Spinal Anatomy: The Definitive Guide 
Imagine a life entirely stationary, without the ability to bend, twist, walk, or dance. Without a spine, this would be our reality. The spine is the most essential structure of the human body – our mobility and balance rely on it, and our organs could not function without it.
For as often as we must use it, most people don’t know exactly how the spine works or how many roles it plays in our overall wellness. Keeping the spine healthy is vital if you want to live a full, active life. The following Spine Anatomy Guide will help you understand how the spine works, why it’s so important, and what you can do to take care of it.
Table of Contents:
1. The Spine and Your Body: What’s It Do?
2. Spine Anatomy: What Are the Parts of the Spine?
3. The Core: The Spinal Cord
4. The Structure: Vertebrae
5. The Cushion: Intervertebral Discs
6. The Flexibility: Facet Joints
7. The Mobility: Ligaments and Muscle
8. The Network: Foramina and Nerves
9. How Vertebrae Connect to Your Body
10. The Cervical Spine
11. The Thoracic Spine
12. The Lumbar Spine
13. The Sacral Spine
14. The Coccyx: Why Humans Have a Tailbone
15. Why is Spine Health Important?
16. Tips for Spine Health
17. Chiropractic Care and the Spine
The Spine and Your Body: What’s It Do?
The spine runs from the base of the skull into the hips. It gives your body structure and support and allows you to remain upright. Your body’s range of motion, flexibility, and strength is all derived from the spine. However, the spine was designed to do much, much more.
The spinal column actually protects the spinal cord, which stems from the brain through a hole in the bottom of the skull. About 45 centimeters in length, the spinal cord is incredibly fragile. It is one-half of the central nervous system, which is responsible for almost all functions of the body and mind. The body shields the spinal cord from potential damage by protecting it with the armor of bone and muscle that is the spinal column.
So, while the spine does keep us stable, it also keeps the central nervous system safe. In turn, the spine is responsible for the safety and function of all of our internal organs as well as the digestive, respiratory, immune, and lymphatic systems.
Spine Anatomy: What Are the Parts of the Spine?
The spine is a complex web of bone, tissue, and nerve. It’s part of the musculoskeletal system – the bones, muscles, cartilage, joints, and other connective tissue that support and stabilize the body. Fortunately, we can break it down pretty simply. The spine gets its structure from vertebrae, small bones that stack on top of each other to allow for flexibility. Between each vertebra is an intervertebral disc, which adds further mobility to the spinal column and absorbs the shock from any harsh or repeated motions. Facet joints connect each vertebra to the bone above and below, with a layer of cartilage protecting the bone from wear and tear.
Ligaments and muscle bind these bones together to form the spinal column. The spinal cord runs through the center of the spinal canal, fitting snugly between the vertebrae. Likewise, foramina (openings) are present between every pair of vertebrae, allowing space for spinal nerve roots, communicating veins, and strengthening ligaments to take hold. We’ll get into each of these structures more in detail below.
The Core: The Spinal Cord
The central nervous system (CNS) controls most bodily functions, including emotion, thought, movement, and more. The spinal cord is one-half of the CNS, and the brain is the other. In its simplest form, the spinal cord is just an extension of the brain.
The spinal cord is composed of the same nerve cell bodies that make up the structure of the brain, known as gray matter. Due to their structural similarities, some reflex movements can occur via the spinal cord even without the participation of the brain. Much like the brain, the spinal cord is incredibly sensitive – so, just as the brain has the skull to protect it, the spinal cord has the spinal column.
The spinal cord is connected to a section of the brain called the brain stem and exits through the skull into the spinal canal. As cranial nerves exit the brain stem, nerve roots exit the spinal cord to both sides of the body. This means that the spinal cord can carry messages back and forth from the brain to the billions of nerves dispersed throughout the body.
The Structure: Vertebrae
Vertebrae bear a majority of the pressure placed on the spine. Like all bones, vertebrae have an outer shell and an inner material. The outer shell, called cortical bone, is hard and durable. The inner material is called cancellous bone, which is more soft and spongy. Having this structure prevents the bone from getting prematurely brittle and stiff, thus limiting mobility.
