Biomechanics Midterm Flashcards
0
Q
What is the arrangement of fusiform muscles (spindle shaped)?
How does their range of motion compare?
A
fibers arranged parallel and with large cross section diameter
produce a greater range of movement than similar sized muscles with pennate arrangement
1
Q
What are parallel muscles?
A
fibers arranged parallel to the length of the muscle
2
Q
Pennate muscles
A
Have shorter fibers
3
Q
Unipennate muscle
A
attached to main tendon; fibers come in at an angle
ex. ext. digitorum
4
Q
bipennnate musclle
A
ex. rectus femoris
pulls on centraltendon ith fibers on both sides
5
Q
multipennate
A
multiple groups of fibers converge on one tendon in various directions
ex. deltoid
6
Q
Convergent muscles (fan shaped)
A
broad origin, pointed insertion
the direction of the pull can be varied –> versatile
ex. pectoralis major –> different parts can be active at different times
7
Q
Circular muscles
A
sphincters, eyes, mouth
closes down round areas
8
Q
Muscle Actions
A
Strength, power and torque
9
Q
Muscle action: strength
A
the max force a muscle can produce for a single max effort
the amt of tension a muscle produces
10
Q
muscle action: power
A
work done over a given period of time (work/time)
a muscle contracting in a very brief amount of time (high power)
11
Q
muscle action: torque
A
muscle force causing rotary movement of a body around an axis; a turning or twisting force
12
Q
Muscle action: Contraction
What can they be used for?
A
tension developed in a muscle as a result of a stimulus
Used for: cause, control and prevention of joint movement
- initiate or accelerate movement of a body segment (usually contraction)
- slow down or decelerate movement of segment (usually stretching/lengthening –> controlling)
- prevent movement of a body segment
13
Q
What are the main types of muscle contraction?
A
Isometric (same measure): muscles do not shortern/lengthen, but still produce tension
Isotonic: (same tone) lengthen or shorten, but maintain a consistent tone
- Concentric: to the center; bring together
- Eccentric: away from the center; bring apart
14
Q
Isometric contraction
A
tension developed within a muscle without joint motion –> static contractions
Occurs when the tension a muscle develops is the same as the force applied to that muscle
USED TO STABILIZE JOINTS
15
Q
Isotonic contractions
A
muscle contraction without appreciable change in the force contraction –> maintains tension under a constant load
- tension is developed within a muscle
FINISH
16
Q
Concentric contraction
A
muscle develops tension as it shortens
occurs when a muscle develops enough tension to overcome the resistance appllied to it
used to initiate movement against gravity or resistance
17
Q
Eccentric contraction (away)
A
muscle lengthens unders tension (gradual lowering under high weight)
muscle tensions is less than the resistance applied to it
- results in controlled joint motion
USED TO DECELERATE BODY SEGMENT MOVEMENT
**produce the most tension out of all types of contraction; most demanding type of contraction
18
Q
Line of pull
A
direction of movement produced by the contracting muscle
- the pull of a muscle from its rigin to insertion
change can occur with change in joint position
19
Q
Line of pull is a function of what/
A
the muscles attachment
the plane of joint motion
the muscles distance from the joint’s axis of rotation
20
Q
What happens when the line of pull is altered from its optimal position due to muscle weakness or poor posture?
A
the muscle will be inefficient, work harder and have more strain put upon it.
This can lead to muscle and/or joint injury.
21
Q
Angle of pull**
A
the angle betewen the line of pull of the muscle and the bone on hich it inserts
- a muscles angle of pull changes with every degree of joint motion
- a vertical component of the angle is always perpendicdular to the lever (attachment) and causes rotational movement at the joint axis (90* –> 100% rotational)
- a horizontak component of the angle of pull is always parallel to the lever and causes non-rotational movement at the joint axis (angle or 45*
22
Q
What is muscle action is dependent upon?
