Motor Control And The Corticospinal Tract Flashcards
What are the two types of motor pathway?
Voluntary = pyramidal
Involuntary = extrapyramidal
Where do axons leave the cerebrum from in the cortiscospinal tract?
Precentral gyrus (primary motor cortex)
Supplementary motor cortex
And premotor cortex
After leaving the motor cortex, what happens to nerve fibres?
They descend to the brainstem from the UMN via the internal capsule (posterior limb) in the brain (white matter) where 85% of fibres decussate in the pyramids of the medulla to the lateral corticospinal tract
(Limb control)
The remainder descends in the anterior corticospinal tract
What happens to nerve fibres when they leave the brainstem?
85% have dessucated in the pyramids and descended in the lateral corticospinal tract, where they then synapse with a LMN in the ventral horn of the vertebrae
15% descend in the anterior corticospinal tract until they decussate tag segmental level in the vertebrae, and synapse with LMN in the ventral horn of vertebrae.
What is -plegia vs -pariesis
What is mono, hemi, quad and para?
Plegia = complete paralysis
Pariesis = partial paralysis
Mono = one limb
Hemi = one leg and one limb
Para = both legs
Quad = all four limbs
What occurs if damage is done to the corticospinal tract pons vs the medulla?
Damage to the pons = before it has decussated. So damage is done contra-laterally. Results in hemiplegia or hemipariesis
Damage in the medulla = after decussation, so damage is done ipsilaterally. Resulting in hemiplegia or hemipariesis
What may cause UMN syndrome? What indications would occur?
Stroke, MS, Vit B-12 deficiency
Clonus - repeated involuntary muscle contractions
Hyperreflexia
Hypertonia - exaggerated muscle tone
Babinski sign - sharp touch to lateral aspect of foot results in dorsiflexion of foot and fanning of the toes. May indicate upper motor neurone disease.
