A good example of the protective nature of the CER is when a person steps on a nail. Staying consistent with the above example, consider that the nail pierced the person’s left foot. The nociception-filled left foot immediately pulls away from the noxious stimulus while the right leg sustains the weight of the whole body.
When the reflex occurs, the flexors in the withdrawing limb contract and the extensors relax, while in the other limb, the opposite occurs.
Brain-Based Solutions™ for the Crossed Cord Reflex
The Importance of Reciprocity to Human Performance (Part 4 of 5)
Therefore, when a potentially injurious stimulus occurs, the protective reflex response of moving away from the potentially dangerous stimulation happens much faster than the conscious recognition of the insult.
Nociception is always present, everyone has it. However, nociception is kept under control by many factors. Joint motion, chemical signals, hormones, etc., all stifle nociception until something disrupts their controls. It is only then that nociception is allowed to reach conscious levels and one realizes pain.
The Crossed Extensor Reflex (CER; also known as the crossed cord reflex) is another example of a protective response (recall that the flexor withdrawal response—part 3 of 5—is also considered protective) that apparently begins at about 28 weeks gestation and is said to be neurologically integrated one to two months after birth. It is functionally significant in reciprocal muscle actions. Its dysfunction can interfere with activities like running and kicking, and other functional events.
Of the cord’s 12 responses to a primary afferent (discussed in, “Cortical release signs: the modified Galant reflex using applied kinesiology as functional neurology”, available from healthbuilders.com), eight of them have to do with muscles. This means that three quarters (75 percent) of the cord responses to incoming signals have to do with muscle function.
While both the CER and FWR are protective, the CER generates the reciprocal activity of the FWR. Where stroking the sole of one foot with a sharp object causes the physiological withdrawal of the ipsilateral foot from the stimulus, the reciprocal CER response causes physiological extension of the contralateral leg. That is, the stimulus causes functional facilitation of the proximal aspect of the ipsilateral rectus femoris; it also causes the functional inhibition of the proximal aspect of the ipsilateral hamstrings and proximal aspect of the contralateral rectus femoris, with a simultaneous facilitation of the contralateral hamstrings.
sole of his left foot with a sharp object caused functional facilitation of his ipsilateral rectus femoris (a group test; for more information, see the videos on the "Spinal Pattern Generator") and hamstrings, with a concomitant conditional facilitation of the hamstrings and conditional inhibition of the rectus femoris, contralaterally. This indicated a left-sided pathological response.
In this case, manipulation of the left talocalcaneal joint reset Adam’s dysfunctional CER and his pain immediately ceased. A recheck of the lower extremity CER showed its response to be as anticipated, bilaterally.
It appears that while the left rectus femoris, and the right rectus femoris and hamstrings were responding as expected, the left hamstrings displayed an inappropriate facilitation. This could have lead to the dysfunctional facilitation of the left hamstrings from the ischium leading to Adam’s experience of pain.
Here is what happens: The nociception causes physiological facilitation of the ipsilateral proximal rectus femoris while that ipsilateral proximal hamstring gets physiologically inhibited, allowing the thigh to flex on the hip. Simultaneously, the ipsilateral distal rectus femoris physiologically inhibits while the ipsilateral distal hamstring physiologically facilitates, causing the left lower extremity to flex at the hip and knee. Meanwhile, the right proximal hamstrings physiologically facilitates at the hip and physiologically inhibits at the knee while that ipsilateral rectus femoris physiologically facilitates at its distal aspect and physiologically inhibits at its proximal aspect thereby causing the right lower extremity to become like a compliant pillar to resist gravity.
Another example is touching a hot stove with the hand. As we saw with the FWR (article 3 of 5), the burned hand violently pulls back while the other hand extends to push away from the stimulus. On the affected side, the arm physiologically flexes at the shoulder and elbow while the reciprocal happens contralaterally: there is physiological extension at the shoulder and elbow. Further, the protection also involves the lower extremities causing a step backward with the leg ipsilateral to the stimulus.
Adam’s functional neurological response to the repetitive nociception revealed an excellent example of how a dysfunctional FWR generates a concomitant CER that may or may not be pathological. In this case, the FWR display contralateral to stroking the right foot was appropriate, the pathological response remaining within the left lower extremity when sole of the foot was stroked ipsilaterally.
With each step, the subluxation reduced the primary afferents from the left ankle leading to an inability to inhibit the nociceptive reflexogenic afferents in the dorsal cord, leading to Adam’s perception of pain in the area of the ipsilateral proximal hamstrings. (For more information about nociception and the perception of pain, see the articles entitled, ““An Overview of the Clinical Aspects of Vertebral Coupling,” “Deafferentation vs. Pinched Nerves,” and “The Neurological Implications of the Chiropractic Adjustment.”)
A reflex is a swift and pre-programmed movement pattern that occurs in response to some sort of stimulus applied to the periphery and transmitted to the brain and/or spinal cord before you even realize you are responding to it.
Consider the movement of a reflexive response. The sensory impulses that convey some sort of neurological insult (e.g., nociception, the unconscious recognition of pain) travel at about 0.5 meters (less than two feet) per second.
Conversely, those sensory impulses that convey joint position sense (proprioceptors) travel faster than the length of a football field (120 meters, almost 400 feet) in one second.