A
# of motor units activated type of motor unit activated size of the muscle initial muscle length angle of the muscle and joint speed of muscle contraction
23
Q
Reverse action of concentric muscle contractions
A
when a muscle contracts it pulls both ends toward the center of the muscle
- if neither of the bones attachments are stabilized, then bones are puled toward another
- usually, one bone is more stabilized and the less stabilized bone usually moves toward the more stabilized (ex. biceps curl - open chain; chin up - closed chain)
24
Range of motion
depends on length of muscle fibers (long = large range; parallell and fusiform muscles)
25
What does power depend on?
total number of muscle fibers
many fibers = great power
(convergent, unipennate, bipennate, multipennate muscles)
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4 Properties of muscle force production and movement
irritability or excitability
contractility
extensibility
elasticity
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Irritability (excitability)
property of muscle being sensitive or responsive to chemical, electrical or mechanical stimuli
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Contractility
ability of muscle to contract and develop tensions (innternal force) against resistance when stimulated
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Extensibility
ability of muscle to be passivle streatched beyond its normal resting length
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Elasticity
ability of muscle to return to its original length following stretching
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Interdigitation
a muscle may be innervated by more than one nerve and a particular nerve may innervate more than one muscle
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What roles doe muscles work in?
Prime mover (Agonist)
Antagonist
Synergist
Stabilizer (fixator)
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Prime movers (Agonists)
muscles that assume the major responsbilioty for producing a specific movement
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Antagonists
muscles that oppose or revers the movement by prime mover
- if the prime mover is active, antagonist is released
- antagonist also help regulate the action of the prime mover by partially contracting to provide some resistance or to slow or stop
35
Synergist
a musclle which performs or assists the same same join motion as the agonist
- two muscles are callded synergeists that act to control morion of the prime mover
- immovbilizw the origin of the prime mover so that the prime mover can act more efficiency
36
STabilizers (fixator)
synergists that act to control motion of the prime mover
- immobilize the origin of the prime mover so that the prime mover can act more efficiently
- tends to be continuous low-level muscle activity with either isometric or eccentric pull
(ex. deltoid is the prime mover of arm abduction)
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Mechanical Levers
Purely physical
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LEver
a riigid bar that moves on a fixed point (bones)
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Fulcrum
a fixed point of leverage (joint)
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Effort
force appllied to move a resistance (tension/torque)
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Load
resistance to be moved (bone, tissue mass and objects to be moved)
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Mechanical advantage lever 9power lever)
load is close to fulcrum
effor applied far from the fulcrum
small effort appllied over a relatively long distance can be used to move a large load over a small distange
* such a leverl operates as a mechanial advantage and is commonly caled a power lever
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Mechanical Dsiadvantage (speed leverage0
load is far from fulcrum
efost is applied new the fulcrum
The force exerted must be great ha the moved moved
- useful because they allow the load to move rapidly through a larger range of motion
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Mechanical Muscke
A lever allows
45
1st class levers
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Second class levers
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the load (resistance) lies between fulcrum and effort
* we dont have many of these
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Third class levers
*Most of what we have in the body
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effort is applied at t apoint between the load and the fulcrum
great speed with mechanical disadvantage
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Functional Organization of Skeletal Muscles
Muscles --> fascicles --> muscle fibers (cells) --> myofibrils --> Thick and thin filaments
Each layer is wrapped with fascia
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Sarcomere
Contains Thick and Thin Filaments
| Make up a Myofibril
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Myofibrils
Surrounded by: Sarcoplasmic Reticulum
| Consists of: Sarcomeres
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Muscle Fiber
Surrounded by: Endomysium
Contains Myofibrils
Types: Fast, ballistic (glycolytic fuel source); postural;
* Can contain multiple types of fibers
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Muscle Fascicle
Surrounded by: Perimysium
| Contains: Muscle Fibers
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Skeletal Muscle
Surrounded by: Epimysium
| Contains: Muscle Fascicles
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Neuromuscular Juntion
| What are the 5 basic components?
The site where the axon and muscle fiber communicate
1. Motor Neuron
2. Motor end plate
3. Synaptic Cleft
4. Synaptic Vesicles
5. Neurotransmitters
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What is the motor stimulation mechanism for muscle contraction?
