Chiropractic Neurology deals with paying attention to the central and peripheral nervous system of the patient during the examination. It is important to determine the patients fatiguability of their nervous system during the initial examination. A person who has other health problems that are affecting their general health or certain medications a patient may be taking can create a fatiguability in the nervous system. A long standing subluxation complex can also fatigue the neural elements at the level of the subluxation. This is important because if we do not determine the level of fatiguability, the over stimulation to those structures through the spinal manipulation may exceed the metabolic rate of the primary neuron and can cause problems rather than helping them. The subluxation is still the main focus but the correction of the subluxation depends upon the proper analysis of the patient in what their neurological controls are doing at the time. As an example, a patient may come in with pain in the right hip. In the process of the examination you find that they also have antigravity motor weakness on the entire right side. It is more prudent to make the proper correction from the left side even though the symptomatology appears on the right due to the contra lateral central nervous system controls.

Excerpt of paper by Frederick R. Carrick, DC,PhD,DACAN,DABCN,DACNB,DAAPM,FACCN; 1998

When you manipulate a joint, any joint, but especially zygopaphyseal joints: you will evoke from within those joint capsules a certain population of receptor afferents by compression of their corpuscular endings. These afferents have a variety of effects in the human nervous system which effect the amount of pain, different primary perceptual experiences, the integrity of the motor system, as well as the function of autonomic nervous system for the integrity of life itself.

So, since biomechanical integrity will give us the highest population of receptor afferents, it is a very simplistic realization to understand that a decrease in biomechanical integrity or aberrant biomechanical relationships will have very high probability of decreasing the population of receptor afferents with a quantitative pathology or aberrations in the modalities to alleviate pain, to appreciate primary perceptual experiences, to be able to move and do the things we want to do, as well as to control our vital functions. So, what we have to do when we look at pain, is realize the modality of pain can not be isolated from the aspect of humanism; which is, in reality, you will find, is really a mechanoreceptor type of function which is preserved by Chiropractors.

Excerpt from:
Sensory Innervation of the Spinal Joint and Effects of Manipulation
The Chiropractic Neurological Examination by Joseph S. Ferezy, DC; University Chiropractic Consultants; Minneapolis, Minnesota; 1992

Type I Mechanoreceptors

Type I mechanoreceptors are located in the outer layers of the spinal joint capsule. When stimulated, they fire at a frequency proportional to the degree of any active or passive joint movement or traction. The firing rate is inhibited by joint end approximation. They have a low threshold and are therefore very sensitive to movement. They are termed dynamic receptors because they only fire with movement. Some will continuously fire at 10 to 15 Hz even with no joint movement; these are known as static receptors. Type I receptors are slow adapting, so movement effects on them are longer lasting. Their functions include:

• perception of posture and movement
• reflex modulation of postural background and movement through constant monitoring of outer joint tension
• inhibition of centripetal flow from pain receptors via an enkephalinergic synaptic interneuron
• tonic effects on lower motor neuron pools involved in neck, limb, jaw, and eye muscles

This relationship between cervical joint innervation and musculature in the limbs, jaw and eye helps us better understand how Chiropractic adjustive therapy achieves results with complaints such as shoulder and temporomandibular joint pain and diplopia. Additionally, contributions of joint mechanoreceptors to pain perception, posture, and movement, as well as to reflex actions related to the above, would clarify the role of Chiropractic adjustments in treating pain, dystaxia (gait disorders), and postural conditions such as primary kyphosis, scoliosis, thoracic outlet syndrome, etc.

Type II Mechanoreceptors

Type II Mechanoreceptors are found within the deeper layers of the joint capsule. They also have a low threshold (dynamic), sensing even minor changes in inner joint tension. But unlike type I mechanoreceptors, they are very rapidly adapting (accelerator); firing may cease within 0.5 second of joint movement. Type II mechanoreceptors are completely inactive in immobilized joints. Functions of type II mechanoreceptors appear to include

• monitoring of joint movement for reflex actions and perhaps perceptual sensations
• inhibition of centripetal flow from pain receptors via enkephalinergic synaptic interneuron
• phasic effects on lower motor neuron pools involved in neck, limbs, jaw, and eye movement

Type III Mechanoreceptors

These mechanoreceptors are, interestingly enough, completely absent from all spinal joints. They are slow adaptors with a very high threshold and appear to be the joint version of golgi tendon organs, which have an inhibitory effect on motoneurons.

Type IV Receptors for Nociception

Type IV receptors are associated with pain perception. They possess an intimate physical relationship with the type I and II mechanoreceptors and are omnipresent throughout the fibrous portion of the joint capsule and the ligaments of the spine but are absent from articular cartilage. They are very high threshold receptors and are, of course, completely inactive in the physiologically normal joint. Joint capsule pressure, narrowing of the intervertebral disc, fracture of the vertebral body, dislocation of the apophyseal joints, chemical irritation, and interstitial edema associated with acute and/or chronic inflammation may all activate the nociceptive system. The basic functions of these spinal nociceptors include

• evocation of pain
• tonic effects on neck, limb, jaw and eye muscles
• provision of central reflex connections for pain inhibition
• provision of central reflex connections for myriad autonomic effects