Upper Motor Lesion and Lower Motor Lesion

Determining where the signal is damaged

In many injuries and diseases involving the nervous system, you may hear them described as Upper motor neuron lesions (UMNL) or Lower motor neuron lesions(LMNL). These terms are used to describe what point along the pathway is affected. The pathways control: muscle tone, reflexes, posture and voluntary movements. To get an nice overview we will first look at the 2 different types of neurons then we will compare the signs and symptoms of both neuron lesions.

Upper Motor Neuron

Upper motor neurons are present in the cerebral cortex and also the brainstem, they carry information down through the spinal chord to activate interneurons and also lower motor neurons which ultimately signal muscles to contract or relax.

Lower Motor Neuron

These types of neurons are located in the spinal cord and go to the skeletal muscle. They collect the transmitted motor impulses from the upper motor neuron to the skeletal muscles.

UMNL Vs LMNL

Now we know what both of them are, we can also define lesions to these neurons, so an upper motor neuron lesion is the lesion that occurs in the neural pathway above the spinal cord; whereas a lower motor neuron lesion affects the nerve fibres that travel from or below the spinal cord to the associated muscle.

Signs and Symptoms

The Bottom Line…

Osteopaths use this type of knowledge to help determine what type of nerve injury has occurred to a patient and neurologists use this information in order to determine what investigations are appropriate and which treatment would be effective.