biomech.final Flashcards
(364 cards)
1
Q
A slow deformation of cartilage occurs with what?
A
Creep.
2
Q
What is the syringe effect with cartilage?
A
High speed loading insufficient time to squeeze water out of tissue and the cartilage is very stiff, and little deformation occurs.
3
Q
What will happen to cartilage after you unload a slow load?
A
Immediate restoration to 90% original thickness via elastic recoil. The last 10% comes back slowly.
4
Q
Synovial fluid acts as what?
A
A lubricant between articular surfaces.
5
Q
What are the 2 types of lubricant?
A
Fluid film- thick film of lubricant. Boundary- last resort for cartilage.
6
Q
What is the friction of fluid film?
A
Almost zero.
7
Q
When will hydrodynamic lubrication be used?
A
Non-parallel surfaces with tangential movements.
8
Q
What will hydrodynamic lubrications create?
A
A lifting action keeping surfaces apart and reducing friction.
9
Q
What is squeeze lubricant like and what will it be used for?
A
Surfaces are kept apart and there is a perpendicular force. The viscosity keeps the lubricant toegether. Good for high loads with short durations.
10
Q
What type of lubrication is important in severe loading?
A
Boundary lubrication.
11
Q
How will unwanted material from solid surfaces be removed (in cartilage)?
A
Mechanical action (movement).
12
Q
What are the 2 ways cartilage can wear?
A
interfacial and fatigue.
13
Q
What can cause interfacial wear of cartilage?
A
Interaction of articular surfaces causing adhesions or abrasions.
14
Q
What can cause fatigue wear?
A
With repetitive cyclic loading so reloading before the cartilage has time to fully re-imbibe.
15
Q
What will immobility do to synovial fluid?
A
Decreases the circulation.
16
Q
Degeneration of cartilage promotes what?
A
Further degeneration.
17
Q
What type of failure occurs easily with cartilage?
A
Tensile.
18
Q
What is the repair capacity of cartilage like?
A
Limited.
19
Q
What is the function of muscles?
A
1) Produce motion 2) Support and stability (posture and joint stability) 3) shock absorption 4) proprioception
20
Q
What muscle is continuously active in standing posture?
A
Quadratus lumborum.
21
Q
What would happen to the spine without muscle support?
A
A force of 5 lbs at T1 would permanently displace the spine
22
Q
Tension from muscles is produced where?
A
In the elastic components.
23
Q
What are the two tensions?
A
Active and passive
24
Q
What is active tension?
A
Contractile elements
25
What is passive tension?
The passive element (elastic properties of muscle fiber and fascia)
26
What is contained in a musculotendinous unit?
1) The contractile component (actin and myosin) 2)A primary eleastic component (the tendons) 3) Second elastic component (connective tissue made up of epi, peri and endomysium and sarcolemma in parallel with contractive components
27
What produces tension?
Produced in the elastic components leading to active contraction and passive stretch
28
How is tension released?
When the muscle returns to its resting length
29
What are the parts involved in touching your toes?
Intial muscle stretch is elastic and the further elongation results from viscosity of the muscle-tendon sturcture.
30
What are the benefits of elasticity/distensibility?
1) Allows the contractile element to return to resting postitions after completed contraction 2) Protects the contractile components from passive overstretching and injury 3) Good shock absorber for the muscle
31
What is the force actively caused by a contaction on the bony lever?***
Muscle tension.
32
What is the external force exerted in the muscle?***
The resistance or load.
33
Muscle contraction causes what?***
Rotational force vector at the joint called torque or bending force vector called moment.
34
What are the different types of contraction?
1) Isometric 2) Concentric 3) Eccentric
35
What is the first type of rehab exercise?***
isometric contraction.
36
What is isometric contraction like?
Little or no joint movement and no change in muscle length.
37
What is isometric contraction used for?
Stabilize joints, hold posture against gravity
38
What type of contraction will the muscle shorten and length?
Shorten- concentric. Lengthen- eccentric.
39
What happens to the muscle in a concentric contraction?
Muscle shortens (overcomes resistance)
40
What happens to the joint in a concentric contraction?
Joint moves (ie: quadriceps shorten while walking up stairs)
41
What are some concentric exercises used for?
With the use of machines, tubing, dead weights are used for strength and endurance
42
What happens to the muscle in an eccentric contraction?
Muscle lengthens while contracting (the resistance overcomes the contraction)
43
What is the purpose of an eccentric contraction
To decelerate the motion of the joint to control the movement and dampen any sudden shock on the joint
44
What type of contraction creates the most tension?
Eccentric contraction
45
When should eccentric exercises be introduced in rehab?
Better performed in the later stages of rehab of an injured muscle
46
Rank the relative tension from most to least for muscle contractions
Eccentric > Isometric > concentric
47
When is the maximum tension of a muscle produced?
At its rest length
48
What happens to production as the muscle shortens or lengthens?
It decreases
49
Is the tension production in a muscle variable or the same for an isometric tension
It is variable for different muscle lengths
50
What is the resting length of a muscle where the most tension found?