Motor impulses cause the release of acetylcholine (ACh) from synaptic vesicles which bind to receptors on the motor end plate and generate muscle contraction
56
What is the process of muscle relaxation?
acteylcholinesterase breaks down acetylecholine
motor neuron impulses stop
calcium moves back into sarcoplasmic reticulum
myosin and actin binding prevented
57
What is a motor unit?
a single motor neuron and all the muscle fibers it controls
- the functional connection between the nervous system and the muscular system
- when a motor unit fires, all the muscle fibers contract together
- one neuron may innervate several muscle fibers
- one muscle fiber may be innervated by several motor neurons
- - this creates both large and small motor units
- One muscle fiber may act with several motor units depending upon demand (interdigitation)
58
What is an example of fine control? Strength control?
```
extraocular muscles (20 fibers)
gastrocnemius (1,000 fibers)
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59
Twitch
a single brief stimulus to a muscle that produces a quick cycle of contraction and relaxation lasting less than 1/10 second
- a single twitch is not strong enough to do any useful work
- normal activities require more tension than is produced this way
- CHART ON TETANUS - measure twitches by pulses per second --> summation of twitches --> tetani
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Treppe
Gradually increased contraction intensity... a rapid sequence of stimuli cause the muscle twitches to fuse together, each contraction being stronger than the one before... gradually generate more strength contraction
- occurs with
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Tetanus (incomplete)
very rapid sequence of stimuli
| - occurs with higher frequency stim
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Tetanus (complete)
very rapid sequence of stimuli
| 50 + pps
63
What are the 3 functional classifications of neurons?
Sensory
Motor
Interneuron
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Sensory Neurons
afferent neurons
| - transmit impulses from receptors to the brain or spinal cord
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Motor neurons
efferent neurons
| - transmit impulses from the brain or SC to the effetor sites such as muscles, glands or organs
66
Interneuron
association neurons
| - transmit impulses from one neuron to another --> bridge
67
Nociceptive neurons
"Pain" fibers
"warning fibers"
(MOTOR Neurons)
68
Nerve Fiber classification
A, B, and C *doesn't test much on this
69
A fibers: myelinated
| subtypes
A alpha: fastest conducting and largest diameter; motor efferents; muscle spindle afferents
A - beta(50 ms): touch and pressure afferents (mechanoreceptors)
A-gamma (20 ms): motor efferent to muscle spindle
A-delta (15 ms): skin temperature and pain (noxious stimuli)
70
B fibers
7 ms
| myelinated, slow
71
C fibers
unmyelinated
we don't deal much with these
temperature, pain, itch
72
What is the Spinal Cord Reflex Arc
a functional unit of the nervous system; automatic response to stimulus without conscious thought
73
What are the 5 basic components of the spinal cord reflex arc
1. sensory receptor: transmits APs stimulated by sensation
2. Sensory Neuron: transmits impulses to SC
3. Interneuron: connects or switches impulses to other neurons
4. Motor Neuron: transmits motor impulses
5. Effector Organ: responds with reflex contraction of muscle or gland
74
Proprioception
The sense of position and movement of one's sown limbs and body without using vision (somatosensory)
- sense of body and limb position
- sense of speed and direction of limb joint movement
- sense of muscle length and tension
* Travels on posterior tracts - dorsal columns (myelinated) to increase speed of information
75
What 3 types of mechanoreceptors detect proprioception
1. Muscle spindle Receptors
2. Golgi tendon organs: located in tendons of muscle, neuromusc jxn
3. Joint kinesthetic receptors:
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Muscle Spindle Receptors
located within the fleshy part of the muscle and consists of special intrafusal muscle
- ends of the intrafusal fibers are contractile and attach to the extrafusal fibers
- the spindle detects the rate at which the muscle fibers are stretched and their length
- changes in length of muscle fibers aids in coordination and efficiency of muscle contraction
77
Muscle Spindle Receptors: Intrafusal Muscle fibers
| What are the 2 types?
