movement. The intermediate muscles allow for breathing and thoracic cage movements. The intrinsic muscles are the deepest layers of the back muscles closest to your spine involved with motor control of specific body parts.
Typical Anatomical Causes of Back Pain Conditions
A variety of anatomical problems can occur in the spine. Most frequently, these types of problems can occur.
Sprains and strains: injury to muscles and ligaments of the back, often from overuse or an injury
Bone injuries and spinal fractures: fractures, chips, or cracks of the bones of the spinal vertebrae
Pinched nerve roots: compression of the nerves that go into the arms or legs
Irritated nerves: nerve irritation caused by inflammation or degeneration
Injured disc spaces: injury of the spaces between the vertebrae
Herniated discs: the compression and irritation of nerves caused by disc bulging or tears
Degenerative disc disease: breakdown of the joint spaces between the vertebrae in the spine
Osteoporosis: a bone disease that causes a loss of bone mass and density causing the weakening of the bones that may cause bone breakage
Osteoarthritis: a joint disease that is an inflammatory condition that causes cartilage in the joints to break down
Vertebral bone spurs: bony growths on the vertebrae of the spine
Ankylosing spondylitis: an inflammatory disease causing the bones in the spine to fuse and become inflexible
Spondylolisthesis: when vertebrae move out of place or out of alignment
Spinal stenosis: narrowing of the spinal canal making the spinal column too narrow for the spinal cord, causing pressure on the spinal nerves and spinal cord
Radiculopathy: when a nerve root in the neck is compressed or irritated. Cervical radiculopathy causes pain that radiates from the neck into the arm, chest, shoulders, and upper back. Lumbar radiculopathy causes pain that radiates down the leg and can cause numbness or tingling, muscle weakness, and/or decreased sensation.
Diseases and other conditions: tumors, cancer, fibromyalgia, kidney stones, endometriosis, osteomyelitis (a bone infection), rheumatoid arthritis, and more
The Segments of Spinal Anatomy
Your spine starts at your neck, goes down to your tailbone, and (if healthy) forms an S-shape. There are five distinct spine segments and thirty-three vertebrae in the spine.
Here is a description of the five different spinal segments:
Neck Area (Cervical Spine)
At the top of your spine are the seven C1-C7 cervical vertebrae. The cervical spine makes an inward C-shape. This is called a lordotic curve. These neck vertebrae allow you to move your head, including head nodding, tilting, and turning. Upper back pain occurs in this area.
The cervical spine is less prone to injury than the lumbar spine but more prone to injury than the thoracic spine or other areas of the spine that are fused together, as mentioned below.
Middle Back Area (Thoracic spine): Your middle back (chest area) houses your thoracic spine. The thoracic spine has 12 vertebrae, T1 to T12 that bends out slightly to make a backward C-shape. This is called a kyphotic curve. Middle back pain and back pain between shoulder blades occur in this area of the spine.
The thoracic vertebrae, and the ribs that attach to it, rotate very little. As a result, individuals rarely experience injuries or back pain in the thoracic vertebrae.
Low Back Area (Lumbar spine): Five vertebrae (L1 to L5) make up the lower part of your spine where low back pain can occur. Your lumbar spine connects to your pelvis, supports the cervical and thoracic parts of the spine, and carries most of your body’s weight. The lumbar spine bends inward in a C-shaped manner. This is called the lordotic curve.
The lumbar spine is most susceptible to injury because lifting and carrying stress this area and because the lumbar spine bears the most weight when during most common movements such as lifting, pulling, pushing, standing, bending, and sitting.
Sacrum: Below the lumbar spine area is a triangle-shaped bone called the sacrum. There are five sacral vertebrae (S1 to S5) that are fused together and do not move at all. The sacrum connects to your hips and, with the hip bone, they form your pelvis (otherwise known as the pelvic girdle).
Tailbone (Coccyx): Located at the bottom of your spine, the coccyx is a small, bony structure. Four fused vertebrae make up its structure. Your tailbone attaches to your pelvic floor ligaments and muscles.
Prevalence of Back Pain per Spinal Segment or Region
Most of us have experienced back pain in our lives. Back pain is prevalent, affects many individuals people globally, and is a large part of the current chronic pain crisis, detailed in our other blog post found here.
Back pain issues can affect any of the five major spinal areas highlighted earlier. Here are some current statistics about the prevalence of back pain in each of these five spinal regions.
Frequency of Upper Cervical Back Pain
Neck pain, sometimes called Cervicalgia, is a pain in or around your spine beneath your head. Neck pain is common. According to the National Center of Biotechnology Information (NCBI), 14-71% of adults in the United States experience neck pain at some point in their lives.
Prevalence of Thoracic Middle Back Pain
There is little motion of the thoracic area of the spine and, for this reason, there is little wear and tear or injury in this area. Thoracic back pain can occur in healthy individuals, but is more often due to serious spinal pathology than neck or low back pain. Worldwide, a significant portion of adults, ranging from 15% to 35%, experience thoracic back pain at some time in their lives, according to the National Council on Aging and recent research.
Lumbar Low Back Pain Frequency
The low back permits much more motion. It also carries the weight of the cervical and thoracic spine. For these reasons, the low back is much more prone to injury and back pain conditions. A significant portion of American adults, about 80%, will experience low back pain at some stage in their lives, according to NCBI. Find more information about the risk factors of lower back pain and tips for prevention in our blog post found here.
Statistics of Pain in the Sacrum
Pain in the sacrum is often called sacroiliac joint dysfunction. Inflammation of the sacroiliac joint (Sacroiliitis) can produce pelvic pain and stiffness. Research shows that between 15% and 30% of individuals in the United States who have low back pain concurrently experience pain in the sacrum.
Prevalence of Tailbone Pain
Tailbone pain is called coccydynia. This commonly manifests as pain confined to a particular spot. This pain worsens when sitting or with any activity that puts pressure on the very bottom part of the spine. According to the Cleveland Clinic, tailbone pain is common, though research findings show different statistics on the prevalence of tailbone pain.
Learning More Your Specific Back Pain Condition
There are several credible resources to learn about your specific type of back pain. To understand the anatomical causes of your back pain condition, some of the best information can come from your medical providers.
If you wonder about the causes of your particular back pain diagnosis, Dr. Gould and the clinical team at Spine Muscles Nerves are here to give you the information you need. We encourage you to raise questions during your office visits and to continue to read our Pain Management Blog to receive helpful information as you progress through your own prevention, treatment, and path to recovery.
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