Week 2 Flashcards
(302 cards)
1
Q
What is a lever?
A
Any rigid segment that rotates around a fulcrum
2
Q
When does a lever system exist?
A
Exists whenever two forces are applied to a lever in a way that produces opposing
torques
3
Q
What are the components of a lever system?
A
- Effort force (EF)
- Resistance Force (RF)
- Effort Arm (EA)
- Resistance Arm (RA)
4
Q
What is effort force?
A
Force that is producing the resultant torque(acting in the direction of rotation)
5
Q
What is resistance force?
A
Force creating an opposing torque
6
Q
What is the effort arm?
A
Moment arm for the effort force
7
Q
What is the resistance arm?
A
Moment arm for the resistance force
8
Q
The ___ force is always the winner in the torque game
A
The effort force is always the winner in the torque game
9
Q
The first class lever is where the axis lies somewhere between the ____ and the ___
A
The first class lever is where the axis lies somewhere between the point of application of the effort force and the point of application of the resistance force
10
Q
In the first class lever within the body, the effort arm may be ___ than the resistance arm as long as they are in ___ side of the axis
A
In the first class lever within the body, the effort arm may be equal to, greater, less than the resistance arm as long as they are in opposite side of the axis
11
Q
The second class lever system, is where the resistance force has a point of application between the ___ and ____
A
The second class lever system, is where the resistance force has a point of application between the axis and the point of application of the effort force
12
Q
In the second class lever system, the effort arm is always ___ the resistance arm
A
In the second class lever system, the effort arm is always greater than the resistance arm
13
Q
The second class lever system, is where the effort force has a point of application between the ___ and ____
A
The second class lever system, is where the effort force has a point of application between the axis and the point of application of the resistance force
14
Q
In the third class lever system, the effort arm is always ___ the resistance arm
A
In the third class lever system, the effort arm is always less than the resistance arm
15
Q
What is the mechanical advantage?
A
Measure of the mechanical efficiency of a lever system or the relative effectiveness of the effort force in comparison with the resistance force
16
Q
Mechanical advantage is related to the ___
A
Mechanical advantage is related to the classification of a lever
17
Q
Mechanical advantage provides an understanding of the relationship between the ___ and ___
A
Mechanical advantage provides an understanding of the relationship between the torque of an external force and the torque of a muscular force
18
Q
How is mechanical advantage calculated?
A
The ratio of the effort arm to the resistance arm
19
Q
What is the mechanical advantage when the effort arm is greater than the resistance arm?
A
It is greater than 1
20
Q
What happens when the mechanical advantage is greater than 1?
A
The magnitude of the effort force working through the larger moment arm can be smaller than the magnitude of the resistance force, yet still create greater torque
21
Q
What is the advantage of mechanical advantage?
A
A smaller force can defeat a larger force
22
Q
The mechanical advantage of a first class lever system in the body can be/is ___
A
The mechanical advantage of a first class lever system in the body can be/is greater than, less than, or equal to one
23
Q
The moment arm of the muscle in a first class lever system within the body is ___ to the moment arm of the external force
A
The moment arm of the muscle in a first class lever system within the body is shorter to the moment arm of the external force
24
Q
Muscles working at the first class lever system within the body tend to be at a ___
A
Muscles working at the first class lever system within the body tend to be at a mechanical disadvantage
25
The mechanical advantage of a second class lever system in the body can be/is ___
The mechanical advantage of a second class lever system in the body can be/is *greater than one*
26
The magnitude of the ___ can be, but is not necessarily less than the magnitude of the ____
The magnitude of the *effort* can be, but is not necessarily less than the magnitude of the *resistance*
27
The mechanical advantage of a third class lever system in the body can be/is ___
The mechanical advantage of a third class lever system in the body can be/is *less than one*
28
In the third-class lever system within the body, the effort arm is always ____ the resistance arm
In the third-class lever system within the body, the effort arm is always *less than* the resistance arm
29
The magnitude of the effort force must be ___ than the magnitude of the resistance force for the effort to produce greater torque
The magnitude of the effort force must be *greater* than the magnitude of the resistance force for the effort to produce greater torque
30
Why is a third-class lever system mechanically inefficient/working at a disadvantage?
The magnitude of the effort force must always be greater than the magnitude of the resistance force in order for the torque of the effort force to exceed the torque of the resistance force
31
What are the limitations of analysis of forces by lever systems?
- Discussion of lever systems ignored the established fact that the rotation of a lever requires at least one force couple
- Requires oversimplification that fails to take into consideration key elements that affect function and structural integrity
- Torques on human segments are not simply produced by muscles and external forces
32
True or false
An effort and resistance force are a force couple
False.
An effort and resistance force are not a force couple, because they move in opposite directions rather than the same
33
What are the 3 main methods of manipulating external forces to maximize torque?
- Torque of an external force can be increased by increasing the magnitude of the applied force
- Torque of an external force can be increased by applying the force perpendicular to the lever
- Torque of an external force can be increased by increasing the distance of the point of application of the force from the joint axis
34
A force applied to a lever produces its greater torque when the force is applied at ___ to the lever, presuming that there is a second part of the force couple
A force applied to a lever produces its greater torque when when the force is applied at *90 deg* to the lever presuming that there is a second part of the force couple
35
What are the components of total force?
- Perpendicular component
| - Parallel component
36
What is the perpendicular component of a total force?
The portion of a force that is applied at 90 deg to a segment
37
What is the parallel component of a total force?