modified muscles fibers enclosed in a capsule within extrafusal fibers (normal, voluntary skeletal muscle)
1. Nuclear Bag Fibers
2. nuclear chain fibers
78
Nuclear Bag Fibers
nuclei are concentrated in the central "bag" part of the fiber
- the ends of the fibers are striated and contractile
- the contractile fibers are attached to the extrafusal fibers
- the contractile ends receive input from gamma motor neurons
- the nuclear bag is sensitive to sudden rate of change in muscle length (phasic)
79
Nuclear Chain fibers
nuclei are spread in a "chain like" fashion in the center of the fiber
sensitive to slow stretch
80
muscle spindle cont'd
central non-contractile region s a wrapped buy type Ia and type II sensory neurons that send input about the rates and amount of length change to CNS
REVIEW SLIDES FOR MORE INFO
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Agonists
causes specific movement or possibly several movements to occur through the process of its own contraction
82
Antagonists
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Golgi Tendon Organs (GTOs)
encapsulated nerve endings located at the junction of tendon and muscle; their ends have numerous terminal branches associated with bundles of collagen fibers in the tendon; produces a sudden relaxation of the muscles; Plays a role in muscle tone imbalance, muscle spasm and tendon points
Sensory Innervation only
Dynamic response: sudden increase in muscle tension
AND Static Response: sustained or gradual pull (postural tone)
INVOLUNTARY MUSCULAR RELAXATION
84
What do GTOs detect?
Detects:
- force of muscle contraction
- tension applied to the tendon
- prevents contracting muscle from applying excessive tension to tendons
85
Joint Kinesthetic Receptors
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located in and around synovial capsules, in ligaments
- encapsulated and free nerve endings
Detect:
- direction of movement of the join
- acceleration
REVIEW
Types: Pacinian, Ruffini, Free nerve
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Pacinian Corpuscles
located in CT and synovial joint capsules
| respond to rapid pressure changes, stretch, acceleration and deceleration of joint movement
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Ruffini Corpuscles
located in synovial capsules and ligaments
respond to deep rapid and sustained pressure; especially responsive to lateral stretch
detects changes in joint angles
ligament receptors adjusts muscle tone
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Free nerve endings
located in most body tissues - joint capsules, ligaments, tendons, fat pads, menisci and periosteum
respond to rapid and sustained pressure
89
Proprioceptors Affect on Muscle Tone
| 3 reflexes
- automatic response without conscious through
1. Quick Stretch Reflex
2. Reciprocal Inhibition
3. Autogenic Inhibition
90
How is the reflex arc tested?
Tested by DTRs: deep tendon reflexes --> test the simple reflex arc
hyporeflex: inhibit reflex; diminished reflexes
hyper-reflex: upper motor neuron (SC, brainstem, cerebellum and up) lesion?
91
Quick stretch reflex
telex response from muscle spindles
- produces contraction of the muscle being stretched
- fxns: monitors status of muscle activity; guards against potential injury; respond to rapid and sustained pressure
MORE INFO IN SLIDEs
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Reciprocal Inhibition
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Autogenic Inhibition
a muscle inhibits itself - an inhibitory response to a muscle that develops too muscle tension, either via shortening or lengthening
comes through the GTOs
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FXNS of Autogenic Inhibition
- guards against potential injury to a muscle's fibers
| - muscle relaxation reduces tension applied to the muscle and endows and protects them from damage
95
Sequence of Autogenic Inhibition
stretching the tendon (via contraction or passive stretch) increases the tension in the tendon and activates the afferent GTOs
- the GTO neurons synapse in the SC with inhibitory interneurons
REVIEW remainder
--> GTO stretched --> Ib afferent --> inhibitory interneuron relaxes agonist --> excitatory interneuron contracts antagonist
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Roll
multiple points along one rotating articular surface contact multiple points on another articular surface
(a tire rolling across the pavement)
femoral condyle on the tibial plateau
occurs on incongruent (unequal) surfaces
usually occurs in combination with sliding or pinning
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Slide
(glide) a single point on one articular surface contacts multiple points on another articular surface
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Spin
(like a top on the floor) a single point on one articular surface rotates on a single point on another particular surface; rotates around a stationary longitudinal mechanical axis
ex. head of the radius at the humeroradial joint during pronation and supination
* does not occur by itself during normal joint motion; occurs as a combination motion
99
Distraction and longitudinal traction
joint surfaces are pulled apart
| use to stretch a joint capsule and mobilize a joint
100
Compression
decrease in the space between two joint surfaces
adds stability to a joint
normal response to muscle contraction
101
Can arthrokinematic movement between joint surfaces be reproduced by muscles?
