Understanding spinal pain has to be broken down into 3 different levels.

• On the receptor level

• On the tissue level

• On the individual or personal level

 
The Receptor level
The human body contains a wide variety of sensory receptors, each specialized to detect specific types of stimuli. These receptors can be broadly classified into several categories based on the type of stimulus they detect. Here’s an overview of the main types of receptors found in the body:

1. Mechanoreceptors - Detect mechanical forces such as pressure, touch, vibration, and stretch.

2. Proprioceptors - Provide information about body position and movement.

3. Nociceptors - Detect potentially harmful stimuli, leading to the perception of pain.

4. Thermoreceptors - Detect changes in temperature.

5. Chemoreceptors - Detect chemical changes in the environment.

6. Photoreceptors - Detect light, allowing vision.

7. Osmoreceptors - Detect changes in osmotic pressure (concentration of solutes in body fluids).

 
These receptors work together to provide the nervous system with comprehensive information about the body's internal and external environments, enabling appropriate responses to maintain homeostasis and interact effectively with the world.
 
For the purposes of understanding spinal pain, we are mainly concerned with nociceptors, proprioceptors and mechanoreceptors.
 
The Tissue level
Nociceptors are found in most tissues in the body to varying degrees. The density and distribution of nociceptors influence the sensitivity of different tissues to pain and the clinical presentation of pain syndromes.

• Skin – Very high density

• Joints and ligaments – High density

• Muscles and tendons – Moderate density

• Bone – Low to moderate density

• Intervertebral discs – Low density

• Nerve sheath – Low density

• Nerves – No Nociceptors.

 
The skin contains a very high density of nociceptors compared to other tissues. These nociceptors are specialized to detect noxious (painful) stimuli, including thermal (hot and cold), mechanical (pressure, cutting), and chemical (irritants) stimuli.
 
Joints, particularly the synovial membrane and ligaments, have a high number of nociceptors to detect mechanical stress, inflammation, and injury. Their pain is usually a sharp pain, particularly on movement of the region. However, the density is not as high as in the skin.
 
Muscles contain nociceptors that detect muscle damage, overuse, and ischemia (a shortage of blood). Muscle nociceptors are important for detecting deep, aching pain associated with muscle strain and injury. They  are sensitive to stretch, mechanical damage, and biochemical changes (such as the buildup of lactic acid), which can result in muscle pain or cramps. Their density is lower compared to the skin and joints.
 
Nociceptors in bone detect deep, aching pain often associated with bone fractures, infections, tumours, or diseases like osteoporosis.
 
Nociceptors in intervertebral discs detect mechanical stress, inflammation, dehydration and injury-related changes, contributing to discogenic pain when the disc is damaged, dehydrated or degenerated.
 
Understanding the distribution of nociceptors in these tissues helps explain the varying pain experiences associated with injuries or conditions affecting these areas. For instance, skin injuries typically result in sharp, immediate pain, whereas deep tissue injuries like those affecting bones or muscles often cause a more diffuse, aching pain.
 
Relationship between mechanoreception, proprioception and nociception.
 
Joints and ligaments, particularly spinal joints and ligaments, have a high density of mechanoreceptors and proprioceptors as well as nociceptors. Muscles and tendons also to a lesser degree. Studies have shown that when mechanoreceptors are activated by stretch or distortion, or where proprioceptors are depressed by restriction of movement, there is an increased activity of nociceptors, leading to pain.
 
In summary, increased mechanoreception or decreased proprioception can lead to increased nociception through mechanisms involving joint instability, abnormal movement patterns, muscle guarding, and central sensitization. Addressing proprioceptive deficits is crucial for preventing injuries and managing pain effectively.
 
General estimates based on epidemiological studies provide an idea of how common each cause might be. Here is a rough breakdown:
        ·  Mechanical Causes: 70-90%
        ·  Degenerative Causes: 10-15%
        ·  Traumatic Causes: 1-5%
        ·  Inflammatory Causes: 1-5%
        ·  Infectious Causes: <1%
        ·  Tumours: <1%
 
Mechanical causes are by far the most common cause of spinal pain.
They include Spinal joint fixation, ligament sprains, muscle strains, degenerated or herniated discs. More than one of these mechanical problems regularly occur together. For instance, spinal joint fixation can cause local ligament inflammation, local muscle spasm, and over time degeneration of discs.
 