In the front, vertebrae feature a large, round portion of bone known as the vertebral body. In the back, a vertebra has a spiny, bony ring. The ring of the vertebrae consists of 5 small spindles, which all serve their own purpose in the spine:
- The laminae, covers the spinal cord or nerves
- The pedicle, connects the laminae to the vertebral body
- The spinous process, provides the point of attachment for muscles and ligaments
- Two transverse processes, attaches back muscles to the vertebrae
The Cushion: Intervertebral Discs
Intervertebral discs are soft, gel-like cushions that rest between each vertebral body. Flat and round, intervertebral discs act like shock absorbers by helping mitigate the pressure placed on the spine. Discs also prevent your bones from rubbing against each other to avoid tears and fractures.
Each disc is made of a strong, fibrous outer ring called the annulus and a soft, jelly-like center called the nucleus. The annulus is the most durable area of the disc and is responsible for keeping both the center intact and connecting each vertebra together. The softer nucleus is responsible for absorbing impact and pressure.
The nucleus has a very high water content, which is what allows it to absorb shock without crumbling. However, as we age, this water content incrementally decreases. Dehydration of the spinal disc can cause back pain, as the disc can no longer hold the weight of the body and can collapse, compressing nerves exiting the spinal canal. Likewise, excess pressure on the spine can cause a disc to tear, rupture, or herniate.
The Flexibility: Facet Joints
Just like other bones of the body, the vertebrae of the spine have joints to link them together and provide them with flexibility. In the spine, we refer to these as facet joints. There are two facet joints between each pair of vertebrae, one on each side. Looking like two bony knobs, they extend and overlap each other to form a joint between adjacent vertebra.
Facet joints are classified as synovial joints, which means that they allow movement between the bones they connect. Facet joints give the spine its flexibility. Because of this, the ends of the joints are covered in a thick layer of cartilage to allow each bone to glide against one another. The synovial fluid inside of the joint keeps the bones lubricated, keeping movement friction-free. Much like intervertebral discs, the synovial fluid and cartilage in the joints can decrease as we age, causing pain and stiffness.
The Mobility: Ligaments and Muscle
While the spine contains a variety of tissue, it is primarily tendons, ligaments, and muscle that bind together to form the spinal column. Each structure serves a different purpose:
- Tendons connect muscle to bone
- Ligaments connect bone to bone
- Muscles stabilize and mobilize the spine
The muscles next to the spine are called the paraspinal muscles. Their role is to allow mobility. Each of these small muscles control some part of the movement between the vertebrae and the rest of the skeleton.
Paraspinal muscles are classified as either extensors or flexors. Extensor muscles allow us to stand up and lift objects. They are attached to the back of the spine. Flexor muscles are located in the front and include the abdominal muscles. As per their name, flexor muscles allow us to flex, or bend forward, and are crucial for controlling the arch in the lower back, as well as allowing us to perform lifting movements.
The Network: Foramina and Nerves
The spinal cord branches off to form 31 pairs of nerve roots. These roots reach the rest of the body through small openings between the vertebrae, which we call foramina. The two nerve roots in each pair go in opposite directions when traveling through the foramina – one goes out through the left opening; the other goes through the right opening. These nerve roots allow nerve signals to travel to and from your brain to the rest of the body. Keeping these openings free of compression or damage is crucial in ensuring proper nerve flow.
Each set of nerves connects to specific parts of your body. This is why damage to the spinal cord can cause pain or paralysis in certain areas and not others – it all depends on which spinal nerves have been affected. For example, nerves in the lower back travel to the legs, pelvis, bowel, and bladder. Nerves in the upper back go to the arms and upper chest. Damage to the nerves themselves can cause pain, tingling, or numbness in the area where the nerve travels.
How Vertebrae Connect to Your Body
The individual vertebrae of the spine stack in such a way that they curve inward, then outward, and then back inward. When viewed from the side, a healthy spine has an S-curved shape. This allows for an even distribution of weight that helps the spine withstand daily stress. Doctors use the direction of each distinct curve to classify the spine into three segments.