The portion of a force that is applied at parallel to a segment
38
The parallel component of total force tends to create ___ motion
The parallel component of total force tends to create *translatory* motion
39
The perpendicular component of total force tends to create __ motion
The perpendicular component of total force tends to create *rotation and horizontal translation* motion
40
The sum of the magnitude of the perpendicular and parallel component of a force will always be ___ than the resultant force
The sum of the magnitude of the perpendicular and parallel component of a force will always be *greater* than the resultant force
41
The parallel component of most muscle forces contributes to ___, making muscles important joint stabilizers
The parallel component of most muscle forces contributes to *joint compression*, making muscles important joint stabilizers
42
Most of the force generated by a muscle contributes to joint compression rather than ___
Most of the force generated by a muscle contributes to joint compression rather than *joint rotation*
43
Rotation around a joint axis requires that the sum of the ____ equals zero
Rotation around a joint axis requires that the sum of the *parallel and perpendicular components* equals zero
44
What happens when the sum of the parallel or perpendicular components of a joint axis do not equal zero initially?
Translatory motion will continue to occur alone or in combination with rotatory motion until checked by a capsule ligamentous force or a joint reaction force
45
Majority of torque on a segment will be produced by forces or force components that are applied ___ to the segment and at some distance from the ___
Majority of torque on a segment will be produced by forces or force components that are applied *90 deg* to the segment and at some distance from the *joint axis*
46
The greater the net unbalanced torque, the greater the ___
The greater the net unbalanced torque, the greater the *angular acceleration of the segment*
47
What is an open chain activity?
One end of a segment or set of segments is free to move in space
48
What are the characteristics of an open chain activity?
- Independent motion
- Allows isolation
- Typically non-weight bearing
- Mobility is greater than stability
- More functional in the upper extremity than in the lower extremity
49
What is a closed chain activity?
Both ends of a segment or set of segments are constrained in some way and are not free to move in space
50
What are the characteristics of a closed chain activity?
- Interdependent motion
- Shared load
- Typically weight bearing
- Stability is greater than mobility
- More functional in the lower extremity than in the upper extremity
51
What is stress?
Resistance of a material to deformation
52
What is strain?
Deformation that occurs in a material in response to the application of an external load quantified as a percentage of change in some dimension of the material
53
What are the characteristics of an isotropic material?
* Homogenous
| * Exhibit uniform properties when loaded in different directions
54
What are the characteristics of an anisotropic material?
* Heterogenous
| * Exhibit non-uniform properties when loaded in different directions
55
What is load?
Application of a force, moment, or combination of them to a material
56
What is tension?
Equal and opposite loads applied away from the surface of a structure
57
What is compression?
Equal and opposite loads applied toward the surface of a structure
58
What is shear?
Opposing loads applied parallel to the surface of a structure
59
What is torsion?
Opposing loads are applied to the surface of a structure resulting in twisting about an internal axis
60
What is bending?
Combination of three or more loads applied to a structure causing it to bend about an axis external to itself
61
When does combined loading occur?
Combination of two or more loading modes applied to a structure at the same time
62
What is deformation?
Change occurring in some dimension of the
| material in response to an applied load
63
What is viscosity?
Ability of a material to resist flow and dampen shear forces
64
What is elasticity?
Ability of a material to return to its original shape following deformation after the removal of the deforming load
65
What allows meaningful movement of the human movement system to occur?
The articulations/joint of the skeletal system
66
What do human joints comprise?
Living tissues that change their structure to in response to changing environmental or functional demands
67
What are the 4 classes of connective tissue?
- Connective tissue proper
- Cartilage
- Bone
- Blood
68
____ are considered to be dense regular connective tissues
*Tendons and ligaments* are considered to be dense regular connective tissues
69
Connective tissue is characterized by...?
Widely dispersed cells and a large volume of extra-cellular matrix
70
___ is considered to be a highly specialized an mineralized form of connective tissue
*Bone* is considered to be a highly specialized an mineralized form of connective tissue
71
A microscopic levels, the extra-cellular matrix of connective tissues have both __ and ___ components
A microscopic levels, the extra-cellular matrix of connective tissues have both *inter-fibular and fibular* components
72
What determines the function of most connective tissue?
Extra -cellular components
73
The mechanical behavior of tissues involve the study of...?
The mechanical behavior of tissues involve the study of * how different materials and structures are able to provide support in response to changing forces*
74
The mechanical behavior of tissues deals with the relationship between ___ and ___
The mechanical behavior of tissues deals with the relationship between *stress and strain*
75
Stress occurs as a reaction force within...?
Stress occurs as a reaction force within *the substance of the structure in the presence of an applied load*
76
How can stress be quantified?
Force/unit area that develops within the material being tested.
77
What is ultimate stress?
The stress/load at the point of failure
78
What is ultimate strain?
The strain or deformation at the point of failure
79
What is isotropy?
A measure of the uniformity of the material when loaded from different directions
80
What is an example of an isotropic material?
Metals
81
What is an example of an anisotropic material?
Biological tissues
82
Which is more anisotropic: tendon, ligament, joint capsule, fascia?
Tendon more than ligament, joint capsule, and fascia
83
Tension results in...?
Tension results in *lengthening and narrowing of the structure and causes tensile stresses to occur within the structure*
84
What does compression result in?
Shortening and widening of the structure and causes compression stresses to occur within the structure
85
What does shear result in?
Internal angular deformation of the structure and causes shear stresses to occur within the structure
86
What does torsion cause?
