Transcript unit 10 Prop and Kin sense

Proprioceptors and the
Kinesthetic Sense
Proprioceptors and the Kinesthetic Sense
• If you are going to be successful in any performance
context, you must be able to coordinate your motor
performance.
• In order to do this, you have to be aware of the position
of the different parts of your body as well as be able to
keep your balance.
• You must have a sense of where your body is in relation
to the environment and where all your various body parts
are in relation to each other.
• This sense of your body is called your kinesthetic sense
(a sense of yourself in motion) and it is critical for the
learning and performance of perceptual-motor skills.
• Your kinesthetic sense relies on a system of sensory
receptors called “proprioceptors.”
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Structure and Function of the
Proprioceptors
• A system of specialized receptors called
proprioceptors provide your central nervous system
with critical information for balance and body
awareness.
• These receptors are located in the muscles, tendons and
joints.
• These proprioceptors keep your brain informed about
what is happening to your body.
• Proprioceptors are mechanoreceptors because they
require mechanical stimuli for activation.
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Muscle Spindles
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The Muscle Spindles
• Scattered throughout all of your skeletal muscles are tiny stretch
receptors, the muscle spindles.
• Muscle spindles provide information about muscle length.
• Muscle spindles lay parallel to the muscle fibers.
• When a muscle is stretched, its length changes.
• Muscle spindles activates when muscle lengthens (due to potential
danger).
• When muscle reaches a certain length, muscle spindles tell the
nervous system to contract muscle to prevent further stretching –
prevents against muscle damage.
• The more quickly the stretch/length change, the more rapid the
firing of impulses.
• In this way, the muscle spindles can report on the velocity (speed)
of muscle activity as well as the extent of the stretch achieved
during muscle activity
• When the muscle contracts, it is called the point of bind (POB). 5
The Golgi Tendon Organ
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The Golgi Tendon Organs
• Changes in tendon length and tension are detected by Golgi tendon organs.
• The tension increases within a tendon as a result of muscle contraction.
• The tension stimulates a Golgi tendon organ that then sends signals to the
spinal cord and cerebellum to inform them about the contraction state of the
muscles.
• As the contraction of a muscle becomes stronger, the tension becomes greater
and the rate of stimulation of the tendon organ increases.
• In this way, the tendon organ can inform the central nervous system of the
strength of muscle contraction.
• When POB is reached, stretch is held for 10 seconds, after which the muscles
relaxes and pain disappears.
• Golgi Tendon Organs brings about relaxation.
• Golgi Tendon Organs sense muscle tension, and sense when there is no danger
of damage and override muscle spindles – cause muscle to relax.
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Specialized Joint Receptors
• Special receptors in the joints signal changes in joint
position.
• This information allows you to be aware of positions
of all of your various body parts.
• It also informs you when there are changes in any
positions.
• These receptors are stimulated when there is movement
in a joint.
• There are three different types of joint receptors.
• The most common are the spray-type of Ruffini
endings, similar to those found in the skin.
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Specialized Joint Receptors
• As the joint capsule is distorted with movement, these
receptors can report the rate, direction and extent of
movement in a joint.
• A second type of joint receptor is similar to the Golgi
tendon organ.
• It is located in the ligaments surrounding the joint and is
stimulated by ligament stretch and tension.
• A modified kind of Pacinian corpuscle is the third type of
joint receptor.
• These receptors are stimulated by pressure in connective
tissue arising from the movement of the joint.
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How Proprioceptors Work
• Muscle spindles are primarily involved with providing
information for reflex movements,
• Their sensory pathway is to the spinal cord, where they
can be directly associated with the command for an
adjustment in movement patterns.
• Because the sensory fibers from Golgi tendon organs
that go to the spinal cord synapse (In the nervous
system, a synapse is a structure that permits a neuron to
pass an electrical or chemical signal to another cell) with
interneurons, communication with the thalamus and
sensory cortex becomes possible.
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How Proprioceptors Work
• Joint receptors operate in teams, with one team monitoring joint
movement through a 10-15 degree range, another team will take
over for the next 10-15 degrees.
• Since receptor teams are sensitive to different angles, the entire
movement of that joint is covered because each team fires during
their own part of the range of movement.
• If movement is stopped at a certain joint angle, the receptors team
responsible in that range will continue sending impulses to the
central nervous system indefinitely.
• In addition to being able to report the angle of the joint position,
receptors also are able to report the speed (velocity) of joint
movement.
• The rate at which they send impulses increases as the speed of joint
movement increases.
• Information about joint position is sent to the cerebellum, as well
as to the thalamus and on to the sensory cortex.
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PRACTICALS
• Practical Exam
• Four in a group.
• Each member needs to know how to catch a
ball, how to bad and ball and how to field.
• Members of the group will be rotated after 2
rounds.
• Will be held on the Veld-en-Vlei Sport
Complex.
• Date: 08/10/12 and 15/10/12
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Proprioceptive Skills and the
Kinesthetic Sense
• Information gathered from the proprioceptors is sent to the
spinal cord, all parts of the brainstem, the cerebellum as well
as the sensory cortex where it is put together to form
perceptions about your body that we generally refer to as
your kinesthetic sense.
• Your kinesthetic sense or your "sense of your body in
motion" is a result of the information you derive from your
proprioceptors.
• This "sense of your body as you move needs to be integrated
with visual and auditory information to form a complete and
accurate perception of movement situation.
• The following proprioceptive skills (kinesthetic abilities) are
important for motor skill performance.
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1. Body Awareness
• Body awareness involves your sense of the
relation of your body parts to one another, and
the rate at which they are moving (if they are
moving).
• Body awareness includes your understanding of
the extent of a movement pattern as you
perform it.
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2. Spatial Awareness
• Spatial awareness is your awareness of how quickly and
in what direction you are moving.
• You could be moving forward, backward, left, right, up,
down, on a rotational path, etc.
• Different body parts also move in different directions
and at different speed during motor skill performance.
• Your sense of where all the different parts of your body
are in space is your spatial awareness.
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Body Awareness
Throwing the javelin
• Throwing the javelin
provides a challenge
to your body awareness,
since it
requires you to do a
variety of different
movements with your
arms and legs,
including a twisting of
your trunk
and a cross-over step.
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Spatial Awareness
Blocking at the net
• Blocking at the net in
volleyball provides
a challenge to your spatial
awareness.
You must know where you
are jumping
in relation to the net, get
your arms
fully extended, and land on
your
own side of the court.
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Body Awareness and Spatial Awareness combine to
give you a sense of where all your body parts are and
how you are using the space around you
• In the high jump, you
must have a body
awareness of the
relationship among your
arms, legs, head and
trunk,
• as well as a spatial
awareness
of moving upward and
backward.
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Body Awareness and Spatial Awareness combine to
give you a sense of where all your body parts are and
how you are using the space around you
• When volleying a soccer
ball, you must
have sufficient body
awareness to create
a balanced body shape in the
air,
• and a spatial awareness of
the horizontal flight
of your body toward the ball
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