Do you assess prone extension and supine flexion? Part 1
Written by Cheri Dotterer
Neural development is such a complex part of human anatomy. Understanding what is normal or typical should look like if the first step to analyzing what abnormal can be.
OTs, I have a question for you. How many of you do an assessment of prone extension and supine flexion? Are you aware that they are causally related to a pair of primitive reflexes?
Before I tell you which ones, let’s first define one of the terms associated with many of these reflexes, tonic. A tonic reflex is “the occurrence of an appreciable interval after the production of a reflex before relaxation” (Farlex, 2020).
Do you recall your neuroanatomy? Every synaptic transfer begins with the potential for a message to move from one neuron to another. This potential is called the action potential. It is the electrical surge generated by one nerve to the next.
A lower motor neuron tonic reflex is the knee jerk response. That is the one when you use the reflex hammer and strike the patella, the knee extends in a normal or typical response. If the knee does not or is sluggish at responding, there is a neural condition interfering with the neuromuscular response.
I am not saying that primitive reflexes are all lower motor neuron responses. I am using that interaction to describe how a tonic reflex works. An action potential occurs yielding a motor response.
Understanding that primitive reflexes have an action potential followed by a motor response is necessary to understand how they interact in humans. The concern is when these reflexes are not integrated beyond their typical time frames. The action potential and motor responses resemble behaviors that we are not interested in seeing in the classroom. Let’s be clear, these responses that seem to be behaviors cannot be controlled by the student. They are spontaneous reactions to the tonic reflex.
To get the answer to the question I raised above, which primitive reflexes are associated with prone extension and supine flexion. Check back next week for the answer.
Farlex, Inc. (2020). Definition of tonic reflex. Retrieved from https://medical-dictionary.thefreedictionary.com /tonic+reflex#:~:text= the%20occurrence%20of%20an%20appreciable,time%20after%20a%20knee%20jerk.
Purves, D., Augustine, G. A., Fitzpatrick, D., Hall, W. C., LaMantia, A., & White, L. E. (2012). Neuroscience Sunderland, MA: Sinauer Associates, Inc.