A combination of compression, tension, and shear stresses to occur within the structure
87
What does combined loading cause?
Multiple combinations of stresses to occur within the structure
88
What is a load deformation curve?
A graph utilized to determine the strength properties and materials in which the load applied is plotted against the deformation material
89
What type of information does a load deformation curve provide?
Elasticity, plasticity, ultimate strength and stiffness, failure point, and the amount of energy prior to failure
90
What does the toe region of the load deformation curve signify?
Signifies the removal of slack within the structure as the tensile load is applied
91
What is a crimp?
A wavy configuration of collagen fibers found in most relaxed connective tissue
92
When does a crimp disappear?
When the collagen fibers in connective tissue are loaded
93
Where in the load deformation curve does a crimp occur?
In the toe region
94
What does the elastic region on the load deformation curve represent?
The range in which the stress is directly proportional to the strain
95
All the deformation occurring in the elastic region is ___
All the deformation occurring in the elastic region is *reversible*
96
Is the structure in the elastic region able to return to its normal dimensions after the load has been removed?
Yes, structures in the elastic region are able to return to its normal dimensions after the load has been removed
97
What does the elastic limit/ yield point signify?
The end of the elastic region where the material begins to undergo permanent deformation
98
What does the plastic region on the load deformation curve represent?
The range in which materials begin to deform at a rate disproportional to the stress
99
What is occurring in the plastic region?
Permanent deformation, although the structure is still intact and it may return to similar dimension with time
100
What does the ultimate failure point represent on the deformation curve?
Represents the continued load in the plastic range, but the maximum load that the tissue can tolerate has been reached.
101
What is happening with deformation and load at the ultimate failure point?
Deformation continues until it fails and load equals failure load
102
True or false
Tissue size can affect response to loading
True
103
Increased cross-sectional area of a tissue means that the tissue can withstand ___ force at any given length
Increased cross-sectional area of a tissue means that the tissue can withstand *more* force at any given length
104
An increased cross-sectional area of a tissue leads to ___
Greater strength and stiffness
105
Does the elongation to failure and length of a tissue changes when the cross sectional area is increased?
No, it stays the same
106
What does an increased tissue length mean?
It means that it can elongate further under the same load of condition as a shorter tissue
107
What is the status of strength and stiffness when the tissue length has been increased?
- Strength is the same
| - Stiffness is reduced
108
What is young's modulus/modulus of elasticity?
The linear portion of the curve that occurs in the elastic region of the load deformation curve.
109
The ____ is the measure of stiffness or resistance to external loads
The modulus of elasticity is the measure of stiffness or resistance to external loads
110
The _____ is the measure of compliance to external load
The reverse of the modulus of elasticity is the measure of compliance to external load
111
What does it mean when the slope through the young modulus is steep?
The modulus of elasticity is said to be high
112
A high modulus of elasticity correlates with ___?
A high modulus of elasticity correlates with *high stiffness, and low compliance*
Ex: cortico tissue
113
What does it mean when the slope through the young modulus is gradual?
The modulus of elasticity is said to be low
114
A low modulus of elasticity correlates with ___?
A low modulus of elasticity correlates with *low stiffness and high compliance*
Ex: Adipose tissue*
115
What is the stress-strain curve?
Load-deformation curve in which load is expressed as load per unit area and strain is expressed as deformation per unit of length or percentage of deformation
116
What happens in the toe region of the stress-strain curve for collagenous materials?
There is very little force to deform tissue in straightening crimp
117
What happens in the elastic region of the stress-strain curve for collagenous materials?
Collagen fibrils are being stretched and are resisting applied force
118
____ reflects type of collagen, fibril size, and cross-linking among collagen molecules
*The elastic region of the stress-strain curve for collagenous materials* reflects type of collagen, fibril size, and cross-linking among collagen molecules
119
What happens when load is removed in the elastic region of the stress-strain curve for collagenous materials?
When the load is removed, structure will return to its pre-stressed dimensions, although this return will take some time
120
The level of loading in the elastic region of the stress-strain curve for collagenous materials includes ____ and typically extends to about ____
The level of loading in the elastic region of the stress-strain curve for collagenous materials includes *stresses and strains that
occur with normal activities and typically extends to about 4% strain*
121
What happens in the plastic region of the stress-strain curve for collagenous materials?
Micro failure of collagen fibers begins and structure no longer capable of returning to original length after force removed
122
What does the recovery in the plastic region of the stress-strain curve for collagenous materials require?
Recovery after this level of loading requires considerable time as it involves aspects of healing
123
What are the aspects of healing in the plastic region of the stress-strain curve for collagenous materials require?
* Synthesis of new tissue
| * Cross-linking of collagen molecules
124
What happens in the beyond ultimate failure point of the stress-strain curve for collagenous materials?
Remaining collagen fibrils experience increased stress and rapidly rupture sequentially
125
What is created in the beyond ultimate failure point of the stress-strain curve for collagenous materials?
Overt failure of the tissue
126
What type of tissue failure is created in the beyond ultimate failure point of the stress-strain curve for collagenous materials?
- Rupture
- Avulsion
- Fracture
127
What is a rupture?
Failure through middle of ligament or tendon
128
What is an avulsion?
Failure at bony attachment of ligament or tendon
129
What is a fracture?