The cervical spine is first. The cervical spine, or upper back, follows the first inward curve and runs from the base of the skull to the shoulders. We typically refer to the cervical spine as the neck. The thoracic spine, or mid-back, follows the outward curvature of the spine, forming a C-shape. It runs from the top of the shoulders to the bottom of the ribs. The lumbar spine, or lower back, follows the last inward curve of the spine. It runs from the bottom of the ribs down to the hips.
Each section of vertebrae reacts with individual body parts or bodily functions in a specific way. Much like how individual nerve pairs travel to specific locations in the body, the vertebra each pair exits from has related communication with the same body part. When vertebrae are injured or shifted from their respective place in the spine, they can compress nerve flow and interfere with communication from the brain to the body.
The Cervical Spine
The cervical spine consists of the first seven vertebrae of the spine. It begins just below the skull where the spinal cord exits the brain stem and ends at the top of the shoulders. The cervical spine is the most flexible section of the spine. This is so you’re able to turn your neck and head in a variety of angles and directions. The upper two vertebrae of the cervical spine allow for rotation thanks to their shape. They are called the atlas and the axis.
The atlas is the first cervical vertebra. Medically, we refer to this bone as C1 – the C standing for cervical, and 1 denoting that it is the first vertebra in the cervical spine. Each cervical vertebra below C1 follows the same naming convention: C2, C3, and so on until C7.
These vertebrae control the healthy function of:
- Base of the skull
- Neck muscles
8 Common Causes of Cervical Pain
While the cervical spine was designed for mobility, its limited muscle support makes it very susceptible to injury. Likewise, this section of the spine must support the weight of the head. Averaging 15 pounds for an adult, the head is a lot for the small, thin set of bones and limited tissue of the cervical spine to bear. Intense, sudden movements such as whiplash injuries pose a significant risk to the neck. Direct impact can cause damage to the ligaments, bones, nerves, or even arteries that carry blood to the brain.
Neck pain can have a variety of causes, but the most common injuries and disorders of the cervical spine include:
- Muscle strain
- Ligament sprain
- Herniated disc
- Pinched nerve
- Vertebral fracture
- Vertebral dislocation
- Spinal cord injury (SCI)
The Thoracic Spine
The thoracic spine begins directly below the cervical spine. It is made up of 12 vertebrae, which are numbered T1 through T12. These vertebrae connect to your ribs and are the foundation of the thorax – the area of the rib cage between the neck and the diaphragm.
Unlike the cervical spine, the vertebrae of the thoracic spine are not made for movement. They feature smaller, more narrow intervertebral discs and a smaller spinal canal for the spinal cord to pass through. For these reasons, the range of motion in the thoracic spine is minimal. However, the body benefits from this lack of movement, as the sturdiness of the thoracic spine serves as protection for the heart, lungs, and other internal organs.
The nerves located in the thoracic vertebrae branch off to numerous areas of the body, controlling communication to:
- Blood supply to the head and heart
- Heart/coronary arteries
- Bronchial tubes/lungs
- Small and large intestines
The vertebrae and nerves of the thoracic spine have a direct effect on nervous system function of the internal organs. When there is interference due to an injury or inflammation in the vertebra, the function of these organs can be impaired. This can result in stomach pain, constipation, bladder incontinence, fatigue, and more.
What Causes Thoracic Spine Pain?
The thoracic spine moves significantly less than the other segments of the spine, which generally makes it less susceptible to injury. However, this is not to say that the middle back suffers less.
Common injuries and disorders of the cervical spine include:
- Herniated disc
- Pinched nerve
- Vertebral fracture
- Muscle sprain or strain
- Spinal cord injury (SCI)
The Lumbar Spine
The lumbar spine is shaped like the letter C. If you think of the entire spine as having an S-shape, the lumbar spine is the bottom of the S that curves upward. There are five vertebrae in the lumbar spine, dubbed L1 through L5, with L1 immediately following the thoracic vertebrae. The vertebrae in this section are the largest in the entire spine. Likewise, the spinal canal here is larger than the rest of the spine to allow more space for nerves to travel freely.