Optimal overlap between thick and thin filaments and all cross bridges are available to particpate in the contraction
51
Why is the the tension decreased when the muscle is elongated?
There is littler tension developed by the contractile componenet because there is only a slight overlap of thick and thin filaments and the passive is a result of the connective tissue
52
Why is the the tension decreased when the muscle is shortened?
There is a weak contraction, the thick and thin filaments are overlapped too much and restricts productive cross bridle cyclins.
53
The whole muscle tension is what?
A combination of the tension caused by the active contraction of the sarcomere and the passive elastic tension on the other components.
54
Does passive tension in muscles play an important role in everyday activities?
No most muscles only cross one joint and are normally not stretched enough for passive tension to plan an important role
55
What types of muscles does passive tension have an effect on?
Two-joint muscles
56
The total force that a muscle can produce is influenced by what?
The velocity it can attain.
57
For concentric contractions, with a greater load what happens to the velocity of the muscle shortening?
slower
58
For eccentric contractions, type of load causes a faster velocity of the muscle shortening?
Greater load (resistance)
59
What is the force or tension that a muscle can produce promortional to?
Contraction time
60
If the contraction time increases what happens to the force or tension developed?
The greater the force developed
61
What are the mechanical properties for force production of a muscle based on?
1) Length-tension relationship 2) Load- velocity relationship 3) force-time relationship
62
Will a long skinny muscle or a short fat muscle be able to generate more force?
Short fat.
63
Why will short fat muscles be able to generate more force?
More sacromeres lie in parallel and the greater the physiological cross sectional area.
64
The Longer skinny muscles are good at what?
Excursion (lengthening).
65
Why are longer skinny muscles good at excursion?
More sacromeres lie in series and the smaller physiological cross sectional area.
66
How can cross sectional areas be increased?
Physical training.
67
Does a muscle perform more work with concentric contraction starting from a pre-stretched or a resting length?
A pre-stretched state (reason is unknown)
68
What is the concept behind plyometric exercises?
Starting a concentric contraction from a pre-stretched position
69
What is the effects of increased temperature in muscle?
1) Increased enzymatic activity of muscle metabolism leading to increased efficiency of the contraction 2) Increased elasticity (of collagen) leading to a greater pre-stretch effect 3) Increase blood flow to the muscle
70
What are the effects of increased temperature caused by warming up?
1) Increased blood flow to the muscle 2) Release of heat energy from uscle contraction, increased metaboli rate, and friction of contractile elements sliding over each other
71
What are the effects of physical training?
1) Activation of motor pathways 2) increase in cross sectional area of muscle fibers (cells) 3) Relative percentage of fiber types may also change
72
Resting muscles have no EMG activity so what is the muscle tone due to?
Viscoelastic properties.
73
What causes EMG activity?
The degree of activation of the contractile component of the muscle cells
74
What is thixotropy?
The reduction in viscosity of a fluid following movements. Like shaking a bottle of ketchup.
75
What happens to a thixotropic material when moved?
The more motion introduced to a thixotropic material, the less stiff it becomes.
76
Lake and robinson found what related to thixotropy?***
A 3X increase in thixotropic stiffening within 10 minutes of rest.
77
What causes thixotropy?
Change of viscosity between the sliding actin and myosin filaments they have a tendency to stick together.
78
What are some examples of thixotropy in muscle?
1) Warming up makes muscles less stiff 2) the high viscosity of resting muscle can help maintain posture without expending energy
79
What can cause hypertonic resting tones?
Shortening of elastic elements and can be due to increased EMG activity (spasm).
80
How is a digital pressure evaluation of muscle tone done and why?***
to see how easy it is to indent and how springy it is.
81
How should muscels be tested for muscle tone using range of motion test with end feel?***
Should be done at a constant rate to prevent a stretch reflex and to negate the thixotropic effect.
82
What is another test to test for muscle tone?***
Flapping test. (check if tissue is able to shake and move)
83
What is a primary disease of muscle? (3)
1) Muscular dystrophy 2) Fibromyositis 3) Primary fibromyalgia
84
What can cause DOMS (delayed onset muscle soreness)?***
Trauma leading to microtears)
85
What are different issues that can occur from trauma in muscles?
1) DOMS 2) Contusion/laceration pain 3) Strain pain (torn fibers)
86
What can cause muscle hypertonia?
Spasms, harbor trigger pints, contracture/scar tissue, fascial shortening, spastic UMN lesion.
87
What is the only thing that causes muscle hypertonia that is not painful?***
Fascial shortening.
88
What can cause muscle hypotonia?
Inhibited muscles, weak, neurological deficit.
89
What happens with loss of motor memory?
Loss of coordination/ speed of contraction.
90
What are hematoma and myositis ossificans?
Bony formation in a spot that was bruised.
91
What should not be done with bruises to prevent hematoma and myositis ossificans?
No trigger point therapy, no ultrasound, no heat, no aggressive stretchin.
92
What is a major site for muscle strains?
Musculotendinous junctions.
93
What is a grade 1 strain?