Failure within bony tissue
130
A rupture is typically a response of ___
A rupture is typically a response of a *fast loading rate*
131
An avulsion is typically a response of ___
An avulsion is typically a response of *a slow loading rate*
132
Deformation prior to failure in the beyond ultimate failure point of the stress-strain curve for collagenous materials varies on?
- Tissue type
| - Tissue size
133
What is viscoelasticity?
A characteristic exhibited by all tissues
of the body in which the properties of
viscosity and elasticity are combined
134
Viscoelasticity makes tissue behavior ___ dependent
Viscoelasticity *makes tissue behavior time-, rate-, and history-dependent*
135
What is creep?
Progressive strain or deformation of a structure under the influence of a constant stress or load
136
What are the determinants of mechanical properties of a fibrous connective tissue?
* Size and density of the structure
* Mechanical properties of the collagen and elastin fibers contained in the structure
* Proportion of collagen and elastin fibers
* Orientation of fibers in the tissue
137
What are the time dependent properties illustrated by the viscoelasticity of connective tissue?
- Creep
- Hysteresis
- Stress-relaxation
138
How does creep apply in the clinic?
Stretching shortened tissue
139
How is creep tested in cartilage and bone and why?
Compressive loading.
So that the depth of indentation represents creep and covering
140
What is stress-relaxation?
Decrease in the stress within a structure in the presence of a constant strain or deformation
141
What happens if a tissue stretched to a fixed length, while the force required to maintain the length is measured?
The force needed will be decreased over time
142
When does hysteresis occur?
When the force and length are measured as forces are loaded and unloaded and the resulting load deformation curves do not follow the same path
143
In hysteresis, energy is often lost as ___
In hysteresis, energy is often lost as *heat*
144
What are the rate dependent properties illustrated by the viscoelasticity of connective tissue?
Strain-rate sensitivity
145
What is strain-rate sensitivity?
Resistance to deformation relative to rate of load application
146
Increased rate of load application is associated with ___
Increased rate of load application is associated with *increased resistance to deformation*
147
Decreased rate of load application is associated with ___
Decreased rate of load application is associated with *Decreased resistance to deformation*
148
Less deformation prior to failure occurs with ____
Less deformation prior to failure occurs with *load application at a higher rate for a brief duration*
149
What are the mechanical properties of fibrous connective tissue?
- High tensile strength
- Anisotropic
- Fails at strains as low as 9% for structures with little or no elastin fiber content
- Fails at strains of up to 70% for structures with high elastin content
150
What are some of the mechanical properties of fibrous connective tissue?
- Ultimate load and strain increase with increasing speed of loading
- Stiffness does not change with changes in speed of loading
- Significant viscoelastic characteristics, especially in first 6-8 hours of loading
- Compared to tendons, ligaments must withstand forces in all directions
151
In the clinic, the viscoelastic characteristics of fibrous connective tissue can be exploited for ___
In the clinic, the viscoelastic characteristics of fibrous connective tissue can be exploited for *increasing tissue length without tearing or failure*
152
What can fatigue type failures result from in a fibrous connective tissue?
Fatigue type failures can result from exposure to loads that are too high, too numerous, or too frequent with management requiring a reduction in one or more of these variables
153
___ results in a general loss of collagen content, but an increase in collagen cross-linking
*Aging* results in a general loss of collagen content, but an increase in collagen cross-linking
154
The use of NSAIDs can cause an/a ___ in the tensile strength of connective tissues due to an increase in overall collagen content and in the proportion of non-soluble collagen
The use of NSAIDs can cause an *increase* in the tensile strength of connective tissues due to an increase in overall collagen content and in the proportion of non-soluble collagen
155
The final trimester of pregnancy is accompanied by a significant release of the hormone relaxin resulting in a ____ making the tissues more susceptible to injury
The final trimester of pregnancy is accompanied by a significant release of the hormone relaxin resulting in a *general loss of stiffness and strength of the connective tissues* making the tissues more susceptible to injury
156
What are the determinants in the mechanical properties of cartilage?
* Type of cartilage (i.e. hyaline cartilage, fibrocartilage, elastic cartilage)
* Structural composition (i.e. Type I vs. Type II collagen)
* Proportions of structural components (i.e. water, collagen, elastin, proteoglycans)
157
What is the boundary mechanism in the lubrication of cartilage?
Monolayer of glycoproteins carries load and provides separation of cartilage surfaces for lubrication
158
What is the fluid film mechanism in the lubrication of cartilage?
Fluid pressure provides separation of articular surfaces and, thus, provides lubrication
159
What are the mechanical properties of cartilage?
- Anisotropic
- Biphasic
- Capable of large viscoelastic deformation due to processes of fluid exudation and redistribution
160
What does biphasic mean?
When something has both fluid and solid phases
161
Cartilage depends upon ____ through its substance via cyclic compression and decompression as well as motion
Cartilage depends upon *diffusion and the pumping of fluids* through its substance via cyclic compression and decompression as well as motion
162
Compromise of cartilage health should be expected following ____ due to an alteration in nutritional supply mechanisms
Compromise of cartilage health should be expected following *immobilization* due to an alteration in nutritional supply mechanisms
163
Injury of cartilage can often occur without ___ and can progress until ___ is quite advanced before pain is experienced
Injury of cartilage can often occur without *initial awareness* and can progress until *tissue destruction* is quite advanced before pain is experienced
164
What are the determinants of the mechanical property of bone?
* Size, density, and geometric characteristics of bone specimen
* Mode of loading applied
* Rate and frequency of loading
165
What does the type of mechanical property of a bone depend upon?