Degenerative causes include Osteoarthritis (Degenerative Joint disease, bico de papagaio), disc degeneration and osteoporosis, a thinning and weakening of the body which makes a person more susceptible to bone fracture.
 
Traumatic causes include injury such as fracture or bruising from falls, accidents or contact sports.
 
Inflammatory causes include conditions such as rheumatoid arthritis, and ankylosing spondylitis which can affect the spine.
 
Infectious causes where infections such as osteomyelitis or discitis affect the spine or surrounding tissues.
 
Tumours where tumours affect the spine or surrounding tissues.
 
The individual level
 
Finally, spinal pain, when it happens also comes down to the individual.
Factors such as age, diet, and lifestyle influence greatly how resilient our body tissues are to the stresses we place upon them. Conditions such as obesity, dehydration, scoliosis, pregnancy can make the body more susceptible to pain or injury.
On top of that stressors in everyday life contribute to causing back pain.
 
Stressors may be physical, mental or chemical.
 
Common physical stressors include falls, accidents, contact sports, a sedentary lifestyle, poor postures (standing, sitting, working, sleeping), excessive work (physically or duration), poor sleep, extreme temperatures.
 
Common mental stressors include relationships, family problems, work deadlines, financial problems etc.
 
Common chemical stressors include poor diet, pollution, cosmetics, medications, smoking, alcohol, caffeine etc.
 
Every individual has a collection of stressors unique to them.
 
 
The chiropractic vs. medical approaches to spinal pain
 
Chiropractic philosophy recognises that spinal joint fixation is the primary cause of mechanical spinal symptoms, and that restoring correct spinal joint movement is the best form of treatment for alleviating spinal pain. Joint fixation can be the cause of inflammation, reflexive muscle spasm and ligamentous sprain, all capable of eliciting further pain.
 
The medical approach is to use medication in the form of painkillers, anti-inflammatory and muscle relaxant drugs to reduce the pain that is perceived. Unless infection is a factor, where antibiotics are required, the medication does not resolve the problem, rather masks the true cause, possibly allowing the problem to deteriorate undetected.
 
 
The importance of Proprioception
 
When people complain about back symptoms the two major symptoms that usually arise are pain and stiffness. Whilst most people focus only on pain (nociception) when it comes time to finally doing something about their back problems it is important to point out that proprioception plays an enormous part in our overall health and wellbeing. In neuroscience, proprioceptive input is considered one of the most critical types of sensory feedback for motor control. It is often emphasized that without proprioceptive input, the brain would struggle to execute precise and coordinated movements.
 
Diminished proprioception is often what prevents athletes from achieving their very best, and then later in life it makes elderly people less balanced and prone to falls.
 
Stiffness is the first sign that proprioception is being compromised, and usually commences well before pain shows up. Individuals may for months or even years put up with stiffness before pain starts.
And with stiffness comes degeneration. Studies (Videman 1987)1 have shown that within as little as 14 days, microscopic changes begin in the vicinity of a joint that has been immobilized. Over years, this becomes  osteoarthritis (Parrot beak degeneration).
 
So, to prevent chronic long-term spinal problems in our later years, one must maintain a healthy, flexible spine in our younger years. Whilst most people think it is “normal” to experience “a bit of stiffness” in our lives, it is not good, it is the first sign that degeneration is slowly happening. Early prevention and regular maintenance can stop the degenerative progress and prevent serious health issues in later life. Spinal maintenance is as important (some may even say more important) than maintaining your skin, teeth, fitness or any other body part that needs to be used.
 
​Stages of Spinal degeneration in the average “normal” individual without chiropractic intervention.
​
​
​
​
​
​
​
​
​
​
Please note: Degeneration is not caused by age, it is caused by how long a joint has failed to move properly.
 
Invest in your future. Get your spine, and those of your family checked today, to help prevent problems in the future.
 
For further information or to schedule a consultation at Advanced Spinal Care please contact the clinic on +351 914 105 094 via either phone, text or WhatsApp.
​
Information supplied by Chat CPT and Advanced Spinal Care.
 
1  Videman T: Experimental models of osteoarthritis: The role of immobilization – Journal of Clinical biomechanics, 1987:  2:223-229.