1) Minimal pain and splinting 2) minimal palpatory pain 3) Pain with muscle test, 4)some loss of range of motion
94
What is a grade 2 strain?
(partial tearing of the muscle, hemorrhage, marked pain, splinting) 1) same symptoms as grade 1 but more severe 2) pain and weakness with muscle teast 3) sometimes palpable defect
95
What is a grade 3 strain?
Severe strain (complete rupture) 1) marked loss of function 2) marked weakness with muscle test (often NO PAIN) 3) palpate torn muscle
96
What is the progression of fibrotic repair?
Fibrinous slurry > myofibrinosis (fiber formation in all directions) > to adhesions > contracture
97
What happens during fibrotic repair? (5)
1) Loss of elasticity, flexibility 2) Pain with contration and stretching 3) Decreased contractile strength 4) Decreased range of motion 4) Joint fixation
98
What type of occurance are muscle spasms?
Transient.
99
Are all muscle spasms painful?
No.
100
What causes pain with muscle spasms?
Local ischemia, increase load, possible shear effect between spasmed and non spasmed fibers.
101
Can contracture/ fascial shortening be painful?
May or may not be painful.
102
What happens to a muscle that is stretched for a long period of time?
It will relax and become weak.
103
What is a trigger point or myofascial pain syndrome?
A focus of hyperirritability in a tissue that, when compressed is locally tender and can give rise to referred pain
104
What causes trigger points?
1) Can be the result of injury 2) Can be due to muscle weakness
105
What is a contracture / fascial shortening?
Fixed shortening of a muscle due to fascial fibrosis or muscle fiber shortening
106
How is the resistance of contractures to stretching when relaxed?
There is a fixed high resistance and increased stiffness
107
Are contractures painful?
They can be both painful or non painful
108
What type of exercise will build stength, bulk, endurance, and enhance motion?
Isotonic.
109
What can cause inhibition weakness?
1) Injured joint/muscle 2) subluxation syndrome 3) MFTP 4) Overative antagonist (reciprical inhibition)
110
What does immobility/disuse of a muscle do? (3)
1) May atrophy (loss of width and length to some degree) 2) Sports-specific fibers are lost 3) Loss of strength or indurance
111
What happens to a muscle stretched for a long period of time?
It will relax and become weak.
112
What is a major cause of stretch weakness?
Postural strain
113
What is a lower motor neuron lesion?
one that affects the nerve root and/or peripheral nerve damage
114
What can accompany muscle weakness?
1) radiating pain into an extremity 2) sensory loss 3) decreased stretch reflex
115
Why does a loss of motor memory occur? (4)
1) To cope with injury for synergist substition (ie: shoulder hiking with rotator cuff strain) 2) new motor program 3) some muscles become relatively inactive (not necessarily weak) 4) coordination and speed of contraction is impaired
116
What are the 3 types of rehabilitation exercises?
Isometric exercise, isotonic exercise and isokinetic exercise
117
What is an isometric exercise used for?
For early activation of muscle (but will not reverse atrophy)
118
What is isotonic exercise used for?
Strength, bulk, endurance, enhance motion
119
What is isokinetic exercise used for?
stamina, maximum exercise throughout ROM.
120
What are the rehabilitative effects of adjusting? (3)
1) Trust may cause relaxation of segmental muscles 2) Re-establish segmental nerve supply 3) Adjust adjacenet extremity joints
121
Where is the nucleus pulposus located?
Centrally located ( a little posterior in lumbars)
122
How much water content is in the Nucleus pulposus and when is it the highest in a person's life?
Water content is 80-90% and highest at birth
123
Where in the spine is the size and ability to swell greatest in the Nucleus pulposus?
In the cervicals and lumbars
124
What is the IVD cross section like in the lumbars?
30-50%.
125
What is always happening to the Nucleus pulposus?***
There is always pre-stress.
126
What causes intradiscal pressure and why is this needed?
The ligamentum flavum (under elastic tension) and all the longitudinal ligaments create intradiscal pressure and stiffness to help support the spine
127
What are some characteristics caused the by the hydrostatic features of the nucleus pulposus?
1) allows uniform distribution of pressure throughout the disc 2) the disc stores energy (acts as a shock absorber 3) distributes load
128
What is the purpose of the nucleus pulposus?
Allows uniform distribution of pressure throughout the disc and stores enery and distributes loads.
129
IVD works kind of like what?
Cartilage in the hydraulic system.
130
What is the IVD made of?
Fibrocartilage.
131
What happens with compression of the IVD?
Expels the water and dampens the and re-distributes the load
132
Where are the annular fibers of the annulus fibrosis attached to?
Attached to the end plates of the inner zones by Sharpey Fiber's
133
Where are the adjacent lamina fibers of the annulus fibrosis situated?
Opposite directions to the annular fibers orientated at 120 degrees
134
What are the fiber orientation of the IVD compared to the disc plane? ***
They are angular degrees. (30 degrees)
135
Pessure in the nucleus puplosis is directed where?
Radially outward in all directions.
136
What load are IVDs best able to handle?