The primary function of the lumbar spine is to bear the weight of the body. This is why vertebrae in the lower back are larger: they’re responsible for absorbing the stress of lifting and carrying heavy objects. The same can be said for the larger spinal canal. A plethora of nerves leave the foramina of the lumbar vertebrae, directly communicating with the various location in the lower body, including:
- Reproductive organs
- Large intestine
- Upper legs/thighs
10 Common Causes of Lower Back Pain
When people experience back pain, it often occurs in the lumbar spine. In fact, more than 80 percent of the population will experience low back pain at some point in their lifetime. This is because lumbar vertebrae are connected to the pelvis, which is where most body movement and weight bearing takes place.
The lumbar spine is where most people tend to place too much pressure, such as when carrying a heavy object, bending to lift something, or twisting to move an object. These actions can cause repetitive injuries which can damage the intervertebral discs, or compress the nerves flowing out of the lumbar vertebrae. Sciatica, the common condition that leads to burning, stabbing, or radiating pain in the legs and buttocks can be caused by nerve compression in the lumbar spine.
Other common causes of lumbar pain include:
- Herniated disc
- Collapsed disc
- Pinched nerve
- Muscle strain
- Ligament strain
- Degenerative disc disease
- Facet joint dysfunction
- Spinal stenosis
- Compression fracture
The Sacral Spine
The sacrum begins immediately after the lumbar spine at the top of the hip bones. Much like how the lumbar spine connects to the pelvis, the sacrum connects to the hip bones, known medically as the ilium. There are technically five sacral vertebrae which are fused together to form one structure. With the ilium, they form a ring called the pelvic girdle.
Where each hip bone meets the sacrum, there is a set of sacroiliac joints. Commonly referred to as SI joints, these joints are covered by two different types of cartilage. This is so that they can provide shock absorption for your spine while also providing a “self-locking” mechanism that stabilizes your walk. The SI joints lock on one side as weight is transferred from one leg to the other to keep you balanced.
In addition to keeping us mobile and balanced, the sacral spine is home to spinal nerves that communicate with the:
- Prostate gland
- Feet and toes
When nerve flow is interrupted at the site of the sacrum, or the SI joints become worn or inflamed, a variety of complications can develop. Leg cramps, digestive and bladder issues, swollen ankles, poor circulation, and of course, low back pain are all common when the sacrum is injured.
The Coccyx: Why Humans Have a Tailbone
It is a common old wives’ tale that the tailbone is where humans once had an actual tail. Unfortunately, the real reason for the tailbone is quite a bit less exciting. The tailbone is four small, fused bones that are medically known as the coccyx. As opposed to being the remnant of a tail, the purpose of the coccyx is to provide attachment for the ligaments and muscles of the pelvic floor.
Shaped like a small triangle, the coccyx is located at the very tip of the sacrum. In addition to providing stable anchorage points for ligaments and muscles, the tailbone is responsible for supporting our ability to walk upright and carry ourselves. Despite its small size, it can cause considerable pain when injured. Tailbone injuries are typically caused by high-impact sports, traumatic falls, or repetitive activities, such as cycling or rowing.
Symptoms of a tailbone injury include:
- Numbness when sitting
- Difficulty sitting from a standing position
- Inflammation and irritation
- Bruising and tenderness in the lower back
- Pain or strain using the bathroom
- Pain during intercourse
Why is Spine Health Important?
As the information highway of the body, an injury to the spine can literally impact the entire body. Therefore, keeping the spine healthy is paramount.
Without adequate nerve communication, your body wouldn’t know how to move, think, or even breathe. Without proper nerve function, your body literally could not survive. A healthy spine means that your spinal cord is safely protected and given enough room to send and receive nerve signals. So, while keeping your bones and teeth strong and healthy is one of the first things we’re taught as kids, spinal health should be the next item added to that list.