The type of bone in consideration
166
What are the two types of bone?
- Cortical (compact) bone
| - Cancellous (trabecular or spongy) bone
167
What are the mechanical properties of cortical (compact bone)?
* Very high ultimate strength in compression and tension
* Very high stiffness
* Anisotropic
* Fractures at approximately 2% strain
* Stiffness and ultimate load increase with increased speed of loading
168
What are the mechanical properties of cancellous (trabecular or spongy) bone?
• Moderate to low ultimate strength depending upon porosity
• Moderate to low stiffness
• Anisotropic
• Typically fractures at approximately 7%
strain, but can sustain strains as high as
75% before failure in some instances
• Stiffness and ultimate load tolerance increase with increased speed of loading
169
Changes in the mechanical properties of
| bone generally parallel changes in ___
Changes in the mechanical properties of
bone generally parallel changes in *bone
mass, aging and osteoporosis*
170
Stresses on bone are due to ____
Stresses on bone are due to *weight bearing
| and muscle loading*
171
____ can considerably modify the exposure of bones to loading, but become less effective in doing so with fatigue
*Muscles* can considerably modify the
exposure of bones to loading, but become
less effective in doing so with fatigue
172
Bone is subject to stress (fatigue) fracture relative to ____of loading
Bone is subject to stress (fatigue) fracture relative to *magnitude, quantity, and
frequency of loading*
173
When does the bone being subject to stress (fatigue) fracture relative to magnitude, quantity, and frequency of loading occur?
Occurs with shift in balance of bone
| formation and absorption toward osteoclastic activity
174
What does the management of bone being subject to stress (fatigue) fracture relative to magnitude, quantity, and frequency of loading require?
Management requires the modification of
| one or more of the contributing factors
175
Taking advantage of the mechanical advantage of _____, a dynamic splint can be used to aide in increasing joint ROM
Taking advantage of the mechanical advantage of *creep*, a dynamic splint can be used to aide in increasing joint ROM
176
What is a dynamic splint?
A spring loaded tensioning device that provides for the application of low load, long duration stretch.
177
What does the dynamic splint mechanism provide?
A constant tensioning force to be applied,, while linked changes occur in the tissues
178
____ uses elastic components
*Dynamic splints* uses elastic components
179
____ uses inelastic components to apply torque to a joint in order to statically position it as close to the end of ROM as possible.
*Static progressive splinting* uses inelastic components to apply torque to a joint in order to statically position it as close to the end of ROM as possible.
180
What mechanical advantage does a static progressive splint take advantage of?
Stress- relaxation
181
Skeletal muscle function provides both __ and ____
Skeletal muscle function provides both *mobility and stability*
182
Skeletal muscle can produce or control movement of the ___ around the joint axis, where they can resist extraneous movement of joint surfaces through the ___
Skeletal muscle can produce or control movement of the *bony lever* around the joint axis, where they can resist extraneous of joint surfaces through the *approximation of joints*
183
The total muscle force vector can be approximated by...?
The total muscle force vector can be approximated by *putting the point of application at the muscle's attachment and then drawing an action line symmetrically towards the middle of the muscle's fibers*
184
The direction of pull of any muscle is always towards the ____ of the muscle
The direction of pull of any muscle is always towards the *center* of the muscle
185
What are the determinants of muscle force production?
- Recruitment of motor units
- Muscle fiber type
- Muscle length
- Speed of contraction
- Muscle Action
- Torque Potential
- Muscle architecture
186
____ is fundamental to the recruitment of motor units
*Size principle* is fundamental to the recruitment of motor units
187
Which motor units are recruited 1st?
Motor units with small cell bodies and few motor fibers
188
What are the other factors influencing motor unit recruitment?
- Nature of task performed
- Variable within individual muscles of synergistic group
- Firing frequency
- Fatigue
189
Small distal muscles rely on ____
Small distal muscles rely on *increased frequency of firing*
190
Large proximal muscles rely on ___
Large proximal muscles rely on *the recruitment of additional motor units*
191
____ can also affect force production during muscle contraction
*muscle fiber types* can also affect force production during muscle contraction
192
Muscle fiber types is reflective of the ___
Muscle fiber types is reflective of the *physiologic characteristics of muscle fibers*
193
The physiologic characteristic of muscle fibers can affect the ____
The physiologic characteristic of muscle fibers can affect the *potential speed of contraction, the potential magnitude of force generation, and determines the fatigueability of the muscle fiber*
194
What are the characteristics of type 1 slow oxidative fibers?
- Diameter: Small
- Color: Red
- Capillarity: Dense
- Myoglobin content: High
- Speed of contraction: Slow
- Rate of fatigue: Slow
195
What are the characteristics of type 2a fast oxidative glycolitic fibers?
- Diameter: Intermediate
- Color: Red
- Capillarity: Dense
- Myoglobin content: Intermediate
- Speed of contraction: Fast
- Rate of fatigue: Intermediate
196
What are the characteristics of type 2x fast glycolitic fibers?
- Diameter: Large
- Color: White
- Capillarity: Sparse
- Myoglobin content: Low
- Speed of contraction: Fast
- Rate of fatigue: Fast
197
What is muscle tension?
Ability to develop tension and to exert a force on the bony lever is most important characteristic of muscle
198
Total tension in a muscle includes both ___ and ____ components
Total tension in a muscle includes both *active and passive* components
199
Total tension is a vector quantity possessing magnitude, ____, an ___, and a direction of pull
Total tension is a vector quantity possessing magnitude, *two points of application,* an *action line*, and a direction of pull
200
____ tension is developed in the parallel elastic component of the muscle.
*Passive* tension is developed in the parallel elastic component of the muscle.
