Tbi-Tracts And Spasticity

Front 1

Name 2 mechanisms for spasticity

Back 1

1) Myoplastic Hyperstiffness (mechanical component)

2) Reflex activity of muscle spindles (neural component)

Front 2

What 5 things describe myoplastic hyperstiffness?

Back 2

1) Weak actin/myosin bonds
2) Decrease in # of sarcomeres due to immobility
3) Increase # of crossbridges due to immobility
4) Decrease elasticity of titin due to decrease sarcomeres
5) Replacement of muscle fibers with CT (collagen) due to immobility/atrophy

Front 3

Where do alpha and gamma neurons reside?

Back 3

Ventral horn of the SC, affected by descending motor systems

Front 4

What do alpha motor neurons innervate?

Back 4

Extrafusal muscle fibers to cause contractions

Front 5

What do gamma neurons innervate?

Back 5

Intrafusal muscle fibers at the polar ends of the muscle spindle

Front 6

What 3 things can descending motor systems affect?

Back 6

1) alpha and gamma motor neurons
2) Muscle spindles
3) Interneurons

Front 7

What controls descending systems?

Back 7

BG and cerebellum

Front 8

Name 7 descending motor systems

Back 8

1) Vestibulopsinal
2) Reticulospinal
3) Corticospinal
4) Rubrospinal
5) Tectospinal
6) Raphospinal
7) Ceruliospinal

Front 9

Where does the medial vestibulospinal tract originate and innervate?

Back 9

Origin: Vestibular nuclei in medulla

Innervate: head, neck and trunk extensors for posture

Front 10

Where does the lateral vestibulospinal tract originate and innervate?

Back 10

Origin: Vestibular nuclei in medulla

Innervate: UE/LE extensors for posture (decerebrate posture)

Front 11

What descending tracts contribute to decerebrate posturing?

Back 11

M/LVST
Reticulospinal tracts

Front 12

Where does the medial reticulospinal tract originate and innervate?

Back 12

Origin: Pons, reticular formation

Innervation: Head, neck and trunk extensors for posture

Front 13

Where does the lateral reticulospinal tract originate and innervate?

Back 13

Origin: Pons, reticular formation

Innervation: UE/LE either flexors or extensors to inhibit or facilitate movement

Front 14

What descending tract can either flex or extend extremities?

Back 14

Lateral Reticulospinal Tract

Front 15

What descending tract can either inhibit or facilitate movement?

Back 15

Lateral Reticulospinal Tract

Front 16

Where does the medial corticospinal tract originate and innervate?

Back 16

Origin: Cortex

Innervation: Trunk muscles

Front 17

Where does the lateral corticospinal tract originate and innervate?

Back 17

Origin: Cortex

Innervation: Fractionated movements (isolated joint motions)

Front 18

What do CST directly influence?

Back 18

Alpha and gamma motor neurons

Front 19

Where do the rubrospinal tracts originate and innervate?

Back 19

Origin: Red nucleus in midbrain

Innervation: UE/LE flexors (esp. UE)

Front 20

What descending tracts display decorticate posturing?

Back 20

Rubrospinal Tracts (esp. UE)

Front 21

Where do the tectospinal tracts originate and innervate?

Back 21

Origin: Superior Colliculus in midbrain

Innervation: Cervical muscles to move the head toward stimulus of sounds or visual input

Front 22

What descending tracts primarily control posture and proximal movements?

Back 22

1) MCST
2) Medial Rectulospinal
3) M/LVST
4) Tectospinal

Front 23

What 2 tracts are non-specific and influence other tracts based on emotions from the limbic system?

Back 23

1) Raphospinal
2) Ceruliospinal

Front 24

What are 3 different types of fibers within a muscle spindle?

Back 24

1) Static nuclear bag fiber
2) Static nuclear chain fiber
3) Dynamic nuclear bag fiber

Front 25

What fibers of the muscle spindle gives info about the length of the muscle?