Compressive loads
137
What causes the stiffness in compression for IVDs?
High stiffness due to fluid pressure
138
Is the IVD more flexible at low or high loads?
Low loads
139
What is the function of the IVD being stiffer at high loads?
To shock absorb, dampen and stabilize
140
What is pressure in the nucleus pulposis due to?
Fluid pressure
141
With a compressive force directed on the nucleus pulposis where does the pressure and force become directed?
Directed radially outward in all directions
142
What is a Schmorl's node?
A bulging endplate that is due to a herniating nucleus pulposis into the vertebral body
143
Compression forces place what type of load on the annulus fibers? ***
Tensile.
144
What happens with the IVD with a compression load?
NP- bears most of the load and distrubutes the force as a tensile load to the annulus fibers.
145
In the morning the annular fibers have increased tensile loads from what?
The NP is full of fluid and creates a type of tensile stress on annular fibers.
146
Since the annular fibers have increased tensile loads in the morning they will be more susceptible to what type of injury?
Lifting injuries.
147
When will compression loads cause disc herniations?***
They wont not even if the load is enough to cause deformation because compression is harder on bone.
148
What actions create tensile and compressive stresses on the disk?
Flexion, extension and lateral bending
149
What stress does rotation produce on the disc?
Shear stress (and tensile stress on the disk)
150
What type of motion creates tensile stress on the posterior aspect of the IVD and why is this significant?
Flexion and this is the common place for disc herniations. (endplates have been found, not the disc)
151
What type of stretching should not be done in the mornings?
Flexion stretching.
152
Direction of herniation is in the same or opposite direction of the load? **
Opposite.
153
Forward flexion to the left can cause what type of disc herniation?
Posterior and to the right.
154
How common are anterior disc herniations?
Rare.
155
What type of loads cause the most injury to the disc?
Torsion.
156
What is torsion?
Shear, compression, tension.
157
What is the major cause of injury to the disc?
Torsion and flexion (even greater when combined)
158
Are shear injuries to the disc common?
No they are rare because a large load is needed for injury and the disc is stiff to these loads
159
What causes shear loads?
Torsion or rotation, flexion, improper lifting
160
Will there be more pressure on the discs with standing or sitting? ***
More with sitting, besides there was one study that says that sitting will create less pressure than standing.
161
Is there more load on the spine with supported sitting or unsupported sitting?
Unsupported sitting
162
What will increase disc pressure while sitting?
Slumping and even worse would be lifting something under your chair.
163
What will decrease disc pressure while sitting?
Backward inclination of the backrest.
164
What will create lower disc pressure laying down or the 90 90?
Laying down is 25 and 90 90 is 35.
165
How many times more load are dynamic loads than sitting static loads?
2 times
166
Where is shock absorption the greatest?
In the lumbars
167
What does the disc display when it absorbs shock?
It desplays histeresis
168
How does hysteresis increase?
With a larger load
169
What are the 2 general mechanisms for injuring a disc?
1. short duration HIGH AMPLITUDE. 2. LONG DURATION low magnitude. (failure is due to fatigue)
170
What plays a larger factor for injury of the disc, environmental loading or genetics?
Genetics probably plays a much larger factor than environmental loading.
171
What are the 2 most common problems seen with discs?
internal derangement, degeneration.
172
What part of the disc is innervated?
Outer anulus and not the nucleus pulposis.
173
What happens with tears in the disc?
New nerves and blood vessels grow in and now pain can be felt.
174
Tears in the disc first occur where?
In inner laminae.
175
Tears in the inner laminae of the disc are commonly a cause of what?
Low back pain and referred pain into the leg. **No nerve damage
176
Why will the tearing in the disc begin near the center?***
Peripheral attachment to vertebra is stronger than central.
177
With disc tearing where will damage be more likely to start near? ***
Near the nucleus pulposis.
178
Nucleus pulposis will migrate into fissures where?
Usually in a posterior direction.
179
What happens with a contained disc herniation? (3)
1) Disc material herniates into spinal 2) The nerve root is irritated/compressed 3) The NP material is NOT exposed
180
What happens with a non-noncontained disc herniation?
The NP material is exposed triggerin autoimmune response and increased severity
181
A 35 year old and a 65 year old would each probably have what disc problems?
35- disc herniation. 65- disc degeneration.
182
What occurs with disc degeneration? (5)
1) Proteoglycan is reduced in disc 2) Disc becomes less hydrated 3) disc is less elastic 4) cannot absorb shock or distribute loads as effectively 5) the disc is more susceptible to stress and injury
183
What happens with compression of a degenerated disc? (4)
1) disc dries out and losses hydrastatic "spring" 2) endplates have less pressure in center 3) outer annulus gets much more compression because the NP flattens out 4) annular fibers may bulge symmetrically into the canal because they are bearing more of the axial load
184
What are characteristics of the self sealing phenomenon?
1) 1st post injury loading curves differs from pre-injury curve 2) 3rd post-injury loading curve is similar to pre-injury curve 3) implies the presence of a mechanical reapir system
185
Spinal stability is provided by what 3 things?