201
Passive tension may add to the ____ produced by the muscle when the muscle is lengthened
Passive tension may add to the *active tension* produced by the muscle when the muscle is lengthened
202
Passive tension may become slack and not produced to the total tension when the muscle is _____
Passive tension may become slack and not produced to the total tension when the muscle is *shortened*
203
Passive tension is create by___
Passive tension is create by *lengthening the muscle beyond slack length of the tissues*
204
Active tension refers to the tension developed by ___
Active tension refers to the tension developed by *the contractile elements of the muscle*
205
Active tension is initiated by ____
Active tension is initiated by *cross bridge formation and movement of thick and thin filaments*
206
The amount of active tension that a muscle can generate depends on ___
The amount of active tension that a muscle can generate depends on *neural factors and mechanical properties of muscle fibers*
207
What are the neural factors included in the amount of active tension that a muscle can generate?
- Frequency of motor units firing
- Number of motor units firing
- Size of motor units firing
208
What are the mechanical properties included in the amount of active tension that a muscle can generate?
- Isometric length tension relationship
| - Force velocity relationship
209
A direct relationship exist between the isometric tension development in a muscle fiber and the ____
A direct relationship exist between the isometric tension development in a muscle fiber and the *length of the sarcomeres of the muscle fiber*
210
When does an optimal sarcomere length exist?
When a muscle fiber is capable of developing maximal isometric tension.
211
Why does a muscle fiber obtain maximal isometric tension at an optimal sarcomere length?
Because thick and thin filaments are positioned so that maximum number of cross bridges within the sarcomere can be formed.
212
What happens if the muscle fibers is shortened or lengthened beyond optimal length?
The amount of active tension that a muscle fiber is able to generate when stimulated decreases
213
Sarcomere length-tension relationship only applies to ___
Sarcomere length-tension relationship only applies to *isometric muscle contraction*
214
During dynamic contractions, length-tension relationship must be combined with ____ to determine the effect that both length and velocity have on muscle tension
During dynamic contractions, length-tension relationship must be combined with *force-velocity relationship* to determine the effect
that both length and velocity have on muscle tension
215
Force-velocity relationship describes relationship between ___ and ___
Force-velocity relationship describes relationship between velocity of muscle contraction and force produced
216
Force-velocity relationship provides an explanation for what happens during ___ and ___ muscle contractions
Force-velocity relationship provides an explanation for what happens during *concentric and eccentric* muscle contractions
217
What is the speed of shortening?
The rate at which myo-filaments are able to slide pass one another to be able to form and reform cross bridges
218
Speed of shortening is related to ___ and ___
Speed of shortening is related to *muscle fiber type and length*
219
As load increases on a muscle, concentric contraction velocity ___ at isometric maximum
As load increases on a muscle, concentric contraction velocity *slows to zero* at isometric maximum
220
In concentric muscle contraction, as the shortening speed decreases, the tension in muscle ___
In concentric muscle contraction, as the shortening speed decreases, the tension in muscle *increases*
221
In isometric muscle contraction, the speed of shortening is ___ and tension is ___ than in a concentric contraction
In isometric muscle contraction, the speed of shortening is *zero* and tension is *greater* than in a concentric contraction
222
In an eccentric contraction, as the speed of muscle lengthening increases, the tension in the muscle ___ and then ____
In an eccentric contraction, as the speed of muscle lengthening increases, the tension in the muscle *increases and then plateaus*
223
____ contraction occurs with the active shortening of a muscle
*Concentric* contraction occurs with the active shortening of a muscle
224
Concentric contraction involves sliding of the ___
Concentric contraction involves sliding of the *thin filaments toward and past the thick filaments*
225
Concentric contraction is accompanied by the ___ and results in ___
Concentric contraction is accompanied by the *formation and reformation of cross bridges in each sarcomere* and results in *shortening of the muscle and the generation of tension*
226
A ____ contraction is one in which muscle fibers do not change
An *isometric* contraction is one in which muscle fibers do not change
227
What muscle action is happening when the whole muscle is activated and bones to which it is attached to do not move?
Isometric contraction
228
During a concentric contraction, bones move ____
During a concentric contraction, bones move *closer together as the whole muscle shortens*
229
During an eccentric contraction, bones move ____ as the muscle tries to control descent of the weight and the muscle ____ as the joint moves through the ROM
During an eccentric contraction, bones move *away from each other* as the muscle tries to control descent of the weight and the muscle *lengthens* as the joint moves through the ROM
230
Amount of tension that can be developed in a muscle varies according to ___
Amount of tension that can be developed in a muscle varies according to *type of contraction*
231
In which contraction is tension the greatest in general?
Eccentric contraction
232
What are the factors affecting torque potential?
