Back Injuries

Back Anatomy

The Bones

When you are born, your spine is made up of 33 individual bones called vertebrae. As you mature into adulthood, the lower portions of your spine fuse together, leaving you with 24 different vertebrae when you are fully done growing and developing.

The 24 vertebrae that make up your spine are separated into 5 different regions:

• Cervical vertebrae: 7 bones of your neck labeled C1-C7
• Thoracic vertebrae: 12 bones of your upper and middle back labeled T1-T12
• Lumbar vertebrae: 5 bones of your lower back labeled L1-L5
• Sacrum: a triangular bone made up of 5 fused vertebrae
• Coccyx: your tailbone made up of 4 fused vertebrae

Each vertebra of the spine connects with the vertebra above and the vertebra below to form a facet joint. Facet joints allow individual movements between the vertebrae of the spine. The combined movements of multiple vertebrae at multiple facet joints allow the entire spine to move as one unit.

Motions of the spine include:

• Flexion: bending your body forward to bring your chest closer to your thighs
• Extension: extending your body to bend backward
• Sidebending: bending your body to the side to the right and to the left
• Rotation: twisting your body to the right and to the left

These motions occur at the cervical, thoracic, and lumbar regions of the spine while very little movement occurs at the sacrum and coccyx.

In addition to forming joints with each other, the vertebrae also form joints with other bones of the body, including the skull, ribs, and pelvis.

Each vertebra contains several distinct features, which include:

• Body: a large, round surface that allows the vertebrae to stack neatly on top of each other with spinal discs located in between
• Vertebral foramen: a large hole located between the body and the other features of the vertebrae that forms the spinal canal when vertebrae are stacked on top of each other. The spinal cord runs up and down the length of the spine though the spinal canal.
• Spinous process: a pointy ridge that extends back from each vertebra, forming the bumps that you can feel along your spine
• Transverse processes: two pointy projections that extend out from the sides of each vertebra
• Laminae: connection points between the spinous and transverse processes
• Pedicles: connection points between the transverse processes and body
• Intervertebral foramina: small openings out from the right and left sides of vertebrae formed by the stacking of vertebrae on top of each other. Spinal nerve roots exit from the spinal cord through the intervertebral foramina at each spinal level from C1-L2.
• Facets (articular processes): projections of bone that extend upward and downward from the laminae and connect with the facets from the vertebrae above and below to form facet joints

The Spinal Cord and Nerves

Your spinal cord is the main communication system between your brain and the rest of your body. Your spinal cord exits from the base of your skull and travels down your spine through the spinal canal formed from the openings in the middle of your vertebrae.

At each level of your cervical, thoracic, and lumbar spine, a pair of nerve roots branches off from your spinal cord and exits your spine through intervertebral foramina, small openings at the sides of the vertebrae. Each pair of nerve roots is named according to their corresponding vertebrae. 

• The L1 nerve roots, for example, branch off from the spinal cord at the level of the L1 vertebra of the lumbar spine of your lower back. 
• The only exception is the C8 nerve roots, which are associated with the C7 vertebra along with the C7 nerve roots, as there is no C8 vertebra.

The spinal cord typically ends around the L2 vertebra. From here, the spinal cord forms the cauda equina, meaning “horse’s tail,” a ponytail-like bundle of nerves made up of nerve roots from L2 or L3 and below.

Bulging or herniated discs cause parts of your discs to move into the openings where the spinal cord and/or nerve roots sit. When this happens, the nerves can become compressed and cause symptoms like nerve pain, numbness, tingling, and muscle weakness. Traumatic injuries like falls, high impacts, and motor vehicle accidents can also cause significant damage to your spine, which can potentially injure your spinal cord and/or nerve roots.

The Cartilage

There are two types of cartilage in the spine:

1. Articular Cartilage: a slippery lining that covers the ends of the facets. Facets of one vertebra connect with the facets of the vertebrae above and below to form facet joints that allow the vertebrae to move. Articular cartilage helps decrease friction between the facets and allows the spine to move smoothly as one unit through the movement of multiple facet joints. Over time and with age, this cartilage can start to wear away and lead to arthritis
2. Spinal Discs: thick, round portions of tougher cartilage called spinal discs lay between the bodies of the vertebrae of the spine. Spinal discs help cushion the vertebrae and strengthen the ability of your spine to support your body weight and absorb shock. Each spinal disc is like a jelly doughnut, with a tougher outer ring (annulus fibrosus) and inner jelly-like substance (nucleus propulsus). When you have a herniated disc, the inner jelly-like substance of the disc breaks through and oozes out of the tougher outer layer.

