Spinal cord Flashcards
muscle synergy
coordinated muscular action
reciprocal inhibition
the inhibition of antagonist muscles during agonist contraction
- achieved by interneurons in the spinal cord
medially located pools in the spinal cord
innervate axial and girdle muscles
laterally located pools in the spinal cord
innervate distal limb muscles
posterior pools in the spinal cord
innervate flexor muscles
anterior pools in the spinal cord
innervate extensor muscles
phasic stretch reflex
response to the stimulus is brief
tonic stretch reflex
response last as long as the stimulus
myostatic reflex
same as phasic stretch reflex
–> from the muscle spindle(1a)–>dorsal horn–>ventral horn–>alpha motor neuron
- signal also goes to the cortex
3 actions to facilitate a contraction
1) quick stretch
2) tapping muscle
3) reflex
flexor withdrawal
occurs with you have a painful stimulus(hot stove)
- purpose is to pull the body away from painful stimulus to prevent tissue damage
- causes flexion
- nociceptive reflex
crossed extensor
- purpose is to keep you away from painful stimulus after flexor withdrawal(stepping back, hopping)
- allow time to develop new strategy to stay away
Lamina 1
marginal layer
- noxious stimuli
Lamina 2
substantia gelatinosa
- noxious stimuli
lamina 3 and 4
nucleus proprius
- proprioception and 2-point discrimination
lamina 5
noxious stimuli and info about viscera
lamina 6
proprioception info
lamina 7
nucleus dorsalis or Clarke’s column
- proprioception and relays unconscious proprioception
lamina 8
connect with the contralateral cord and brain
lamina 9
contains cell bodies of LMN’s
Lamina 10
axons crossing to the opposite side of the cord
stepping pattern generators
stepping by activating LMN’s, eliciting alternating flexion and extension at the hips and knees
reciprocal inhibition
decreases activity in an antagonist when an agonist is active
recurrent inhibition
inhibition of agonists and synergists, with disinhibition of antagonists
segmental lesion
interfere with neural function only at the level of the lesion
vertical tract lesion
loss of function below the level of the lesion
white matter lesion
affects everything below that level
gray matter lesion
affects just that level
cervical cord lesion
tetraplegia(quadraplegia)
- C5-T1 involvement of the arm
lesion of the spinal cord below the cervical region
paraplegia(below T1)
- loss of motor or sensory to LE
peripheral nerve lesion signs
1) altered or loss of sensation
2) decrease or loss of muscle power
3) no vertical tract signs
segmental lesion signs
1) altered or lost sensation in a dermatome
2) decreased or lost muscle power in a myotome
3) decreased or lost sensation below the lesion
spinal region vertical tract signs
1) altered or lost sensation below lesion
2) altered or lost descending control of BP, viscera, and thermoregulation
3) UMN’s signs
anterior cord syndrome
interrupts ascending spinothalamic tracts and descending motor tracts
- pain and temp, voluntary movement, trunk control loss below lesion
- no loss of proprioception and discriminative touch(posterior cord)
- paraplegia, spastic paralysis, bilateral motor loss below lesion
central cord syndrome
- no motor loss
- loss of pain and temp of arms(spinothalamic)
- just at level of injury
syringomyelia
central canal swells
- disrupts pain and temp(crossing fibers) at the level of expansion(arms)
- progression will compress motor to lower limbs
- can be caused by a tumor
Brown-Sequard syndrome
hemisection of the cord(affects dorsal column, lateral corticospinal, spinothalamic)
1) ipsilateral UMN signs below the level of lesion
2) ipsilateral loss of proprioception, 2-point discrimination, vibration(dorsal column)
3) contralateral loss of pain and temp
4) ipsilateral LMN at the level of lesion
5) ipsilateral cutaneous anesthesia at the segmental level
Fredreich’s ataxia
genetic
- affects corticospinal tracts = no voluntary movement(spastic paralysis), no reflexes
- affects dorsal column
- affect spinocerebellar tracts = no unconscious proprioception
cauda equina syndrome
damage to the lumbar and/or sacral spinal roots
- sensory impairment and flaccid paresis or paralysis of lower limb muscles, bladder, and bowels
