Cutaneous reflex in human locomotion
They have been shown to be important in responses to obstacles or stumbling, in preparing for visually challenging terrain, and for assistance in making adjustments when instability is introduced.
In addition to the role in normal locomotion, cutaneous reflexes are being studied for their potential in enhancing rehabilitation therapy (physiotherapy) for people with gait abnormalities.
There are also reflex pathways involved in more dynamic activities such as walking and running, helping to ensure a smooth gait and allowing us to respond quickly to obstacles or unexpected perturbations or disturbances.
The complexity of the reflex can be estimated by examining the time delay, or latency, between the electrical stimulation of the sensory neuron and the corresponding motor response, as measured by EMG (electromyography).
The response is to quickly pull the foot that stepped on the tack away, and at the same time, shift our weight to the opposite (contralateral) leg for balance.
Superficial branch of radial nerve (innervating forearm and hand on the thumb side) Human locomotion is often examined from the perspective of the gait cycle.
This variation suggests a functional role for the reflex to provide us with a smooth gait alteration when encountering or anticipating obstacles and challenging terrain.
The major muscles impacted involve four (4) motions important to locomotion: for EMG activity Soleus Cutaneous stimulation of the superficial fibular nerve (SF) would typically occur when the top of the foot encounters an obstacle.
In normal, unimpeded walking, TN activation during the transition from stance to swing should decrease as the foot begins to leave the ground.
The sural nerve innervates the lateral (outside) portion of the foot and could be activated during either the swing or stance phase when encountering uneven terrain.
During the stance phase, a moderate intensity SN stimulation is indicative of uneven terrain and will result in a response that provides stiffness and stability to the ankle.
Stimulation of the radial nerve during walking is unusual and often indicative of an obstacle that is high enough to make contact with the swinging arm.
In unstable conditions, such as disturbances occurring when the arms are crossed, there is facilitation or amplification in both the ipsilateral and contralateral reflexes which are muscle specific.
The ability to modulate the magnitude of cutaneous reflexes via rhythmic arm movements or challenging environments has potential implications in rehabilitation for patients with motor weakness.
[13] Future research is needed to further explore the efficacy of cutaneous reflex amplification for as a tool for enhancing motor receptivity with stroke rehabilitation.
