Pt 6221 - Facilitated Segment

Front 1

What changes may indicate spinal dysfunction?

Back 1

1. range of motion
2. local tissue texture
3. local muscle tone
4. sensitivity
5. skin drag

Front 2

What is segmental facilitation?

Back 2

-Result of a disturbance in the afferent input into spinal segment.
-muscular system receives and inputs information to CNS
-ANS and cerebral cortex influenced
-Altered input alters excitation threshold (threshold is lowered, therefore more responsive to stimuli) = increased excitability of spinal segment
-may even respond to abnormal stimulus
-Theories of facilitation = chronic release of NT's, failure to release enzymes breaking down NT's

Front 3

Process of Facilitated Segment

Back 3

1. Barrage of C-fibre input - more excitatory AA's and peptides
2. Leaky membrane - Calcium influx into dorsal horn
3. Activate NO synthase --> more NO
4. Release Substance P
5. Enhanced sensitivity of NS and WDR Neurons
6. Hyperalgesia

Front 4

Causes of facilitated segment causing chronic input

Back 4

1. spinal dysfunction
2. excessive afferent signal

Front 5

Osteopathic Lesion

Back 5

Representing a facilitated segment of SC maintained in that state by afferent impulses. ALL structures receiving efferent output from that segment are potentially exposed to excessive excitation or inhibition

Front 6

Clinical observation of facilitated segment

Back 6

Reflex threshold, sensory threshold, motor control threshold in spinal cord LOWERED

All tissues, somatic or visceral sensitized by internal or external stimuli

Front 7

Types of stimuli that enter a neuron pool
1. Threshold Stimuli
2. Sub Threshold Stimuli

Back 7

1. causes actual excitation
2. Fails to excite neuron but makes it more sensitive to impulses from other sources

*Neuron made more excitable but does not discharge is FACILITATED*

Front 8

Mechanism of Facilitated Segment

Back 8

1. Facilitated Segment
2. Bombardment of SC neurons
3. Summation
4. Increased central excitatory state
5. reduced threshold
6. Exaggerated response of: anterior horn (motor), lateral horn (ANS), sensory level (hyperalgesia)
7. chronic facilitation (trophic changes, muscle fibrosis)

Front 9

Effects of facilitated segment

Back 9

-widespread or localized
-depends on degree of facilitation

Front 10

Changes due to Facilitated Segment
1. Sensory
2. Motor
3. ANS

Back 10

1. Sensory
-hyperaesthesis (allodynia), hyperalgesia
-afferent impulses more easily reach CNS from SC

2. Motor
-Hypertonus, Hyperreflexia,
-fatigability
-Spasm, tension, postural imbalance, pain, motion restriction

3. ANS
-vasoconstriction
-sweat, skin dystrophy and oedema (P'eau d'orange)

Front 11

Clinical Characteristics

Back 11

1. Reduced threshold of pain and touch
2. Vasomotor changes with increased sweat and changes in tissue texture
3. Increased motor activity
4. Increased reflexes

Front 12

Gamma vs. Alpha motor neurons

Back 12

Gamma = supply intrafusal muscle fibres of muscle spindle

Alpha = supply extrafusal muscle fibres

Front 13

Muscle spindle

Back 13

-detects resting length and tone
-Encapsulated, 4-10 mm length
-parallel with extrafusal fibres
-sensory organ wraps around intrafusal fibres
-shortening = reduced MS firing
-lengthening = increased MS firing. Also inputs to alpha motor neuron to contract extrafusal fibres

Front 14

Golgi Tendon Organ

Back 14

-Musculotendinous joint in series with extrafusal fibres and detects tension
-ONE 1b axon enters and then branches unmyelinated
-muscle contraction creates tension and GTO fires
-VERY sensitive

Front 15

2 types of sensory axons:
1. 1a
2. 1b

Back 15

1) 1a = originate from primary or annulospiral receptors

2) 1b = originate from secondary or flower spray receptors

Front 16

Pathway of the 1a sensory axons/1a afferents from muscle spindles?

Back 16

1. monosynaptic connection with alpha MN in ventral roots of SC
2. Homonymic innervation

"Muscle Stretch Reflex"

Front 17

Neuromuscular Control

Back 17

-ability to produce controlled movement through coordinated muscle activity

-results from complex interaction b/w NS and MSK system

Front 18

Feedback control

Back 18

1. Sensors continually measure parameter (length), info to controller (MS), compares to normal value (rest)
2. Error signal if different
3. Compensatory response (homeostasis)

Front 19

Feed-forward Control

Back 19

1. Sensors detect potential disturbances
2. If detected, info to controller indicating impending change
3. Controller institutes signals to counteract anticipated disturbance (based on past experience with similar disturbance)

Front 20

How does the muscle spindle act as a comparator?

Back 20

-gamma efferents: contract IF fibres - decrease MS length. If mm does NOT contract, MS excited and will stretch
-Reduced gamma efferent: relax IF fibres - reduce stretch of MS and reduce excitation of spindle

-Comparator - MS compares length of MS with length of mm around it

-mm length greater than MS: MS excited
-mm length less than MS: MS not excited

Front 21

Muscle spindle and Facilitated Segment

Back 21

-somatic, osteopathic or segmental dysfunction
-one or more spindles controlling joint in that segment "turned up"
-increased gamma MN discharge
-intrafusal fibres in chronically shortened state

-For every EF fibre change, get exaggerated response from MS

Front 22

Assessing Facilitated Segment: Motor
1. Resting tone
2. Stretch reflex
3. Strength test

Back 22

1. Palpation - difference in tone
2. ROM - stretch out isolated muscle
3. applied resistance

Front 23

Assessing Facilitated segment: Sensory
-areas of hyperaesthesia and tenderness

Back 23

Palpation, pin prick, brush sensation, muscle weakness, light pressure/touch

Front 24

Assessing Facilitated Segment: ANS
1. Vasoconstriction
2. Increased sweating
3. Trophic changes in skin

Back 24

1. skin colour, weal response (response to scratch)
2. finger drag along skin
3. skin rolling (edema -leaves an indent due to fluid pooling beneath skin from poor circulation back to the heart)

Front 25

Treatment of Facilitated Segment

Back 25

-eliminate cause
-temporary de-facilitation via repeated active or passive techniques

Front 26

Repeated Active or Passive Technique for Treating Facilitated Segment

Back 26

-maintain tension on hypertonic muscle until they let go
-favour ease of motion and approximate attachment of mm, reducing tension, allow shortening
-disparity b/w IF and EF mm narrows
-shortened MS continues to fire but CNS is gradually enabled to turn down gamma discharge

Front 27

Muscle Energy Technique for Treating Facilitated Segment

Back 27

1. apply corrective force via active muscle contraction
2. push or pull opposing force of PT
3. Isometric contraction
4. increasing tension
5. reset spindle gain to normal levels

Front 28

High Velocity thrust treatment of Facilitated Segment

Back 28

1. Stretch affected muscle against their resistance
2. gapping of joint adds further length and tension

Front 29

Hold Relax Treatment of Facilitated Segment

Back 29

1. Stretching hypertonic muscles in lesioned segment
2. stretches IF fibres
3. barrage of afferent impulse to CNS
4. CNS gamma discharge turned down
5. Intense discharge by GTO causing inhibitory influence
-myofascial release
-return of spindles to normal gain settings