1. Structural integrity of discs and ligaments. 2. Co-contraction of the stabilizing muscles. 3. Proper functioning motor contol system.
186
The motor control system is ____ dependent?
Loop.
187
What is the motor control loop system dependent on?
1) Uncorrupted information from transducers (mechanoreceptors in disc and liagaments and spindles in golgi tendon organs in muscles 2) Proper functioning software in the NS 3) Muscles that respond with proper timing, strength and endurance
188
What damage can lead to structural instability?
Damage to ligaments and disk
189
Muscles protect joints when?
When they are not at end range. They protect joints in the neutral zone.
190
The neutral zone is protected by what?
Fluctuating tone of low back and abdominal muscles.
191
Name the important lumbar stability muscle?
Transverse abdominus. (less important is the inernal obliques and mutlifidi)
192
When will the multifidus atrophy?
With chronic pain.
193
What is the multifidus impotant in?
Segmental stabilization.
194
When do the multifidi atrophy?
Atrophies post surgery, lumbar disc herniations and standard exercises may not reverse atrophy
195
Rotatoes primarily provide what?
Proprioceptive information.
196
What are 2 stabilizing strategies?
1) Muscle activity helps to stabilize the whole torso 2) Muscle activity directly helps to stabilize the spinal column itself
197
How is intra-abdominal pressure created?
By coordinated contraction of the diaphragm, abdominal and pelvic floor muscles
198
Intra-abdominal pressure converts the abdomen into what?***
Rigid cylinder that helps stabilize the spine.
199
What 2 things will contribute to the intra-abdominal pressure?***
Co-contaction of the trunk flexors and extensors.
200
When will the Intra-abdominal pressure increase?
lifting, lowering, running, jumping, unexpected perturbations.
201
What happens due to co contraction of intra abdominal muscles?
Co-contraction directly stabilizes the spinal column itself making it more rigid and less likely to buckle
202
What would happen if no co-contraction of the abdominal muscles occured?
The spine would be unstable when upright
203
The higher the load on the spine in a standing position the more active the ______.***
QL's.
204
The QL's are direct _____.
Low back stabilizers.
205
What activity will precede any sudden movement of the arm?
Transversus abdominis and diaphragm activity.
206
The first 50-60 degrees of flexion occurs where?***
In the lumbar spine.
207
Where will the last few degrees of flexion come from?***
By tilting of the pelvis and rotating forward at the hip.
208
How can tight hamstrings effect flexion?
It can make the flexion come from lumbars and the lumbar spine to bear more of the load.
209
Weak or inhibited G. max can cause what?
Increased load to lumbar spine during bending and lifting, shift of stress up to TFL during gait, and instability of the SI joint.
210
What are some causes of tight hamstings? ***
Overuse, sustained postures, weak rectus abdominus and inhibited gluteus maximus leading to instability in lumbar spine
211
What happens at full flexion?***
The superficial erector spinae become inactive, but the deep extensors and QL remain activated as we hang on our posterior ligaments.
212
What will protect the joints at end range?
Ligaments.
213
What happens with sustained flexion for 10 minutes?***
1. Superficial erector spinae relax. 2. Creep occurs in the viscoelastic tissues. 3. Random spasms in the multifidi. 4. effects of hystersis. 5. 50% of tissue recovery in about 10 minutes. 6. Hyperexcitability in the multifidus after standing up.
214
What is the problem with repetitive loading?
1)Muscles tire and spine lose some of its core stability 2) Repetitive end range loading creates elastic deformation (which does not recover immediately) and hysteresis (temporary loss of shock absorption with each cycle of loading)
215
What kind of stress does flexion create on posterior fibers?
Tensile stress
216
During flexion load on the ligaments what do the ligaments resist?
Shear load
217
How does maintaining lumbar lordosis is during bending protective?
Extensor muscles resist shear load
218
How long could it take to have full recovery of sustained flexion?
up to 48 hours.
219
What is the most common risk for disc injury?
Repetitive flexion.
220
During high or low cycles of end range can cause damage even in the elastic range.
High.
221
What activity modifications of flexion should be done?
avoid sustained flexion postures and avoid high repetitions (especially near end range).
222
When are loads on the facets greatest?
When the spine is hyperextended and stress on facet increases up to 30% of total load
223
Where can pain be coming from with hyperextension?
Not necessarily due to facet injury it could be coming from the disc.
224
Extension causes what type of load on the anterior fibers of the disc?
Tensile.
225
are anterior herniations common?
No they're rare
226
How are the the erector spinae muscles intensely activated?
by arching the back in prone position
227
What is recommended for early exercise in rehab cases to make the vertebrae more parallel?
Putting a cushion under the abdomen in a prone position
228
What is the order of stress from least to most with rotation?
1. Full range twisting. 2. High rotational torque in neutral. 3. High rotational torque through a full range of rotation.
229
Right hand vacuuming promotes what?
Left torsion.
230
The compressive load on the spine is the result of a combination of what? (4)
1) body weight, 2)the external load you are lifting, 3)how you are lifting it, 4) compression caused by the muscle contraction of the low back muscles.