No, they must be produced in the joint on their own. It is what we are restoring during manipulations.
102
Convex-on-concave and vice versa rule:
describes the relationship of rolling and sliding motion within a joint when one joint surface is convex and the other surface is concave
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Convex on concave motion
the concave side = stabilized (anchored)
| the convex joint surface slides in the opposite direction as it rolls
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Concave on convex motion
the convex side = stabilized
| the concave joint surface
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Clinical significance of Convex-concave rule
- rules serve as a basis for joint mobilization techniques
- physiological movements
- accessory movements
- joint play
- end-feel
- Tx often combines facilitation of physic mobilization and accessory movements to restore particular joint movement
- ONE MORE
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Physiological Movements
movement of bones done voluntarily (osteokinematics)
107
Accessory Movements
the name given to the arthrokinematic movements within the joint and surrounding tissues that are necessary for normal joint range of motion, but cannot be performed voluntarily
- necessary for full range of physiological motion to occur
- ligament and joint capsule limitations cause movement restrictions or aberrant joint motion
108
Joint Play
motions that occur within the joint but only as a response to an outside force
- determined by joint capsule's laxity
- can be demonstrated passively, bout not performed actively
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End-feel
a way to interpret and measure joint play movements
| what stops it? joint capsule, scar tissue, etc.
110
Joint Mobilization Techniques
ADD INFO
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Plane
a flat surface determined by the position of three points in space
- sagittal
- frontal (coronal)
- transverse (axial)
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Plane motion
motion in which all points of a rigid body move parallel to a fixed plane (two dimensional movement)
113
What plane motion occurs in the sagittal plane?
- flexion
| - extension
114
That plane motion occurs in the frontal (coronal) plane?
right and left lateral flexion
115
motion occuring in the transverse (axial) plane?
ADD
116
Axis of motion
a line around which rotary movement takes place or along which translation occurs
117
X, Y and Z axes
sdf
118
Degrees of freedom
the number of ways in which a body can move
- one degree of freedom would be translation or rotation about one axis
- spinal segments exhibit 6 degrees of freedom
119
Instantaneous Axis of Rotation (IAR)
when a rigid body moves in a plane, at every instant there is a point in the body or some hypothetical extension of it that does not move; AXIS IS MOVEABLE/DYNAMIC
- an axis perpendicular to the plane of motion and passing through that point is the instantaneous axis (center) of rotation for that motion at that instant
- used to describe any vertebra motion in 2D space
- as different force vectors are applied, they may cause a shift in the IAR
120
Motion Segment
the functional unit of the spine
- smallest spinal segment exhibiting biomechanical characteristics similar to those of the entire spine
- 6 degrees of freedom (6 joints on each vertebra)
- 2 adjacent vertebrae and everything that connects them.
121
Pain generators of the spine
outer third of the disc, the ligaments that attach to vertebrae, intersegmental muscles, capsules around the facet joints
122
Coupled Motion
the consistent association of one motion (translation or rotation) about one axis with another motion about a second axis
- one motion cannot be produced without the other
- two motions occurring at the same time along two different axes.
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loose-packed joint position
- joint capsule and ligaments are most relaxed
- max joint play is possible
- articulating surfaces are maximally separated
- position used for traction or joint mobilization
* facet joint loose-packed position = half way between flexion and tension
124
closed-packed joint position
- the capsule and ligaments maximally tightened
- there is no joint play
- there is maximal contact between the articular surfaces
* either in flexion or extension
125
spine review
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33 vertebrae (7 C, 12 T, 5 L, 5 S, 1 - 4 Coccyx)
Cervical = a lot of rotation;
Thoracic Nn = autonomic (sympathetic)
