Download lecture06-MSK-physiology

Joints, Movement,
Somatic Nervous System
Jim Pierce
Bi 145a
Lecture 6, 2009-10
Joints
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Fibrous Joint
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Cartilaginous Joint
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Syndesmosis
Intraosseus Membrane
Ribs, Costal Cartilages, Sternum
Vertebrae and Intravertebral Column
Synovial Joint
Fibrous Joint
Cartilaginous Joint
Synovial Joint
Plane Joint
Pivot Joint
Hinge Joint
Saddle Joint
Ball and Socket
Condyloid Joint
Synovial Joint
Knee
Muscles and Joints
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With each moveable joint
comes a set of muscles
These muscles have an origin
and an insertion (usually into bone)
How does a muscle move a joint?
Force Generating Axis
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Muscle fibers generate force
The muscle organ generates a force
which is the vector sum of the forces
of its fibers
The magnitude of that force is
often erroneously called “force”
The direction of that force is called
the Force Generating Axis
Force Generating Axis
Deltoid Muscle
Force Generating Axis
Fiber Force Vectors
Force Generating Axis
Muscle Force
Types of Muscle
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Muscles come with all
different fiber orientations!
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Longitudinal – All fibers run parallel
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Pennate – Some Fibers are at an angle
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Unipennate – All fibers are at one angle
relative to the Force Generating Axis
Multipennate – Fibers run at multiple angles
relative to the Force Generating Axis
Types of
Muscle
Strap (a.k.a.
Parallel)
Fusiform (a.k.a.
Spindle Shaped)
Multipennate
Unipennate
Bipennate
Types of Muscle
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Muscle (organs) come in different
shapes
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Flat / Strap
Flat / Quadrate
Fusiform
Convergent
Sphincter / Circular
Pennate
Types
of
Muscle
Muscle Organ
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All these different shapes operate under
the same principle:
Total Force is produced the
Force Generating Axis
Force Generating Axis
Tendon / Insertion
Muscle Insertion
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What happens if the force generating
axis does not have the same direction
as the tendon?
The “rest” of the muscle
will tighten or move!
Hence… “Butt Wiggling”
Example
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The Buttocks demonstrate these concepts
Scary!
Gluteus Maximus
Gluteus Maximus
Clench your butt
- Notice your knee move
When you use the
muscle, the output
is through the tendon
Gluteus Maximus
When your primary
goal is walking,
You will still get
“butt movement”
Gluteus Minimus
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Gluteus Minimus and Medius
hide under Maximus
They spread the legs
Gluteus Minimus
During relaxation,
the femur neck
supports
body weight
Gluteus Minimus
During contraction
the femur head
rotates around
the hip joint
Joint Function
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The Skeleton is designed to:
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Support weight across joints
Resist Fracture
The Muscles are designed to:
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Produce movement across joints
Have active and passive properties
Joint Function
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Crossing each joint are multiple muscles
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By having its own origin and insertion,
each muscle creates a unique torque
Muscles are paired (flexor – extensor)
or grouped (Quads and Hamstrings)
so that all muscles, at light contraction,
balance the joint in anatomic position
Joint Function
Together,
the skeleton and
these muscles
produce joint function
Nervous System
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Central Nervous System
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All the parts of the nervous system
that are INSIDE of bone
Peripheral Nervous System
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All the parts of the nervous system
that are OUTSIDE of bone
Peripheral Nerve
Axons
Peripheral Nerve
Peripheral Nerve
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We can
follow the
axon to find
the other
parts
Peripheral Nerve
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We find
TWO TYPES
of neuron
Dorsal
Location
Ventral
Location
Sensory Neuron
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Dorsal
Location
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Dendrites in
the Body
Soma in
Dorsal Root
Synapse
in Spinal Cord
Motor Neuron
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Ventral
Location
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Dendrites and
Soma in
Spinal Cord
Synapse
in Muscle
Peripheral Nervous System
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Sensory
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Brings information into the Spinal Cord
Lives Dorsally
Motor
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Takes information to the muscle
Lives Ventrally
Peripheral Nervous System
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Sensory
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Motor
Motor
System
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Posture
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Movement
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Function
Motor System
Motor System
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The Motor System has TWO parts:
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The Upper Motor System
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Brain and Spinal Cord
Planning, Coordinating Movement
Starting, Stopping Movement
Motor System
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The Motor System has TWO parts:
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The Lower Motor System
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Spinal Cord, Peripheral Nerve, Muscle
Making Muscles Contract
Making Body Parts Move
Motor System
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Upper Motor
System
Lower Motor
System
Lower Motor System
Lower Motor Neuron
Lower Motor System
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The Lower Motor
System is made up
of Motor Units
Each Motor Unit is
a Lower Motor Neuron
and all the muscles
it controls
Lower Motor System
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Dendrites
Soma
Axon
Lower Motor Neuron
“Muscle Synapse”
(Neuromuscular Junction)
Muscle
Muscle
Neuromuscular Junction
Muscle Synapse
Action Potential vs Contraction
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Action Potential = RED
Muscle Force = BLACK
Action Potential vs Contraction
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Lower Frequency = Less Force
Higher Frequency = More Force
Lower Motor System
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The Neuron of each motor unit…
Tells the muscle when to contract
and how much force to make
What do the Soma
and Dendrites do?