231
What are the factors that affect how a person is lifting? (3)
1) The position of the object relative to the center of motion of the spine 2) the degree of flexion or rotation of the spine 3) the rate of loading
232
Holding an object close to the body reduces what?
The bending moment.
233
How does lever arm affect the load on the spine?***
The shorter the lever arm, the lower the load on the spine.
234
A higher lever moment means what?
More Newtons of force on the spine
235
What is the most important lifting advice?***
Keep the object close to the body.
236
What is harder to do lower or raise a load?
Lowering the stress involved can approach spinal tolerance.
237
What will create sacroiliac stability?***
The oblique dorsal muscle-fascia-tendon sling.
238
What is the oblique dorsal muscle-fascia-tendon sling made of?***
Latissimus dorsi, thoracolumbar fascia, and the contralateral gluteus maximus.
239
What type of stabilization will the oblique dorsal muscle-fascia-tendon sling provide for the SI joint?***
Force couple.
240
Conscious contraction of what muscle can help to stabilize the SI joint?***
Transverse abdominis.
241
What are peripheral nerves composed of?
1) Nerve fibers 2) connective tissue 3) blood vessels
242
What is the most direct impact to nerves?***
Blood loss it is even more than direct damage.
243
Where is epineurium found and what is its function?
Superficial and between fasciales and used to protect the nerve from external trauma, contains blood supply
244
Where is perineuriumfound and what is its function?
encases each fascicle and provides mechanical strength and a biochemical barrier
245
Where is endoneurium found and what is it made of?
Inside the fascicles and made up of fibroblasts and collagen
246
Is endoneural fluid pressure higher in the nerve or in the surround subcutaneous tissue?
Slightly higher in the nerve than the surround tissue
247
what causes the increase in fluid pressure? (3)
1) trauma and local edema 2)external compression 3) increased fluid pressure
248
Vessels pierce through the perineurium how?
At an oblique angle.
249
What does swelling do to the vessels in the perineurium?
It closes down the obliquely running vessel
250
What can injury a nerve?
Stretch (traction), compression, chemical (inflammation) or mechanical irritation
251
What type of injury can cause a stinger/ burner?
Stretch (traction).
252
What kind of deformation is plasticity?
Permanent.
253
At what % of strain on nerves does the plastic region begin?
Plastic range begins at about 20% strain
254
What are some characteristics of a nerve?
1) considerable tensile strength 2) can be lengthened with very little load 3) they are very elastic
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What is a tensile load like on the microcirculation? (3)
impaired venular flow at 8% of strain and all intraneual microcirculation ceased at 15%.
256
Where does tearing being in nerves?
In the endoneurial tubes
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At what percentage does complete failure of the nerve occur?
25-30%
258
What happens to the mechanical strength of previously injured nerves?
They may lose some of this mechanical strength
259
In the rabbit tibial nerve at what happened when 15% of strain was placed on it?
All intraneural microcirculation ceased
260
In the rabbit tibial nerve at what happened when 8% of strain was placed on it?
impaired venular flow at 8% of strain and all intraneual microcirculation ceased at 15%.
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In the rabbit what % of tensile load is needed to block neural flow?
12% followed by minimal recovery.
262
What is the ultimate tensile load on a human nerve root?
13-19%.
263
A SLR test will cause the nerve roots in the lumbar spine to move how much in the IVF?
2-5mm.
264
What is the purpose of orthopedic testing?
Testing the peripheral nerves by stretching them to reproduce symptoms and the reduction of tension on peripheral nerves or nerve roots may relieve symptoms
265
What is very susceptible to effects of compression especially in the bony window of the IVF?***
DRG.
266
What ganglion may be in the IVF?
Sensory DRG.
267
What part of a nerve will have less tissue protection?
The nerve root.
268
Since the nerve root has less tissue for protection what will this mean?
More sensitive to compression and irritation and more sensitive to ischemic changes than compression.
269
How was the pressure increased in the porcine model by Rydevik and Olmarker?***
pressure increased5mm Hg every 20 seconds.
270
What happened with 5-10 mm Hg on the nerve root?
Venous flow was stopped in some venules, retrograde stasis.
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What happened with 10 mm Hg pressure on the nerve root?
Transport of methylglucose to roots reduced 20-30%.
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What happened with 20-30 mm Hg pressure on PERIPHERAL NERVES?
axonal transport blocked.
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What happened with 50 mm Hg pressure on nerve roots for 2 minutes?
Causes entraneural edema, increased endoneurial fluid pressure, impaired capillary blood flow.
274
How long did the edema last with the 50 mm Hg pressure on the nerve roots for 2 minutes?
Lasts even after the comressive force is removed.
275
if the edema caused by the compression on nerve roots leads to fibrosis what happens?
A longer lasting effect
276
What does Fibrosis leads to within nerves?
Scars, and can cause increase endoneural fluid pressure and ischemia.
277
How does scarring due to fibrosis affect nerves?
Impair NR glide through IVF and can cause deformation and degeneration.
