Spinal Conditions & Anatomy
The spine is made of 33 individual bones (vertebra) stacked one on top of the other with 25 articulating joints. Ligaments and muscles connect the vertebrae together and keep them aligned. The spinal column provides the main support for your body, allowing you to stand upright, bend, and twist. Protected deep inside the vertebrae, the spinal cord connects your body to the brain, allowing movement of your arms and legs.
When viewed from the side, an adult spine has a natural S-shaped curve. The neck (cervical) and low back (lumbar) regions have a slight concave curve (Lordosis), and the thoracic and sacral regions have a gentle convex curve (Kyphosis). The curves work like a coiled spring to absorb shock, maintain balance, and allow range of motion throughout the spinal column.
- Cervical (neck)- the main function of the cervical spine is to support the weight of the head (about 10 pounds). The seven cervical vertebrae are numbered C1 to C7.
- Thoracic (mid back)– the main function of the thoracic spine is to hold the rib cage and protect the heart and lungs. The twelve thoracic vertebrae are numbered T1 to T12.
- Lumbar (low back)- the main function of the lumbar spine is to bear the weight of the body. The five lumbar vertebrae are numbered L1 to L5.
- Sacrum- the main function of the sacrum is to connect the spine to the hip bones (iliac). There are five sacral vertebrae, which are fused together.
- Coccyx region- the four fused bones of the coccyx or tailbone provide attachment for ligaments and muscles of the pelvic floor.
Getting an accurate diagnosis of the cause of back pain is critical, because different diagnoses will require very different treatment approaches. The sooner an accurate diagnosis is made, the sooner the patient can receive appropriate treatment for pain relief and to improve his or her ability to enjoy everyday activities.
Several tests may be used to diagnose a spinal condition, including a physical examination, neurological tests and imaging tests. A neurological exam will check your reflexes, muscle strength, walking ability, and ability to feel light touches, pinpricks or vibration. Imaging tests may include x-rays, CT scans, and MRI scans of multiple areas of the spine.
The most common fractures of the spine occur in the thoracic (mid back) and lumbar spine (low back) or at the connection of the two. These fractures are typically caused by high-velocity accidents, such as a car crash, fall from a height, or sports accident. However, spinal fractures are not always caused by trauma. People with osteoporosis, tumors, or other underlying conditions that weaken bone can fracture a vertebra during normal, daily activities. Spinal fractures are age dependent. In younger individuals fractures can occur in the low back due to spondylolysis and in the cervical spine due to a motor vehicle accident. Older individuals are more likely to encounter a lumbar compression fracture or cervical fracture.
The three major types of spine fracture patterns are flexion, extension, and rotation.
- Compression fracture- While the front of the vertebra breaks and loses height, the back part of it does not. This type of fracture is usually stable and rarely associated with neurologic problems.
- Axial burst fracture- The vertebra loses height on both the front and back sides. It is often caused by a fall from a height and landing on the feet.
- Flexion/distraction (Chance) fracture- The vertebra is literally pulled apart. This can happen in accidents such as a head-on car crash, in which the upper body is thrown forward while the pelvis is stabilized by a lap seat belt.
- Transverse process fracture- This fracture is uncommon and results from rotation or extreme sideways bending, and usually does not affect stability.
- Fracture-dislocation- This is an unstable injury involving bone and/or soft tissue in which a vertebra may move off an adjacent vertebra. These injuries frequently cause serious spinal cord compression.
The primary symptom of a spinal fracture is moderate to severe back pain that is made worse by movement. When the spinal cord is also involved, numbness, tingling, weakness, or bowel/bladder dysfunction may occur.
The bones (vertebrae) of the spinal column protect nerves that come out of the brain and travel down your back to form the spinal cord. Nerve roots are large nerves that branch out from the spinal cord and leave your spinal column between each vertebra. The spinal bones are separated by disks. These disks cushion the spinal column and put space between your vertebrae. The disks allow movement between the vertebrae, which lets you bend and reach.
With disc herniations, the disk may move out of place (herniate) or break open (rupture) from injury or strain. When this happens, there may be pressure on the spinal nerves. This can lead to pain, numbness, or weakness. The lower back (lumbar area) of the spine is the area most commonly affected by a slipped disk. Slipped disks occur more often in middle-aged and older men and women, usually after strenuous activity.
Symptoms of a slipped disk in your lower back may include sharp pain in one part of the leg, hip, or buttocks and numbness in other parts. You may also feel pain or numbness on the back of the calf or sole of the foot. The same leg may also feel weak.
Symptoms of a slipped disk in your neck may include pain when moving your neck, deep pain near or over the shoulder blade, or pain that moves to the upper arm, forearm, and fingers. You can also have numbness along your shoulder, elbow, forearm, and fingers.
Spinal stenosis is a narrowing of the open spaces within your spine, which can put pressure on your spinal cord and the nerves that travel through the spine. Spinal stenosis occurs most often in the neck and lower back.