The Ligaments

Ligaments are tough bands of connective tissue that connect bones together. The spine has three long, thick ligaments that run up and down the spine and connect the vertebrae together. These ligaments also provide stability and prevent the vertebrae from moving too much to avoid damaging the underlying spinal cord and nearby nerve roots. The three main ligaments of the spinal column include the::

• Anterior Longitudinal Ligament: prevents excessive backward bending of the spine
• Posterior Longitudinal Ligament: prevents excessive forward bending of the spine
• Ligamentum Flavum: prevents excessive forward bending of the spine

In addition to the three main ligaments of the spine, the vertebrae also contain multiple smaller ligaments that provide additional support. 

• The interspinous and supraspinous ligaments connect the vertebrae together through the spinous processes, the pointy ridges of the vertebrae that extend out from your spine. 
• The intertransverse ligaments connect the vertebrae together through the transverse processes, two bony projections that extend out from the sides of each vertebra. 

Over time with aging, ligaments of your spine can weaken and thicken, which can limit the movement of your spine and compress nearby nerves. Thickening of the ligamentum flavum, in particular, is associated with spinal stenosis and resulting nerve compression.

The Muscles & Tendons

Tendons are tough bands of connective tissue that connect muscles to bones. Because the spine remains relatively stable throughout the day and does not move as much as other joints like those of the arms and legs, tendonitis, or inflammation of a tendon from overuse, typically does not affect any of the tendons of the spinal muscles. 

The entire length of the spine is supported by three vertical columns of muscles collectively referred to as either the erector spinae, spinal erectors, or paraspinals, meaning “next to the spine.” These muscles support keeping your spine upright and control side bending and backward bending of your spine. 

The three paraspinal muscles consist of the:

• Spinalis: the innermost muscle layer
• Longissimus: the middle muscle layer
• Iliocostalis: the outermost muscle layer

The movement of each vertebra of your spine is also controlled by tiny muscles that connect one vertebra to another. These include the multifidi and rotatores, which both function to rotate the vertebrae. 

Most importantly, the abdominal muscles help stabilize your lower back (lumbar spine) and control movement of the vertebrae as well. The four abdominal, or “core” muscles, include the:

• Transversus abdominis: the deep core muscle that stabilizes your lower back (lumbar spine)
• Rectus abdominis: the outer abdominal muscle that bends your spine and body forward 
• The internal and external obliques: abdominal muscles on the sides of your body that help side bend, rotate, and bend your spine forward

Your lumbar spine, or lower back, is a commonly injured area often caused or worsened by core weakness, or decreased abdominal muscle strength. Strengthening your core muscles can help alleviate low back pain and prevent injuries from occurring by increasing the stability of your spine.

Common Causes of Back Pain

Back pain can result from an injury or chronic stress to any of the structures within or surrounding your spine. This includes damage or irritation to:

• Bones: Trauma to the spine can cause a vertebral fracture. With advanced stages of osteoarthritis, bone on bone friction causes damage to the facets, causing the joints of the spine to become stiff and painful. 
• Spinal Cord and Nerves: The spinal cord and branching spinal nerve roots can become damaged or irritated from injury to your spine or become compressed from factors like tight muscles and bulging or herniated discs. 
• Cartilage: Cartilage lines the ends of the facets of the vertebrae and can be worn down over time with osteoarthritis of the spine. The spinal discs are also forms of cartilage that can wear out over time and become damaged from lack of proper support from surrounding core muscles. Strenuous activities, especially heavy lifting while your spine is bent forward, significantly increases pressure within your spine and can lead to bulging or herniated discs. 
• Ligaments: Ligaments that support and hold the vertebrae together can become stressed with injury or wear out over time, causing spinal instability and contributing to spinal stenosis.
• Muscles: Muscles that support your spine can become stressed and strained from poor posture, sleeping in a bad position, motor vehicle accidents, or heavy lifting. 

Back Pain Symptoms

Back pain can vary in location, but most often affects the low back. Depending on the underlying cause of your back pain, your symptoms may affect just one area of your spine or may cause additional symptoms that travel into your legs. 

In addition to pain, you may also experience other symptoms, such as:

• Joint stiffness
• Muscle spasm
• Muscle weakness
• Numbness or tingling into your legs
• Burning, shooting, or pulling sensations down your legs
• Difficulty moving in and out of bed
• Inability to stand or sit for long periods of time
• Difficulty laying down

Comparing Back Injuries

The type of symptoms you experience as well as how your injury or symptoms occurred can help differentiate between different types of injuries and conditions.

