1. Upper and Lower motor neurons
Németh Orsolya

2. Carry motor informations to lower motor neurons
Upper motor neuron:
Carry motor informations to lower motor neurons
Originates in primary motor cortex
Pass through the brainstem
Decussates in medulla oblongata
decussate → lateral corticospinal tract
do not decussate → ventral corticospinal tract
Terminate in spinal cord

3. Upper motor neuron pathways:
Corticobulbar tract

4. Innervate muscle fibers (link between upper neurons and muscle fibers)
Lower motorneuron:
Recieves motor commands from upper motor neuron, send them to muscle fibers
Innervate muscle fibers (link between upper neurons and muscle fibers)
3 types :
α-motor neuron: extrafusal muscle → initiating contraction
β-motor neuron: intrafusal fibers with collaterals to extrafusal fibers
γ-motor neuron: intrafusal muscle fiber → forming muscle spindle with sensory afferents

5. Deseases: Upper motor neuron lesions: „pyramidal insufficiency” stroke, multiple sclerosis, traumatic brain injury, cerebral palsy, Amyotrophic lateral sclerosis (ALS) sympthoms: muscle weakness, decreased motor controll, increased deep tendon,Clasp-knife response, Babinski sign Lower motor neuron lesions: affect nerve fibers from ventral horn of SC sympthoms: muscle paralysis, fasciculations, fibrillation hypotonia, hyporeflexia, decreased strength