Difference Between UMN and LMN
UMN (Upper Motor Neuron) is a form of motor neuron whose cell body is located in the motor area of cerebral cortex. The UMN connects the brain to some level of the spinal cord. The processes of these Neurons remain coupled with nuclei of the motor area in the anterior horn or in the brain stem of spinal cord. These neurons transport information from the brain to specific muscles. These signals are transported to other portions of the body using the help of other neurons which help in the operations of different body parts after they are interpreted by the body receptors.
Spinal and Cranial nerves are called LMN whose cell body is located in main brain stem areas. They can go from brain system of the body and can surpass a chemical signal to some other body parts like muscles or neurons. As the spinal nerves are mixed nerves, they have a component of Lower Motor Neuron. However not all the cranial nerves are components of LMN.
When any of these motor neuron systems fails to work or the path of these motor neurons get damaged a group of symptoms called syndrome are seen. Most of the problems caused in these motor neuron systems happen due to some injury and the problems related to UMN and LMN can be classified by different symptoms including problems in reflexes and also improper operations and in the event of marginal amount of movement in different body parts. UMN and LMN work together. The signals which are formed and transferred from Upper Motor Neuron enter the Lower Motor Neuron system and after that they get further distributed to those body parts where action needs to be performed.
While UMN originates in of Cerebral Cortex region of Brain and the information is transferred to different body parts, LMN are located in the lowest position in the Motor System and receive inputs from higher portion of the neuron system. While the UMN are distributed in extra pyramidal and pyramidal systems, LMN are found in a few Horn Cells and neurons related to Anterior Horn Cells in a few cranial nerves. The UMN systems connect brain with spinal cord through which signals pass to different muscles. The LMN receive signals from UMN and transport them to other body parts. The LMN gives signals to muscle fibers that allow the muscles to act as per the instructions of the nervous system. Unlike the UMN which is of one type of neuron, LMN comprises of two different types of Neurons.