Osteoarthritis/Degenerative Disc Disease (DDD)
Cause: Degradation of cartilage and underlying bone that occurs over time from wear-and-tear, with increased risk with age, increased weight, prior back injuries, poor spinal alignment, and core muscle weakness
Symptoms:
-Diffuse low back pain that develops gradually and worsens over time
-Back stiffness and decreased range of motion
-Swelling around the affected vertebrae
-Cracking or grinding sensations within the spine with movement
-The feeling of increased pressure within the vertebrae, especially with changes in temperature and pressure
 
Muscle Strain
Cause: Injury or irritation to the muscles of the low back from poor posture, sleeping in a bad position, motor vehicle accidents, or heavy lifting
Symptoms:
-Muscle pain in the low back
-Tenderness to the touch over the affected muscle
-Increased pain with stretching of the affected muscle
-Decreased back range of motion 
-Inability to move your back in certain ways due to pain
-Muscle weakness
 
Spinal Stenosis
Cause: Narrowing of the openings of the vertebrae, either the large opening in the middle of the vertebrae (central stenosis) or the smaller openings in the sides of the vertebrae (foraminal stenosis)
Symptoms:
-Low back pain
-Radiating pain into the legs
-Numbness and tingling into the legs
-Weakness in the legs
-Increased pain with extension of the spine and positions like walking, standing, and laying flat
-Decreased pain with flexion of the spine and positions like sitting and bending forward
-Muscle cramping in the legs
-Poor balance
 
Bulging or Herniated Disc
Cause: Movement of a disc out of its normal alignment between the vertebrae, resulting in part of a disc that sticks out of the back of the spine (disc bulge) or the breaking and oozing out of the inner disc material (disc herniation)
Symptoms:
-Low back pain
-Increased pain with bending the body forward
-Decreased pain with extension of the back
-Radiating pain into the legs
-Numbness and tingling into the legs
-Weakness in the legs
-Joint stiffness
 
Vertebral Compression Fracture
Cause: Trauma to the spine, including motor vehicle accidents, direct contact to the spine, or falls, or with repeated bending and twisting movements in people with osteoporosis (low bone density)
Symptoms:
-Sudden onset of low back pain
-Increased pain with sitting up, standing up, and bending forward
-Decreased pain with laying down
-Joint stiffness and limited spine range of motion
-Loss of height of the spine
 
Lumbar Myelopathy or Radiculopathy (Sciatica)
Cause: Compression of the spinal cord (myelopathy) or lumbar nerve roots (radiculopathy) from a bulging or herniated disc or tight muscles
Symptoms:
-Low back pain
-Radiating pain into the legs that is burning, shooting, or pulling
-Numbness and tingling into the legs
-Weakness in the legs
-Muscle cramping in the legs
 
Spondylolisthesis
Cause: Slippage of one vertebra out of alignment in relation to the vertebra below it, either too far forward (anterolisthesis) or too far backward (retrolisthesis), from a compression fracture or degeneration over time
Symptoms:
-Low back pain that worsens with physical activity
-Increased pain with standing or walking
-Increased pain with extension of the spine
-Tenderness to the touch over the lower back
-Numbness, tingling, or weakness traveling into the legs
 
Ankylosing Spondylitis
Cause: Inflammation of the spine from an autoimmune condition that causes the body to attack its own joints
Symptoms:
-Severe back pain and stiffness
-Pain, stiffness, and inflammation of other joints
-Increased pain with rest
-Decreased pain with exercise
-Increased pain at night
-Hunched forward posture
-Fatigue
-Loss of appetite and weight loss
 
Scoliosis
Cause: Abnormal curvature of the spine of unknown cause, often influenced by genetics
Symptoms:
-Uneven posture affecting the spine, shoulders, ribcage, and hips
-Middle and/or lower back pain
-Back muscle tightness and spasm
-Difficulty expanding the lungs and ribcage with breathing
 
Cauda Equina Syndrome
Cause: Compression of the lumbar and sacral nerve roots of the cauda equina, resulting from injuries, spinal stenosis, tumors, or infections
Symptoms:
-Low back pain
-Radiating pain into the legs
-Lower body muscle weakness
-Difficulty controlling bladder and bowel movements
-Decreased sensation in the genital and anal regions
-Sexual dysfunction
 