Spinal stenosis is most commonly caused by wear-and-tear changes in the spine related to aging and occurs mostly in people older than 50 years of age. People with a spine injury, narrow spinal canal, or diseases such as arthritis and scoliosis are also at increased risk of developing spinal stenosis.
While some people have no signs or symptoms, spinal stenosis can cause:
- Pain in your neck or back
- Numbness, weakness, cramping, or pain in your arms or legs
- Pain going down the leg
- Foot problems
- Problems with bladder or bowel function
Spondylolisthesis is a condition in which one of the bones of the spine (vertebrae) slips out of place onto the vertebra below it. If it slips too much, the bone might press on a nerve, causing pain. Usually, the bones of the lower back are affected.
In children, spondylolisthesis usually occurs between the fifth bone in the lower back (lumbar vertebra) and the first bone in the sacrum (pelvis) area. It is often due to an injury or developmental disorder.
Bone disease and fractures can also cause spondylolisthesis. Certain sport activities, such as gymnastics, weight lifting, and football, put a great deal of stress on the bones in the lower back. They also require that the athlete constantly overstretch (hyperextend) the spine. This can lead to a stress fracture on one or both sides of the vertebra. A stress fracture can cause a spinal bone to become weak and shift out of place.
In adults, the most common cause is abnormal wear on the cartilage and bones, such as arthritis.
Symptoms of spondylolisthesis may include:
- Lower back pain
- Muscle tightness (tight hamstring muscle)
- Pain, numbness, or tingling in the thighs, buttocks, or feet
- Tenderness in the area of the vertebra that is out of place
- Weakness in the legs
A spinal tumor is an abnormal mass of tissue within or surrounding the spinal cord and/or spinal column. Spinal tumors can be benign (non-cancerous) or malignant (cancerous). Primary tumors originate in the spine or spinal cord, and metastatic or secondary tumors result from cancer spreading from another site to the spine. Tumors may spread to the spine from the breast, prostate, lung, and other areas.
Spinal tumors can occur inside the spinal cord (intramedullary), in the membranes (meninges) covering the spinal cord (extramedullary – intradural), or between the meninges and bones of the spine (extradural).
The symptoms of a spinal tumor depend on the location, type of tumor, and your general health. Tumors in the spinal cord usually cause symptoms, sometimes over large portions of the body, while tumors outside the spinal cord may grow for a long time before causing nerve damage. Symptoms of a spinal tumor may include abnormal sensations or loss of sensation, back pain, incontinence, muscle spasms, or muscle weakness.
Kyphosis is an exaggerated curving of the spine that causes a bowing or rounding of the back, which leads to a hunchback or slouching posture. The individual bones (vertebrae) that make up a healthy spine look like cylinders stacked in a column. Kyphosis occurs when the vertebrae in the upper back become more wedge-shaped. This deformity can be caused by a variety of problems, including:
Osteoporosis, disk degeneration, Scheuermann’s disease, birth defects, cancer and cancer treatments, spondylolisthesis, or a number of other syndromes such as Marfan syndrome or Prader-Willi disease.
An increased curve in the upper spine also can be caused by slouching. Called postural kyphosis, this condition doesn’t involve any deformities in the spine and is most common in teenagers.
In addition to an abnormally curved spine, kyphosis can also cause back pain, stiffness, difficulty breathing, and fatigue in some people. Mild cases of kyphosis may produce no noticeable signs or symptoms.
Scoliosis is a disorder in which there is a sideways curve of the spine, or backbone. Curves are often S-shaped or C-shaped. While scoliosis can be caused by conditions such as cerebral palsy and muscular dystrophy, the cause of most scoliosis is unknown. Scoliosis is most common in late childhood and the early teens, when children grow fastest.
Most cases of scoliosis are mild, but some children develop spine deformities that continue to get more severe as they grow. Severe scoliosis can be disabling. An especially severe spinal curve can reduce the amount of space within the chest, making it difficult for the lungs to function properly. Children who have mild scoliosis are monitored closely, usually with X-rays, to see if the curve is getting worse. In many cases, no treatment is necessary. Some children will need to wear a brace to stop the curve from worsening. Others may need surgery to keep the scoliosis from worsening and to straighten severe cases of scoliosis.
Signs and symptoms of scoliosis may include: uneven shoulders, one shoulder blade that appears more prominent than the other, uneven waist, or one hip higher than the other. Severe scoliosis may also cause the ribs on one side of the body to stick out farther than on the other side, back pain, and difficulty breathing.
The diagnosis and treatment of pediatric spinal disorders differs significantly from that of adult spinal disorders. A wide variety of congenital, developmental, traumatic and neoplastic disorders may occur in pediatric patients. Given the rapid growth that occurs in children, problems in the spine may become evident due to the development of scoliosis (abnormal curvature of the spine), pain, or neurological problems such as weakness or numbness. Unlike adult treatments, the surgical treatment of these disorders in children must take into account the expected growth and development of the spine.