Cervical and Sacral (Craniosacral) Nn = parasympathetic
** don't only be thinking about muscles and joints --> Nervous System too!
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126
Regional Coupling
more than one motion is occurring at the same time
127
Occiput (CO)
Condyles:
- face laterally and inferiorly
- form convex rockers
- sit in concave surface of superior articular facet of C1
128
Atlas (C1)
Facets:
- concave surface
- ADD INFO
129
C0-C1 Flexion and Extension
| Lateral Flexion
FLEX/EXTEN:
- occiput glivers post. with flexion and ant. with extension
greatest range of motion in C0-C1
- ROM: excursion is 10* flexion to 25* extension
LATERAL FLEX:
- occiput rolls on side of lateral flexion and glides on opposite side; ROM = 5* each side (minimal)
**IMPT to know about stability bc too much movement could put pressure on SC
130
Lower Cervical Biomechanics (c3-c7)
Design is consistent from C3 - C7
Vertebral body is wider transversely than A-P
Transverse foramen for vertebral artery
*bifid spinous processes
131
Articular facets for lower cervicals - describe angles in planes and the articular surface.
articular facets are at a 45* angle with transverse (horizontal) plane
parallel in frontal (coronal) plane
articular surface is nearly flat
* coupled motion
132
Joints of Lushka
aka uncinate processes; give the cervical spine more stability
form age 6 - 9 and completed by age 18
limit lateral flexion to only a few degrees
serve as guides to couple lateral flexion with rotation (coupled motion)
synovial joints; can become inflamed
133
Curves of the cervical spine
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Lordotic curve of 20 - 50* (average is 45*)
begins C1 and extends to C7
facet and disc planes determine curve
secondary curve
develops in response to upright posture.
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134
cervical something
disc-height-to-body ratio: 2.5, allows for greater TOM in cervivals
25% height of cervical curve
highly anteriorly, conntibutes to cervical lordosis
nucleus pulposus slightly posterior ot center
135
Lower cervical Flexion and Extension
Flexion and extension predominate over the other motions
average range of motion is 15* per segment for combined flex-extension
*important, moving forward and backward of one vertebrae on the other
136
Flexion - lower cervical
anterior disc compression --> posterior distraction
| Facets glide apart producing stretching and joint gapping
137
Extension - lower cervicals
anterior disc distraction - posterior compression
| facets approximate --> compression at inferior margins
138
Lateral Flexion of C vertebrae
average lat flexion range is 7 - 8* to each side
lateral flexion decreases as move caudally down cervical spine
coupled motion MORE INFO
lateral disc wedging and approximation are present on the side of lateral flexion and distraction is present on the side opposite lat flexion
- the inferior facet glides down and medially on the side of lateral flexion and up and laterally on the side opposite lateral flexion
139
Lower cervical rotation
average ROM = 5* to each side
rotation decreases significantly
lateral flexion gets a lot of rotation , but rotation only gets a little of lat rotation
140
Typical Thoracic Biomechanics
transverse processes are thick, strong and long
SPs are long and slender
Costovertebral joints on side of vertebral bosy articular with rib heads
costotransverse joints on TVPs articulate with tubercles of ribs
141
Thoracic Curve
Forward curve - primary curve at birth
kyphotic curve of 20 - 50* (average = 45*)
begins t1-t2 and extennds to T12
apex is at T6 - T7 disc space
flattening will cause: cervical curve to decrease, cervical curve to shift forward, lumbar curve to increase
lumbar curve to
142
Thoracic disc
not as vulnerable as cervical or lumbar area
disc height to body ration = 1:5; smallest ratio in spine
contributes to decreased flexibility in thoracic spine
nucleus pulposus located centrally within annulus
143
Flexion and extension - thoracics
combined flex-exten = 6*; 4* in upper thoracics, 6* in middle, 12* in lower
combines sagittal plane rotation (tilting) with slight sagittal plane translation
Flexion - articular facets glide apart as the disc opens posteriorly
Extension - facet joints and posterior disc approximate
144
coupled motion
approx 6* to each side
upper thoracic lat flex is couple with axial rotation
- upper thoracic lat flex and trptation occur to the sam side, body r
- middle and lower can go either way
145
upper thoracic rotation
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