Download Human Movement Systems: Nervous System

Human Movement Systems:
Nervous System
Objectives
• After this presentation, the participant will be able to
explain:
– The Human Movement System
– Nervous System Organization
– Sensory, integrative and motor functions
– Neurons
– The role of vision, proprioception & vestibular systems in
kinesthesia.
– Common sensory receptors and their role in proprioception
and movement.
Introduction
Human Movement System:
• Movement is accomplished through the functional
integration of three systems: the nervous, skeletal,
and muscular systems.
• These systems work in concert to produce motion
(kinetic) or human movement.
• All components must work together to produce sound
movement; if one component is not working well, it
will affect the others and cause kinetic chain
impairments.
Kinetic Chain
The kinetic chain
• Kinetic means related to movement; chain refers to
a system that is linked together or connected.
• All components work together to manipulate
human motion.
• If one component of the kinetic chain is not
working properly, it will affect the others and
ultimately affect the movement.
Kinetic Chain
Nervous System
Muscular System
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Skeletal System
The Nervous System
 The nervous system is a
communication network within
the human body that allows us to
gather information about our
internal and external
environments, process and
interpret the information, and
respond.
 Its three primary functions are:
•
Sensory
•
Integrative
•
Motor
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Nervous System
 Sensory: The ability of the nervous system to sense
changes in either the internal or external
environment.
 Integrative: The ability of the nervous system to
analyze and interpret the sensory information to allow
for proper decision making, producing the appropriate
response.
 Motor: The neuromuscular response to the sensory
information.
The Nervous System
 Movement is a response to our
sensory information and is,
therefore, dictated by the nervous
system.
 This reflects the importance of
training in a multisensory
environment.
 The most effective way to create
positive long-term results in a client
is to directly affect (properly train)
his or her nervous system.
Nervous System Organization
Central Nervous System
The CNS consists of the brain and the spinal cord.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Peripheral Nervous System
 Contains 12 cranial nerves and 31 pairs of spinal nerves (that
branch out from the brain and spinal cord, respectively) as well as
all sensory receptors.
 Function:
•
Provide a connection for the nervous system to activate different bodily
organs such as muscles (motor information).
•
Relay information from the bodily organs back to the brain, providing a
constant update of the relation between the body and the environment
(sensory information).
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Peripheral Nervous System
Two further subdivisions of the PNS include the somatic
and autonomic nervous systems:
• The somatic nervous system consists of nerves
that serve the outer areas of the body and skeletal
muscle and are largely responsible for the voluntary
control of movement.
• The autonomic nervous system supplies neural
input to the involuntary systems of the body.
• The autonomic system is further divided into the
sympathetic (activity state) and parasympathetic
(recovery state).
The Neuron
 The functional unit of the
nervous system is known as the
neuron.
 Neurons are composed of three
main parts:
•
Cell body: Cell organelles
(nucleus, mitochondria,
lysosomes, and Golgi
complex)
•
Axon: Provides
communication from the
brain or spinal cord to other
parts of the body
•
Dendrites: Responsible for
gathering information from
other structures of the body
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Neuron
There are three main functional classifications of
neurons determined by the direction of their nerve
impulses:
• Sensory: Transmits afferent nerve impulses from
receptors to the brain or spinal cord
• Motor: Transmits efferent nerve impulses from the
brain or spinal cord to the effector sites, such as
muscles or organs
• Interneuron: Transmits nerve impulses from one
neuron to another
Proprioception
 The body’s ability to sense the relative position of
adjacent parts of the body.
 Training the body’s proprioceptive abilities will
improve balance, coordination, and posture and
enable the body to adapt to its surroundings without
consciously thinking about movement.
 Thus, it becomes important to train the nervous
system efficiently to ensure proper movement
patterns, which enhances performance and
decreases the risk of injury.
Sensory Receptors
 Specialized structures located throughout the body,
designed to transform environmental stimuli (heat, light,
sound, taste, and motion) into sensory information that
the brain or spinal cord can interpret to produce a
response:
– Mechanoreceptors respond to mechanical forces
(touch and pressure).
– Nociceptors respond to pain (pain receptors).
– Chemoreceptors respond to chemical interaction
(smell and taste).
– Photoreceptors respond to light (vision).
• For relevance to this course, we will focus attention on the
mechanoreceptors.
Mechanoreceptors
 Muscle spindle: Sensitive to change in length and
rate of length change in muscle.
 Golgi tendon organ: Sensitive to changes in
muscular tension and rate of tension change.
 Joint receptors: Respond to pressure, acceleration,
and deceleration of the joint.
Reflexes: Stretch Reflex
Muscle spindles
 Sensory receptors (called
intrafusal fibers) lie parallel to
the muscle fibers.
 Receptors responds to change
in length and rate of change in
length of the muscle.
 Reflexive response causes
contraction of the agonists.
 Causes stretch reflex,
generally due to excessive rate
of change in muscle length.
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Reflexes: GTO
Golgi tendon organs
 Sensory receptors located
in the muscle-tendon
junction
 Responds to muscle
tension.
 Reflexive action causes
inhibition of agonist (a.k.a.
autogenic inhibition).
 Due to perception that
tension puts the tendon at
risk (i.e. could rupture the
muscle from the bone)
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Neurological Properties of Stretching
Autogenic inhibition: the activation of a Golgi tendon organ
(GTO) inhibits muscle spindle response
 Initially, a low-force, long-duration (static) stretch stimulates lowgrade muscle spindle activity and temporarily increases muscle
tension.
 Muscle spindles become desensitized as the stretch continues.
 After 7 to 10 seconds, the increase in muscle tension activates the
GTO response, inhibiting muscle spindle activity and allowing further
muscle stretching.
 Holding the stretch beyond 10 seconds stresses the collagen fibers,
causing plastic deformation and lengthening the tissue (creep).
 When the stretch ends, muscle spindles reestablish their threshold.
Neurological Properties of Stretching (cont.)
Reciprocal inhibition
 Active stretching: the muscle on one side of a joint (i.e.,
the agonist) coincides with neural inhibition of the
opposing muscle on the other side of the joint (i.e., the
antagonist) to facilitate movement.
 Example: While performing a supine hamstring stretch,
contraction of the hip flexor muscles on the leg being
stretched will produce more active hip flexion, resulting in
reciprocal inhibition of the hamstring muscle group,
allowing them to be stretched further.
Physical Activity and the Nervous System
 Early stage improvements to physical activity are
largely due to changes in the way the CNS and PNS
coordinate movement.
 Unsuccessful activity can be modified with sensory
input to improve performance.
 Understanding the importance of neural input can
also help clients achieve appropriate flexibility by
utilizing some general neurological principle so to
enhance range of motion.