- Length of moment arm of muscle force
- Length of the muscle
- Velocity of shortening or lengthening during dynamic movements
233
Muscles produce force in the body by acting over a ___ at the joint to produce a torque
Muscles produce force in the body by acting over a *moment arm* at the joint to produce a torque
234
Moment arm of the muscle can change with ____ which affects the torque being produced
Moment arm of the muscle can change with *joint position* which affects the torque being produced
235
Single joint muscles tend to be recruited to produce force primarily in ____ contractions
Single joint muscles tend to be recruited to produce force primarily in *concentric and isometric* contractions
236
Multi joint muscles tend to be recruited to control the fine regulation of torque during dynamic movements involving ___ more than ___ muscle actions
Multi joint muscles tend to be recruited to control the fine regulation of torque during dynamic movements involving *eccentric more than concentric* muscle actions
237
Multi joint muscles tend to be recruited during more ___ motions requiring movements along multiple axis
Multi joint muscles tend to be recruited during more *complex* motions requiring movements along multiple axis
238
____ is a phenomenon related to muscle length- tension relationship and the multi joint nature of some muscles
*Active insufficiency* is a phenomenon related to muscle length- tension relationship and the multi joint nature of some muscles
239
What is active in sufficiency?
Reduced capacity in production of active tension across one joint occurring when muscles are placed on slack across another joint
240
When does passive insufficiency occur?
Occurs when an inactive, potentially antagonistic muscle is of insufficient length to permit full ROM at the joints crossed by the passive muscle
241
___ can measure the electrical activity of a muscle
*EMG* can measure the electrical activity of a muscle
242
The electrical activity of a muscle is directly proportional to the ___
The electrical activity of a muscle is directly proportional to the *motor unit activity*
243
The motor unit activity of a muscle is directly proportional to the __
The motor unit activity of a muscle is directly proportional to the *isometric muscle force*
244
The type and direction of motion that results from an active muscle contraction depends on ___
The type and direction of motion that results from an active muscle contraction depends on *the net force and torques acting on each of the bony attachments*
245
Muscle will move a segment in its direction of pull only when ___
Muscle will move a segment in its direction of pull only when *the torque generated by the muscle exceeds opposing torques*
246
What are the advantages of isokinetic exercise and testing?
* Maximal loading through ROM
* Safe
* Objective
* Reproducible measurement
247
What are the disadvantages of isokinetic exercise and testing?
* Isolation
* Non-weight bearing
* Limited acceleration
* Mono-planer
* Cost
* Not functional
* Differences in exertion by performer
248
___ is the basic functional unit of the nervous system
A *neuron* is the basic functional unit of the nervous system
249
The ___ is the neuron cell body
The *perikaryon* is the neuron cell body
250
____ is housed in ventral horn of spinal cord (motor at all levels, pre-ganglionic autonomic in levels T1 through L3), sympathetic trunk (postganglionic autonomic), and dorsal root ganglia (sensory)
*Perikaryon* is housed in ventral horn of spinal cord (motor at all levels, pre-ganglionic autonomic in levels T1 through L3), sympathetic trunk (postganglionic autonomic), and dorsal root ganglia (sensory)
251
___ are typically, a single fiber extending away from cell body with branches near
termination
*Axons* are typically, a single fiber extending away from cell body with branches near termination
252
The conduction speed of an axon increases with ___
The conduction speed of an axon increases with *myelination*
253
The conduction speed of an axon is positively correlated with ____
The conduction speed of an axon is positively correlated with *fiber diameter*
254
___ are branched structures from cell body and terminal axon that act to increase the number of available synapses, the surrounding
*Dendrites* are branched structures from cell body and terminal axon that act to increase the number of available synapses
255
The number of available synapses is further increased by the presence of ___ upon surface of dendrites
The number of available synapses is further increased by the presence of *dendritic spines* upon surface of dendrites
256
What are the gross structures of the nervous system?
- Brain
- Spinal cord
- Nerve roots
257
The brain is housed entirely within the ___
The brain is housed entirely within the *cranium*
258
___ is structured as a continuation of the medulla oblongata from foramen magnum, terminates at the conus medullaris at L2 level
*Spinal cord* is structured as a continuation of the medulla oblongata from foramen magnum, terminates at the conus medullaris at L2 level
259
The spinal cord attaches to the coccyx via ___
The spinal cord attaches to the coccyx via *filum terminale*
260
___ are transitional structure from central nervous system into peripheral nervous system
*Nerve roots* are transitional structure from central nervous system into peripheral nervous system
261
____ is a delicate and continuous layer of connective tissue meshwork surrounding all elements of the central nervous system
*Pia mater* is a delicate and continuous layer of connective tissue meshwork surrounding all elements of the central nervous system
262
___ is a delicate connective tissue meshwork housing cerebrospinal fluid between itself and pia mater. It connects into pia mater via arachnoid trabeculae
*Arachnoid mater* is a delicate connective tissue meshwork housing cerebrospinal fluid between itself and pia mater. It connects into pia mater via arachnoid trabeculae
263
____ is a tough outermost meningeal layer with high collagen content aligned in layers longitudinally. It is highly vascularized and innervated
*Dura mater* is a tough outermost meningeal layer with high collagen content aligned in layers longitudinally. It is highly vascularized and innervated
264
What is the structural hierarchy of the PNS?