Judging by our Spine Anatomy Guide, you can see just how many aspects of the body hinge on communication from the spine. From motor skills and using the bathroom to organ health and respiratory abilities, the spine is responsible for keeping our bodies in order. A healthy spine equates to a healthy lifestyle. Not to mention, a healthy spine also means limited to no back pain.
6 Tips for a Healthy Spine
Keeping the spine healthy requires a lot more than remembering to bend from your knees when you lift something heavy. However, that doesn’t mean it needs to be complicated. A routine of healthy eating, stretching, and developing healthy habits can improve spinal health and keep your spinal column strong.
- Get a good night’s rest. Sleeping is a time for all of the structures in the spine to relax and repair. Therefore, your body requires a mattress and pillows that support your spine’s needs, as well as a sleeping position that won’t exacerbate any current injuries. Unsure of what sleeping position is best for you? Check out our blog “The Best Sleeping Position for Your Body According to a Chiropractor.”
- Wear shoes that can support your spine. Whether you’re walking for exercise or as part of your job, your shoes play an essential role in supporting your lower back. Did you know that poor footwear can throw your vertebrae out of alignment? Check out the effects of common footwear here.
- Practice good ergonomics. Office ergonomics measures how productive people are in the environment they’re given. However, both at the office and at home, ergonomics studies the way your body adapts to your surroundings. For example, how long are you sitting? Do you have proper posture while sitting? Do you have to contort your body to reach things or get comfortable? Proper posture and limited total sitting time can both benefit the spine.
- Exercise your core. Your spine is strengthened by the extensor and flexor muscles located in the abdomen and the middle back. These core muscles need to be strong to support the spine and take the pressure off your lower back. Check out these 5 exercises for a healthy back to strengthen and tone these muscles.
- Maintain a healthy diet. Having a core diet of vegetables, fruits, and lean meats is healthy all-around. However, one of the biggest problems that your spine can face is inflammation. So, keeping a diet of anti-inflammatory foods, as well as foods that keep your body hydrated, can really improve pain symptoms and overall spinal health. Take a look at these 10 foods that can improve back pain for inspiration.
- Enjoy the benefits of chiropractic and massage therapy. While your general practitioner might be your go-to for head colds or a stomach bug, no physician is as trained in matters of the spine quite like a chiropractor. So, when you have concerns about your spine or are trying to get your spinal health back on track, why go anywhere besides a chiropractor?
Chiropractic Care and the Spine
The foundation of chiropractic care is the diagnosis and treatment of mechanical disorders of the musculoskeletal system. Their practice is based in identifying and treating injuries to the body’s network of bones, joints, muscles, tendons, and other connective tissue. A chiropractor is a physician who is trained in both spinal structures and the central nervous system. As the two are so delicately intertwined, treating one cannot be done without addressing the other.
Chiropractors are not medical doctors, as they do not prescribe medications that will mask the symptoms of an underlying condition. Instead, a chiropractor utilizes a fully hands-on approach to treating an issue at its source.
Because each spine is unique, chiropractic care begins with a thorough physical examination, a study of medical history, and medical image testing when appropriate. Then, using specialized manual therapies, including spinal manipulation and manipulation of the joints and other soft tissues, a chiropractor works to ensure each element of the spinal anatomy is in its correct place in the body.
When each component of the spine is in place and inflammation-free, and nerves are free of compression, the body can initiate its natural sequence of healing.
Of course, while chiropractors are widely known for treating spinal health, they address all areas of the body, including the arms, legs, wrists, knees, and other areas. In addition to manual therapy, chiropractic therapy includes a variety of treatments, including:
- Cupping therapy
- Electrical stimulation (E-stim)
- Laser therapy
- Medical marijuana
- Physical therapy & rehabilitation
- Rapid release therapy (RRT)
- Therapeutic massage
- Ultrasound therapy
There’s much more to the spine than meets the eye. Before you reach for an over-the-counter medication to treat your current ailment, take a look at how chiropractic can help. Whether you’re suffering localized pain, headaches, digestive issues, or even allergies, the spine’s innate communication with the rest of the body can be your starting point to a healthier you. Get started with a chiropractor near you today.