Spinal Cord & Motor Control Flashcards
Vertebral level and spinal cord level
C1-C2 V: C1-C2
C3-C7 V: C3-C8
T1-T2 V: T1-T2
T3-T10 V: T3-T12
T10-T12 V: L1-L5
L1 V: tip of spinal cord
Below L2 V: Cauda equina
Ascending tracts pathways
DCML - posterior
ALS - posterior and lateral
Descending tracts pathways
CCS - anterior and lateral
Stretch reflex
Mono synaptic - test by hitting tendon of muscle (sensory input)
Spinal reflexes
Requires a sensory stimulus!
Mono and polysynapatic
Anterior Horn Cell
Is considered the final common pathway - multiple inputs
Spinal cord lesion - at the level of the lesion
LMN signs:
Focal weakness, atrophy, decreased tone and absent reflexes
Spinal cord lesion - Below the level of the lesion
UMN signs:
More diffuse weakness, atrophy only over time, increased tone and reflexes
Physiology of Tone
Nonneural components: passive stiffness
Neural components: stretch reflex and descending influences from the AHC
Hypertonia
abnormally increased resistance to passive lengthening of a muscle that is not attributed to pain
Spasticity or rigidity
Decorticate vd decerebrate lesion location
Decerebrate - below red nucleus
Decorticate - above red nucleus
Pathophysiology of spasticity
Increased input from sensory and descending drive after a lesion that results in an increased output to the spinal cord
imbalance of excitatory and inhibitory influences from reticule and vestibulospinal pathways
When do monosynaptic reflexes return
1-4 weeks (initial hyperreflexia)
When do polysynaptic reflexes return
1-2 days (initial reflex return)
When will no reflexes be present
Spinal shock (24-72 hours)
Requirements of bipedal locomotion
- ability for reciprocal LE movement
- Postural control
- Initiation (of flexion and extension)
- Adaptability
Role of CPGs
Located within grey matter and are connected via commissural fibers
Pattern generators! Help with Reciprocal movement
CPGs three major components
- Rhythm generating network
- Flexor-extensor alternation
- Networks securing left-right alternation
NOT dependent on but its modulated by sensory input
Propriospinal Interneurons and Networks
Communicate information over short and long distances in the spinal cord
Coordinate different parts of the body by linking motor circuits (arms swing with leg swing)
Connects CPGs! and allows for sensory input to modulate output
What does the hip flexor stretch help
Helps facilitate the transition from stance phase to swing phase
What does the supraspinal center help control
Initiation of walking via MLR
Adjustment to errors during walking
Visual guidance and obstacle avoidance via visual and motor cortex
Role of basal ganglia in the supraspinal center
Action selection
Role of MLR and reticulospinal neurons in the supraspinal center
Initiate locomotion
Role of spinal CPGs and networks in the supraspinal center
Generate rhythm and pattern
Role of muscle and skin in the supraspinal center
Modulates ongoing locomotor activity
Role of cerebellar motor circuts in the supraspinal center
Adapt for external perturbations
Role of motor and premotor cortex in the supraspinal center
Obstacle avoidance
Examples of sensory stimuli to drive CPGs
Hip flexor stretch
Weight bearing
Visual cues
Perturbations for adaptations