Lower Motor System
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Dendrites and Soma = Receive Input
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Axon Hillock = Make Decision
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Together, they listen to the Upper and
Lower Motor Systems, and decide
when to activate the muscle
Lower Motor System
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Examples of
the decision:
Brain says move
Action potential
arrives through
Spinal Cord
Lower Motor Neuron
Tells muscle
to Contract
Lower Motor System
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Examples of
the decision:
Brain says STOP
Fewer action
potentials arrive
via Spinal Cord
Lower Motor Neuron
does not tell
muscle to contract
Lower Motor System
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Key Point:
The Lower Motor Neuron decides
when muscle will contract and relax
Lower Motor System
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Why this separation?
Lower Motor System
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Upper MS says “BEND ARM” to
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Bicep Lower MS
Tricep Lower MS
Bicep Lower MS
says “CONTRACT”
Tricep Lower MS
says “RELAX”
Motor System
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This is a common theme:
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There are many levels of control
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Higher levels do more complex things
Lower levels do more simple things
Lower Motor System
Upper Motor System
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Why have an upper motor system?
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We need to:
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Plan and rehearse movement
Remember practiced movements
Coordinate complex movements
Start Stop movements
Upper Motor System
PLAN
EXECUTE
Upper Motor System
PLAN
START AND STOP
EXECUTE
Upper Motor System
PLAN
START AND STOP
EXECUTE
COORDINATE
Upper Motor System
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The first clue
came from
brain injury
People with
injury to the
area in RED
couldn’t move
Upper Motor System
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Thus, the
RED area
is called…
PRIMARY
MOTOR
CORTEX
Upper Motor System
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Injury to Specific Areas
Causes Specific Motor Dysfunction
Upper Motor System
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Activation of Specific Areas
Causes Specific Movements
Upper Motor System
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Mapping is now
done by fMRI
This is a person
moving his thumb
Cortex
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Cortex (in general)
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Made up of layers:
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White matter = Wires
Grey Matter = Cells
Gyri (gyrus) = Peaks
Sulci (sulcus) = Valley
Cortex
Carefully looking at
the grey matter, we
find cells in layers
Cortex
If we look
closely at
any cortex…
We find an
important cell
The
Pyramidal
Cell
Primary Motor Cortex
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If we follow the
AXON of the
pyramidal cell…
Cerebral White Matter
Brain Stem White Matter
Crosses to Opposite Side
Spinal Cord White Matter
Synapses with the Lower
Motor Neuron (and others)
Upper Motor System
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Just like the Lower Motor Neuron is the
central part of the Lower Motor System
The Pyramidal Cell of the Primary Motor
Cortex is the central part of the
Upper Motor System
Lower Motor System
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Pyramidal Neuron says “BEND ARM” to
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Bicep Lower MS
Tricep Lower MS
Bicep Lower MS
says “CONTRACT”
Tricep Lower MS
says “RELAX”
Upper Motor System
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Brain Injury,
fMRI, and
Stimulation
identified other
important areas
BLUE =
Premotor
Cortex
ORANGE =
Supplementary
Motor Cortex
Upper Motor System
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Further fMRI and ablation studies
identified that Pre-motor and
Supplementary Motor Cortex…
Were necessary for:
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Complex Motor Skills
Planning Motor Skills
Rehearsal of Motor Skills
UpperPre-Motor
Motor System
“FLEX ARM”
UMN – Shoulder UMN – Elbow
“Out to Side”
“90 Degrees”
UMN – Wrist
“Turn in”
UMN – Hand
“Fist”
UMN – Tricep
UMN – Bicep
“Really Contract” “Really Contract”
LMN - Deltoid
LMN - Latissimus
LMN - Bicep
LMN - Tricep
LMN – Hand Intrinsics
LMN – Wrist Flexors
Upper Motor System
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There is more to complex motor skills
than just coordinating the muscles…
We need to pay attention to our
SENSORY system.
We need to plan our movements
accordingly.
Upper Motor System
Upper Motor System
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Key Point:
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The motor system is like an army!
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To get a more complex skill,
We add a higher rank.
Upper Motor System
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How can we coordinate this movement?
Some system needs to check
ALL the inputs and outputs
Then it needs to give feedback.
Upper Motor System
Purkinje Cell
Cerebellum
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There is a
circuit that
travels from
Motor Cortex
to Cerebellum
Upper
Motor
System
Cerebellum
Cerebellum
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Everything
is an input
(orange wires)
Purkinje cells
are the
“THERMOSTAT”
Cerebellum
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The cerebellum coordinates
movement by checking everything
and giving feedback.
Upper Motor System
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How do we get
started?
RAS = Keeps
brain awake
Upper Motor System
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Basal
Ganglia
Basal Ganglia
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Main Parts:
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Caudate
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Putamen
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Globus
Pallidus
Basal Ganglia
Basal Ganglia Circuit
CAUDATE,
PUTAMEN,
and
SUBSTANTIA NIGRA
are INHIBITORY
GLOBUS PALLIDUS
is INHIBITORY
Basal Ganglia
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Globus Pallidus
keeps all
movement OFF
Caudate and
Putamen turns
G.P. OFF…
Which turns
Cortex ON!
It’s like a race car revving its engine:
putting the car in gear starts the car!
Basal Ganglia
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Caudate and
Putamen are
under two
controls:
SENSORY
SUBSTANTIA
NIGRA
Substantia Nigra
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Substantia Nigra is responsible for
letting the Caudate and Putamen
start and stop behaviors.
Diseases of
the S.N. cause
MOVEMENT
DISORDERS
Upper Motor System
Questions?