- Nerve fiber
- Fascicle
- Peripheral nerve trunk
265
____ axons housed within collagenous basement membrane and is surrounded by innermost connective tissue layer referred to as the endoneurium
*Nerve fiber* axons housed within collagenous basement membrane and is surrounded by innermost connective tissue layer referred to as the endoneurium
266
____ are bundles of nerve fibers that are surrounded by external epineurium
*Fascicles* are bundles of nerve fibers that are surrounded by external epineurium
267
Fascicles are separated by an ___
Fascicles are separated by an *internal epineurium*
268
Each fascicle is intimately surrounded by a connective tissue layer called ____
Each fascicle is intimately surrounded by a connective tissue layer called *perineurium*
269
Peripheral nerve trunk are bundle of fasciculi, enveloped by loose areolar tissue layer termed _____
Peripheral nerve trunk are bundle of fasciculi, enveloped by loose areolar tissue layer termed *mesoneurium*
270
The nervous system is highly integrated by ___
The nervous system is highly integrated by *connective tissue*
271
___ is the supporting cells between neurons of the nervous system and is involved in the myelination process
*Neuroglia* is the supporting cells between neurons of the nervous system and is involved in the myelination process
272
____ is the oligodendroglia of the central nervous system and the schwann's cells of the peripheral nervous system
*Neuroglia* is the oligodendroglia of the central nervous system and the schwann's cells of the peripheral nervous system
273
What are the connective tissue structures of the nervous system?
- Neuroglia
- Meninges
- Peripheral connective tissues
274
____ and ___ allow stretch and compression without kinking
Pia mater and arachnoid mater allow stretch and compression without kinking
275
____ provides tremendous axial loading strength as well as relative structural stability through osseus attachments
*Dura mater* provides tremendous axial loading strength as well as relative structural stability through osseus attachments
276
Peripheral connective tissues provide ____ as well as ____ to tensile and compressive forces
Peripheral connective tissues provide *protection as well as resistance* to tensile and compressive forces
277
What are the functions of connective tissue within the nervous system?
- Adds both tensile strength and elasticity to nervous tissue where movement is necessary
- Adds structural stability through attachments to adjacent structures
- Facilitates processes involved in nutrition, oxygenation, and waste removal (i.e. circulation)
- Influences interactions with endocrine and immune systems
- Highly innervated and nociceptive although nervous tissue itself is not
278
20% of the oxygen available in circulating blood utilized by the _____, which is 2% of body mass
20% of the oxygen available in circulating blood utilized by the *nervous system,* which is 2% of body mass
279
Both central and peripheral components of the nervous system have extensive intrinsic ___ supported by ____
Both central and peripheral components of the nervous system have extensive intrinsic *vascular systems supported by connective tissues*
280
The nervous system integration with the vascular system is susceptible to ____ and ____ which can alter blood flow
The nervous system integration with the vascular system is susceptible to *mechanical compression and tensions forces* which can alter blood flow
281
The vascular system within the nervous system are ___ innervated and nociceptive although nervous tissue itself is not
The vascular system within the nervous system are *highly* innervated and nociceptive although nervous tissue itself is not
282
What are the ways that the nervous system tissues is considered to be continuous throughout the body?
- Mechanical
- Electrical
- Chemical
283
How is the nervous system tissue continuous throughout the body mechanically?
Continuous via connective tissue associations
284
How is the nervous system tissue continuous throughout the body electrically?
Interconnected electrically via impulse generation and transmission
285
How is the nervous system tissue continuous throughout the body chemically?
Linked chemically via flow of neurotransmitters
286
What are the functions of the nervous system?
- Conducts and regulates impulses via continuous electrochemical antegrade and retrograde flow
- Associates physical, psychological, and environmental inputs
- Adapts dynamically to maintain and change its own function
- Facilitates coordinated conscious and unconscious reactions of multiple body systems
287
What are the determinants of the mechanical properties of the nervous system?
- Continuity of nervous tissue tract
| - Supporting connective tissues
288
What are the determinants of the mechanical properties of the nervous system in the peripheral nervous system?
- Interneural and intraneural plexus formation
| - Quantity of fascicles housed within nerve
289
What are the determinants of the mechanical properties of the nervous system in the central nervous system?
- Folding and twisting of axons
| - Nervous tissue movement in relation to neighboring bony segments
290
Interneural plexus formation in the PNS serves to ___
Interneural plexus formation in the PNS serves to * distribute force within combinations of nerves*
291
Intraneural plexus formation in the PNS serves to ___
Intraneural plexus formation in the PNS serves to *distribute force within specific
nerves*
292
How does the quantity of fascicles housed within peripheral nerves determine of the mechanical properties of the nervous system?
Nerve compression with greater pressure
| required to affect nerve fibers in a nerve with a smaller number of fascicles
293
How does the folding and twisting of axons
| within the central nervous system determine of the mechanical properties of the nervous system?
Redundancy within the tissues of the central nervous system allows neural structures to elongate prior to being exposed to significant tensile forces
294
Normal movement of the body requires that
| tissues of the ___ be able to move past adjacent structures in which they are housed
Normal movement of the body requires that
| tissues of the *central nervous system* be able to move past adjacent structures in which they are housed
295
What are the mechanical load that nervous system tissues are exposed to?
* Compression
* Tension
* Excursion
296
Compression can lead to alterations in ____ which can occur at relatively low pressures
Compression can lead to alterations in *fluid and blood flow within neural tissue* which can occur at relatively low pressures
297
Exposure to compression is normal if ___ and ___ are not excessive
Exposure to compression is normal if *magnitude of forces and duration of exposure* are not excessive
298
True or false
Neural tissue is not elastic
True
299
Increased tensile loading leads to ___ cross sectional area and increased _____
Increased tensile loading leads to *decreased* cross sectional area and increased *intraneural pressure*
300
When does blood flow begin to decrease?
At 6-8% strain or elongation
301
When is blood flow completely arrested?
At 15% strain or elongation
302
What is excursion?
The ability of the neural tissue to “slide” relative to adjacent interfacing extraneural
tissues