Back 25

Static nuclear bag fiber

Static nuclear chain fiber

Front 26

What muscle fiber of the spindle gives info about the velocity or rate of change of dynamic movement?

Back 26

Dynamic nuclear bag fiber

Front 27

Which fibers are the "wind up" stretch of a muscle used in PNF?

Back 27

Static nuclear bag fiber

Static nuclear chain fiber

Front 28

What fiber give the "quick stretch" info in PNF?

Back 28

Dynamic nuclear bag fiber

Front 29

What is the purpose of gamma motor fibers?

Back 29

Sets the sensitivity threshold controlled by descending systems

Maintains a certain tension on spindle

Front 30

What are gamma motor fibers?

Back 30

Efferent neurons from the ventral horn of SC connecting to polar ends (intrafusal) to keep muscles at a certain tension

Front 31

Name 2 types of gamma motor neurons and what their function is.

Back 31

1) Static--function when at rest as background tone

2) Dynamic--function more when movement occurs

Front 32

When muscle contracts, what happens to the gamma motor neurons?

Back 32

Alpha neurons shorten extrafusal fibers

Gamma neurons shorten intrafusal fibers to give feedback on how active the muscle is

Front 33

What do type Ia afferent endings wrap around?

Back 33

Static nuclear chain fibers, static nuclear bag fibers and dynamic nuclear bag--all of the muscle fibers to give info about velocity, dynamic movement and quick stretch

Front 34

What type of afferent endings give info about velocity and dynamic movement?

Back 34

Type Ia afferents

Front 35

What type of afferent endings give info about the quick stretch in PNF?

Back 35

Type Ia afferents

Front 36

What do type II afferent endings wrap around?

Back 36

Only goes around static nuclear bag fibers and static nuclear chain fibers

Front 37

Describe a monosynaptic reflex or DTR

Back 37

Tap spindle type Ia afferent to discharge in DRG to SC to synapse on alpha motor neuron to contract a muscle

Front 38

What else will alpha motor neurons branch to in SC?

Back 38

1) Other synergists to contract muscles

2) Up SC to cortex and cerebellum

3) Ia inhibitory interneuron

Front 39

What does the Katz article say are the main reasons for spasticity?

Back 39

1) Gamma hyperactivity
2) Alpha hyperactivity

Due to excitation of alpha motor neuron itself or loss of inhibition to different muscles

Front 40

What does the Ia inhibitory interneuron cause?

Back 40

Relative relaxation of the antagonist so the agonist can perform its function of contracting

Front 41

What other areas are Ia inhibitory interneurons receiving info rather just Ia afferents?

Back 41

1) Cutaneous receptors
2) Jt receptors
3) Descending systems

Front 42

How do WB postures influence spasticity?

Back 42

WB postures provide co-contractions of muscles activating the Ia inhibitory interneuron to receive info from descending systems tell it not to inhibit as much--this controls the degree of inhibition

*Descending systems will override this reflex of inhibitory interneuron (relaxation of antagonist) with voluntary movement

Front 43

Where does the inhibitory factor in the tendon reside and what type of afferents?

Back 43

Golgi Tendon Organ info carried by Ib afferent inhibitory to its own muscle and facilitory on antagonist

Ib afferent inhibitory synapses on AMN

Front 44

What all influence Ib afferent inhibition interneurons?

Back 44

1) Descending systems
2) Jt receptors
3) Cutaneous receptors

Front 45

What tracts are the moderator of the Ia and Ib inhibitory interneurons?

Back 45

CST

*CST is often affected with TBI and allows others to influence Ib interneurons

Front 46

What is the therapeutic reason for using joint and cutaneous receptors to reduce spasticity?

Back 46

Periphal jt and cutaneous receptors can modify or change what happens reflexively

Front 47

What is the cause of spasticity?

Back 47

Decrease of inhibition interneurons b/c lack of descending influence or different descending input Ia or Ib inhibitory interneurons or from muscle co-contraction