Spinal Infection or Tumor
Cause: An infection caused by a virus or bacteria or tumor resulting from abnormal extra growth of cells, either benign (non-harmful) or malignant (cancerous)
Symptoms:
-Deep, aching spine pain that does not improve with rest
-Fever, chills, and fatigue
-Weight loss and loss of appetite
-Radiating pain and/or weakness in the arms or legs
-Loss of sensation

How to Diagnose Back Pain

The first step in determining a diagnosis for the underlying cause of your back pain is through a comprehensive medical history. Your healthcare provider will ask you several questions about your back pain to help figure out how and why it began. Questions that can help aid in the diagnosis of your back pain include:

• Did the pain start all of the sudden (acute back pain) or did it gradually build over time (chronic back pain)?
  • If the pain started all of the sudden, what were you doing when the pain started?
  • If the pain has been increasing over time, how long have you been experiencing the pain and has it been getting worse over time?
• Where is the pain located? Is the pain specifically located at one spot or do you feel the pain travel into your legs?
• Does the pain limit your ability to move your body in different positions?
• Does your pain and/or other symptoms limit your ability to sit or stand for long periods of time?
• Is it painful to complete daily activities, such as bathing, getting dressed, preparing meals, and driving?
• Does your pain get worse with either forward bending or backward bending?
• Do you have any other symptoms (fever, swelling, pain in other areas, signs of infection, etc)?
• What type of routine activity or exercise do you do?
• Do you have any other medical conditions?

The second step in determining a diagnosis for the underlying cause of your back pain is a physical exam. A good physical exam combined with a thorough medical history can sometimes be enough to determine a diagnosis for your back pain without requiring diagnostic imaging like x-rays or MRIs. Symptoms of many back conditions overlap, however, so diagnostic imaging may be needed if your symptoms do not improve after several weeks of conservative treatments like rest, physical therapy, pain medications, and heat or ice.

Your healthcare provider will look and feel around your spine and examine your posture. During your physical exam, your healthcare provider will:

• Look for: swelling, redness, bruises
• Feel for: abnormal positioning of your spine, tenderness, stiffness
• Listen for: popping, cracking, or grinding sounds with spine movement

Labwork 

For many causes of back pain, bloodwork is typically not needed as many back conditions are mechanical in nature and result from physical stress or injury to muscles, ligaments, nerves, discs, cartilage, or bone. Some inflammatory autoimmune conditions that attack the joints, however, can cause pain, stiffness, and inflammation within your spine without an obvious cause of injury.

If your healthcare provider suspects that your back pain might be caused by a systemic condition such as rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis (PsA), or an infection based on your medical history and physical examination, you may have bloodwork taken to test for certain inflammatory markers associated with these conditions.

Comparing Imaging Modalities (XRay, CT, MRI, Ultrasound)

While a comprehensive medical history and physical exam may be enough to determine a diagnosis, diagnostic imaging methods are often used for traumatic injuries or chronic conditions to determine the extent of damage to your spine.These include

• X-Ray: a 2-dimensional imaging technique used to examine the bones (vertebrae) of your spine to check for arthritis, spinal stenosis (narrowing of the openings of the vertebrae), or broken bones
• MRI (Magnetic Resonance Imaging): a 3-dimensional imaging technique used to examine the nerves and soft tissues of your spine, including the muscles, tendons, ligaments, discs, and cartilage, for signs of inflammation and damage
• Ultrasound: an imaging technique used to check for fluid accumulation or changes to the structure of tendons and ligaments
• CT (Computed Tomography): an image produced by a series of x-rays taken at different angles to provide a more detailed image to check for broken bones, infections, and tumors

Back Injury Prevention

Preventing back injuries is crucial for maintaining a healthy spine that will support you through all of your physical demands and activities and decrease the risk of developing arthritis as you age. Several factors come into play when it comes to back injury prevention. These include:

• Limiting sedentary behavior and staying active and exercising regularly 
• Getting enough rest in between exercising to allow your body to recover and avoiding strenuous exercise, especially heavy lifting, when your back is hurting
• Warming up your muscles and joints before working out
• Correcting muscle imbalances, especially through strengthening your core and glute muscles, to support good spinal alignment and prevent increased stress at your low back
• Stretching tight muscles, especially your hip flexors and hamstrings, which can affect your spinal alignment, to allow your joints to move in an unrestricted range of motion 
• Gradually building up your exercise intensity, duration, and frequency to decrease the risk of overuse injuries
• Losing excess body weight to decrease added stress around your lower back
• Using good form (body mechanics) when lifting and moving heavy objects
• Attending physical therapy sessions for “pre-habilitation”