278
What happened with 50-75 mm Hg pressure on nerve roots for 2 hours?
Affects nerve conduction and incomplete recovery.
279
What happened with 100-200 mm Hg pressure on nerve roots for 2 minutes?
Pronounced nerve block and had a greater effect on recovery.
280
What does Compression do to nerves?
affects the ability of nerve function.
281
What is more damaging to nerve roots fast or slow onset of compression?***
Rapid onset is more damaging.
282
What will cause a more permanent change to nerves velocity or amplitude?***
Velocity is temporary and amplitude is permanent.
283
What happens at a site of injury in a nerve?
Action potential velocity and amplitude is reduced.
284
What is the pain like with acute nerve root compression?
Does not usually cause pain.
285
What will acute nerve root compression cause?
numbness, paresthesia and weakness.
286
What type of fibers are most susceptible to compression?
Larger fibers are more susceptible than smaller ones.
287
What causes radicular pain?
Minimal compression and irritation
288
What will make a nerve less likely to recover from damage?
The longer the duration of the pressure the more likely there will be irreversible damage.
289
What is the critical pressure level for peripheral nerves when functional changes occur?***
30 mm Hg. Due to vascular changes
290
Low levels of pressure for long periods can lead to what with peripheral nerves?
Scar formation.
291
what occurs at 80 mm Hg of pressure on a peripheral nerve?
axonal transport blocked.
292
what occurs at 30 mm Hg of pressure on a peripheral nerve?
complete ischemia
293
what occurs at 200-400 mm Hg of pressure on a peripheral nerve?
nerve fiber damage and rapid loss of function
294
When do radicular syndromes occur?
When the nerve root is compressed or irritated.
295
Is it damaging for 10 mm Hg at 2 sites than 50 mmHg at one site for the same amount of time?
Yes, two sites is more damaging
296
What takes up 35-50% of the IVF space?
The nerve root and its sheaths
297
what fills the rest of the IVF?
Connective and adipose tissue
298
What can reduce the IVF space? (5)
Scar tissue, osteophytes, stenosis, disc herniation or instability
299
What do motion of the neck affect?
The IVF and the central canal.
300
What happens to the IVF size with flexion, extension, ipsilateral rotation, contralateral rotation?***
Flexion- 31% increase. Extension- 20% decrease. Ipsi rotation- decrease. Contralateral rotation- increase.
301
What does cervical flexion do to the IVF size and nerve root?
It increases the IVF size but increases tension on the nerve root
302
What is a spinal cord injury known as?
Myelopathy.
303
What does cervical extension do to the IVF size spinal cord?
makes the cord shorter and fatter but also makes the canal smaller
304
What are some causes of central canal stenosis? (6)
1) Tumor (SOL) 2) Fracture 3) Instability 4) Instability 5) Adhesions/scar tissue 6) Infection
305
At what speeds do 80% of motor vehicle accidents occur?
At less than 25mph
306
In a typical rear end collision what are the common injuries in the cervical spine?
Hyperextension and hyperflexion
307
With a rear end impact what happens in the first 60 msecs?
The "S"curve = 1) the lower cervical spine is pushed forward by car seat momentum 2) the head momentarily remains behind 3) The spine assumes an S curve with the lower spine in segmental extension and upper spine in flexion
308
Is the "S" curve a physiologic motion?
No, not at all
309
In addition to the S curve what happens to the longitudinal aspect of the cervical spine?***
It causes axial compression
310
What does axial compression do to the stiffness of the spine?
Results in 50% decrease in stiffness of the cervical spine making it less able to resist flexion and extension forces
311
What is the "s" shaped curve?
1) Bending moment in flexion in upper cervicals 2) Bending moment in extension in the lower cervicals
312
At what segment is maximum extension found in the S shaped curve?
maxium extension is in c5-C6 motion unit
313
What happens due to the compressive load and shifting IAR at the bendming moment in relation to joints?
It is much more damaging to the joints (disc and facets)
314
in a rear end impact, what happens in the first 100 msecs?
1) The head catches up with the lower spine and there is 5x the force of gravity depending on the speed of the car and then ramping occurs as well
315
in a rear end impact, what happens in the first 150 msecs?
The entire spine goes into extension
316
What is ramping?
The head rolls backward over the head restraint
317
what is the muscle response for a rear end impact?
80, 125-215 msecs at which S curve load has already occurred but occurs before head hits the head restraint
318
What is an absolute contraindication to cervical manipulation after a whiplash accident?
Any signs of cerical cord trauma
319
With a rear impact what occurs with the occiput, C1 and C2?
They are loaded in flexion often resulting in joint restriction
320
What occurs in upper cervical injury (more common in high speed impacts)?
Injury to noci and mechanoreceptors that may account for balance disorders, dizziness, and perhaps mild traumatic brain injuries
321
What happens to musculature with a rear end impact? ***
Post structures are compressed and the anterior structures are torn (SCM, Scalenes, Longus Colli)
322
Can tensile loads tear the smooth muscle of the esophagus?
Yes, but these patients usually go to the ER
323
What can cause dysphagia after a MVA?
