Session 4 Flashcards
a feedforward and feedback system among muscle spindles, golgi tendon organs, and joint receptors resulting in info about one’s muscle length and tension with resultant knowledge of one’s position in space
proprioception
a proprioceptor located within skeletal muscle providing constant feedback about changes in muscle length, muscle tension and muscle tone
muscle spindle (aka stretch receptor)
which type of muscle fibers are muscle spindles made of?
intrafusal muscle fibers
name the 2 types of muscle spindle sensory endings.
1a - primary endings
11 - secondary endings
a proprioceptor located at the junction of the muscle and tendon providing info about and detection of muscle tension or force in the tendon of a contracting muscle
golgi tendon organ (gto)
a specialized mechanoreceptor located in the joint capsule providing info about one’s position in space.
joint receptors
name 6 steps of sequences of muscle spindle activity.
- stretch occurs in skeletal muscle or extrafusal muscle fibers
- causes stretch of intrafusal muscle fibers or muscle spindle
- results in firing of 1a and II secondary endings
- proprioceptive sensory info proceeds into dorsal horn of the spinal cord.
- Ia and II fibers synapse with alpha motor neuron (AMN - aka lower motor neuron) in ventral horn of the spinal cord.
- then to one of 4 locations…
AMN of the same muscle AKA agonist muscle to facilitate muscle contraction
autogenic excitation
AMN of opposing muscle AKA antagonist muscle to inhibit muscle contraction
reciprocal inhibition
inhibit synergistic movement and allow isolated muscle control
renshaw cells
relay info about muscle length and position to regulate movement
tracts to cerebellum (Spinocerebellar and cuneocerebellar)
name the 1 GTO sensory ending.
Ib afferent endings
name 4 steps in the sequence of GTO activity.
- GTO detects muscle tension from contracting agonist muscle.
- info sent along Ib afferents into dorsal horn of spinal cord where Ib afferents synapse with interneuron.
- interneuron synapses with alpha motor neuron (AMN) in ventral horn of spinal cord.
- then to one of 3 locations…
inhibit contraction of same muscle aka agonist muscle
autogenic inhibition
name the 3 locations that GTO activity leads to.
- autogenic inhibition
- facilitate contraction of opposing muscle aka antagonist muscle
- to cerebellum to provide proprioceptive info about posture
name the 4 locations that muscle spindle activity leads to.
- autogenic excitation
- reciprocal inhibition
- renshaw cells
- to cerebellum to relay info about muscle length and position to regulate movement
name the 3 types of joint receptor endings
- ruffini endings
- pacinian corpuscle
- ligament receptor
stretch of joint capsule
ruffini endings
movement of joint capsule
pacinian corpuscle
tension of joint capsule
ligament receptor
neurons that regulate muscle length and muscle tone
gamma motor neuron (GMN)
where are GMN found?
ventral horn of SC (Same areas as AMN/LMN) and innervates the muscle spindle
n/a
n/a
name the 4 sequences of GMN activity.
- GMN stimulated in ventral horn
- causes contraction of muscle spindle
- 1a afferents causing AMN of skeletal muscle to fire
- results in contraction of skeletal muscle
an afferent impulse which causes a stereotypic efferent or motor response; all circuitry occurs at the spinal cord level, so NO cortical involvement
spinal reflex arc
is there cortical involvement in a spinal reflex arc?
NO CORTICAL INVOLVEMENT
- function of voluntary motor control
- starts at primary motor cortex and synapses with LMN and AMN
lateral (and anterior) corticospinal tracts
regulation of facilitation and inhibition of muscle tone, posture, and stance.
vestibulospinal and rubrospinal tracts
name the 4 decending motor SC tracts.
- lateral (and anterior) corticospinal tracts
- vestibulospinal and rubrospinal tracts
where do the lateral (and anterior) corticospinal tracts descend from?
cortex
where do the vestibulospinal and rubrospinal tracts descend from?
brainstem
an increase in muscle tone due to hyperexcitability of the tonic stretch reflex, characterized by velocity (speed) dependent increase in phasic stretch reflexes.
spasticity
the resistance of muscles to passive stretch or elongation; the amt of tension a muscle has at rest.
muscle tone
destruction of the LMN/AMN and connection to the skeletal muscle
LMN lesion
name 3 effects of a LMN lesion.
- causes flaccid paralysis (motor neuron can no longer elicit a muscle contraction)
- results in muscle atrophy
- LOSS of spinal reflex or spinal reflex arc
neurons that carry info from the cerebral cortex to either cranial nerve nuclei or to the SC LMNs.
UMN
destruction anywhere along the UMN pathway
UMN lesion
name 3 effects of UMN lesions.
- causes hyperrelexive deep tendon reflexes (DTRs)
- causes loss of voluntary motor control resulting in paralysis or paresis
- spasticity (bc spinal reflex arc can still be intact below the level of the lesion and the connection btwn the LMN and the skeletal muscle may also be intact.
name an example of an UMN lesion.
dysfunction from CVA or stroke or any injury or trauma such as TBI or SCI
name an example of a LMN lesion.
hyporeflexive or absent deep tendon reflexes and ALS
name 2 types of hypertonia.
- spasticity
- rigidity
- resistance in PROM in one direction, velocity (speed) dependent, hyperreflexia
- clonus or involuntary, repeating, rhythmic contractions
spasticity
- resistance in PROM in both directions, velocity (speed) independent
- loss or diminished fractionated movement
rigidity
name the the 7 main components of the UE flexor synergy pattern.
- scapular retraction
- scapular elevation
- shoulder abduction (90 degrees)
- shoulder external rotation
- elbow flexion
- supination
- wrist and fingers variable
name 5 aspects of Brunnstrom synergy patterns.
- movement manifested post brain injury
- pattern presents as total limb movement
- progression through patterns is not always clearly demonstrated (variation)
- presence of “associated reactions”
- stages of recovery (may be used for documentation of levels of severity)
often uses to describe motor capability in rehab settings
brunnstrom 6 stages of recovery
