Corticospinal Tract, fun facts Flashcards
Simple Finger Movements —>
Activate motor cortex and somatosensory cortex
Complex Finger Movements —>
Premotor cortex and supplemental motor cortex are activated
Rehearsed Finger Movements —>
only activate the supplemental cortex
Start of the corticospinal tract?
Pyramidal cells layer 5 of precentral gyrus
End of the corticospinal tract?
Contralateral anterior horn of the spinal cord where the UMN synapse on alpha/gamma LMNs
UMN tract?
Located in layer 5 and sends axons down the pyramidal tract to the contralateral ventral horn to synapse on the LMN
LMN tract?
Exit from the ventral horn and extend to innervate the target muscle
LMN lesions?
1) Paralysis or Paresis
2) Areflexia (or hypoflexia)
3) Muscle atrophy and wasting due to denervation
4) Denervation may also cause faciculations (twitches) which show up as fibrilations on EMG
5) ALL IPSILATERAL to the side of the damage
UMN lesions?
1) Initially—-> flacicdity and areflexia due to spinal shock
2) but after a few weeks –> spinal cord circuits regain function and the motor signs and symptoms emerge
3) Spastic paralysis (increase in muscle tone)
4) NO WASTING OF MUSCLES
5) Positive Babinski Reflex
6) Hyperreflexia
7) Lesion above decussation —> contralateral symptoms
8) Lesion below decussation —> ipsilateral symptoms
Paraplegia, trauma causing?
Often a result of trauma causing a bilateral impairment of the spinal cord
Cells of the long tracts are cut or crushed-contusion, compression or laceration.
This is an UPPER MOTOR NEURON IMPAIRMENT
Symptoms of paraplegia?
Flaccid paralysis below the lesion (spinal shock) followed by development of spasticity
Increased deep tendon reflex and clonus
Positive babinski reflex
urine retention, painless bladder distention and overflow
decrease of flexor spasms several months after injury
loss of all somatosensory below
