Upper motor neuron(UMN) connect the motor cortex of the brain to the muscles. The upper motor neurons originate within the motor cortex and then travels down the spinal cord within the corticospinal tracts. Approximately 85% of upper motor neurons cross over to the contralateral side in the brainstem and then travel within the lateral corticospinal tract. The other 15% cross within the spinal cord and are carried within the medial corticospinal tract. UMN is responsible for initiation of voluntary movement and muscle tone.
There are several reflexes to test the UMN: Babinski Sign, Clonus, Romberg test, Inverted Supinator.
Babinski Sign: The therapist stimulates the outside portion of the sole from heel to the big toe. If the Toe is going up and the other fingers fan out the Babinski Sign is positive and there may be some Neurological problem.
Clonus sign: Clonus can be described as neurological state that causes involuntary muscle contract. What we see is rhythmic uncontrolled movement. The main site that clonus can be seen is knees and ankles; but it can also be spotted at the fingers and elbow. In order to evoke this reflex, it is only needed to excessively stretch the muscle responsible for the movement. In order to test for clonus in the ankle the therapist will rapidly bring the foot into Dorsiflexion (stretching Gastrocnemius) and if the sign is positive, there will be pounding movement of the foot up and down as a result.
Romberg test: is used to test neurological components of patient’s balance in absence of other inputs (like visual or vestibular). The patient needs to maintain balance while standing heel to toe with his/her eyes closed. If the balance is maintained and there is no increase sway, then the test is negative but if there is a significant sway or the patient cannot hold the balance then the test is positive.
Inverted Supinator: Considered a good test for spinal cord injury at C5/C6. This test is done by taping on the distal portion of brachio-radialis tendon. The test is considered positive in 2 cases if there is fingers flexion or absence of reaction of brachioradial muscle.
For proper assessment and treatment, please contact your physiotherapist or health provider.