Mostly due to swelling in the anterior neck
324
can TMJ be an issue after MVA?
Yes, because it can drop the mandible and strain the anterior TMJ capsure although tmj symptoms are controversial
325
can the sympathetic chain be damaged from a MVA?
Yes
326
What happens if the deep flexors are damaged in a rear end impact MVA?
Results in instability (structural)
327
What happens if the superficial flexor muscles of the neck are damaged but the deep flexors are intact but weak?***
It causes a functional instability that can either causes persistent pain or increase susceptibility to future injury
328
What happens if there are sprains in the ALL?
If severe it can lead to structural instability
329
Which injury is the most common according to a cadaver study?
Disc and ALL tears
330
What is the typical lesion that occurs from the ALL injury?***
Avulsion of the disc from the end plate and tears of the annular fibers
331
What injury was found to be the most common at C4-C5 and C6-C7 in the cadaver study?***
Disc injuries
332
When are anterior fiber tears more common?
In rear end collisions
333
Are posterior disc herniations with nerve root compression common in MVA?
No they are not common.
334
What are rim lesions?
Linear clefts that run close and parallel to the end paltes in the peripheral part of the disc, near the rim get damaged
335
Where are rim lesions more common?
In the upper cervical region
336
where does healing of rim lesions occur?
Only in the outer 1/3
337
With which cervical motion can avulsion fractures occur and where do they occur?
Avulsion fractures may occur in lower corner of vertebral body
338
How does a facet capsular sprain occur?
Shear force and hyperextension places tensile load on the facet capsule
339
Why do facet capsular sprains affect people so much?
Facet joints are rich in nocireceptors
340
Where does facet compression occur more often?
Posteriorly in middle and lower cervicals
341
What can become intra-articular inclusion with facetal compression?
Meniscoids or synovial folds can become impinged
342
What causes 60% of the chronic pain in late whiplash?
Facet joints
343
What is not common in a rear-end collison?
Disc herniation
344
Can the nerve root be directly traumatized by the IVF?
Yes and it causes a radicular syndrome into the arm
345
What follows the phase of hyperextension in a rear end collision and what is it caused by??
Rebound hyperflexion follows hyperextension and it is caused by deceleration of the auto, impact of the seat and muscle stretch reflex
346
What nerve may be tractioned by hyperflexion and what does it lead to?
The greater occipital nerve may be tractioned causing a neurapraxis injury that contributes to headaches
347
What can hyperflexion do to the upper cervical nerve roots?
It can increase the tension on these nerve roots
348
Can MVA stretch the facet capsules leading to strain?
Yes , 29-35% have strains occur
349
What causes a deceleration injury?
Front end collisions
350
What happens in a deceleration injury? (4 steps)
1) The head rotates forward, forcibly flexing the neck 2) Followed by a degree of recoil resulting in hyperextension 3) The deceleration is first applied at CO-C1 then at C6 4) The neck will under go shear force
351
What are multiple plane injuries caused by? (4)
1) multiple impacts 2) postion of patient 3) tangential impacts 4) Patient's structural health
352
What are important details to find out about an acident in the history? (4)
1) Magnitude and direction of forces 2) postion and attitude of the body 3) force dampeners and augmenters 4) detailed list of symptoms and when they occurred including LOC
353
What are important to know about the magnitude and direction of the forces?
1) direction of impact 2) make and model of vehicles 3) vehicle speed 4) estimate of damage (body damage, drive away or tow, glove compartment fly open, objects fly from the back
354
What are important to know about the position and attitude of the body?
Which way is the body turned/ which way is the head turned?
355
What head position is the primary feature related to symptom persistence after a MVA
Rotated or laterally flexed head at time of impact
356
What happens to musclature if the head is rotated in a MVA?
More load on facets on facing side and more tearing in the opposite SCM
357
What are important to know about the force dampeners and accelerators?
1) Use of seat belt = dampener for body but augmenter for head and neck (3x more likely to cause injury) 2) Airbag (dampener) 3) brakes applied (augmenter for head and neck 4) damage to seat (dampener) 5) state of preparedness (unaware -> 15x higher risk for symptoms
358
What is the proper positioning of a head rest to decrease the amount of hyperextension?
Aligned with the EOP
359
Do head rests prevent the S curve ? ****
No because they can occur becore any of the muscle compensatory mechanisms occur.
360
Rank the immediate symptoms from most to least
Neck pain, headache, shoulder pain, back pain
361
What are the most injury resistant tissues in the neck ?
The muscles
362
Do muscles high frequency of healing?
They heal with high resiliency
363
What are the long term effects of chronic whiplast?
1) persistent facet syndromes (c5-C6, C2-3) 2) subluxations 3) joint instability (xrays may be negative for weeks)
364
How does one protect themselves in a rear end collison? (5) ****
1) Put your head and back against the seat 2) straight arm the steering well and get a good grip 3) If stopped, put your foot on the brake as hard as possible 4) look straight ahead and slightly up at the top of the windshield 5) scrunch your shoulders towards your ears to brace for impact
