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Neural Anatomy and Function. NERVOUS SYSTEMS. Central nervous system Peripheral nervous system. CENTRAL NERVOUS SYSTEM p. 33. Brain Cerebral Cortex/Cerebrum Motor cortex Basal Ganglia/Diencephalon – sensory input Cerebellum – motor control Brain stem – sensory input Spinal Cord.

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Nervous systems
NERVOUS SYSTEMS

  • Central nervous system

  • Peripheral nervous system


Central nervous system p 33
CENTRAL NERVOUS SYSTEM p. 33

  • Brain

    • Cerebral Cortex/Cerebrum

      • Motor cortex

    • Basal Ganglia/Diencephalon – sensory input

    • Cerebellum – motor control

    • Brain stem – sensory input

  • Spinal Cord


Peripheral nervous system
PERIPHERAL NERVOUS SYSTEM

  • Somatic

    • Sensory (Gamma) Nerves

    • Motor (Alpha) Nerves

  • Autonomic [FYI]

    • Parasympathetic

    • Sympathetic



Nerve anatomy
NERVE ANATOMY

  • A single nerve cell is called a neuron

  • A bundle or group of neurons make up a nerve

  • A nerve contains both afferent and efferent nerves


Afferent neuron
Afferent Neuron

  • Carry impulse towards the CNS (e.g. sensory nerves)

  • Synapse

Towards CNS


Efferent neuron
Efferent Neuron

  • Carry impulse away from the CNS (e.g. motor nerves)

  • Stimulatory

  • Inhibitory


Neuron anatomy
NEURON ANATOMY

  • Dendrite

  • Cell Body

  • Axon


AXON

  • Conduction

  • Myelin sheath

  • Synapse

  • Neurotransmitter


Conduction
CONDUCTION

Resting State: Na outside, K inside


Conduction1
CONDUCTION

4. Na K Pump

1. Depolarization

3. Repolarization

2. Propagation





Synapse1
SYNAPSE

  • Quick Time Movie




Motor unit
MOTOR UNIT

  • Motor unit = one motor nerve + all the muscle fibers it innervates.

  • Types

    • Fast (alpha -1)

    • Slow (alpha -2)


3

1

2


Motor unit1
MOTOR UNIT

Fast Fast Slow


Muscle tension or force or strength
MUSCLE TENSION or FORCE or STRENGTH

  • Number of MU stimulated

  • Frequency of stimulation to each MU

  • Type of MU stimulated


Muscle stimulation how does it begin
MUSCLE STIMULATION: How does it begin?


Volitional control motor cortex
Volitional Control (Motor Cortex)

  • Motor cortex

  • Motor neurons

  • Muscles


2 reflex control
2. Reflex Control

  • Afferent neuron

    • Sensory neuron

  • Efferent neuron

    • Motor neuron


Proprioception kinesthesis p 37
PROPRIOCEPTION & KINESTHESISp. 37

  • Proprioception

    • The ability to sense the position and location and orientation and movement of the body and its parts

  • Kinesthesis

    • The ability to feel movements of the limbs and body


Proprioception
PROPRIOCEPTION

  • Proprioceptors of the joints and skin

    • Meissner’s corpuscles

    • Ruffini’s corpuscles

    • Pacinian corpuscles

    • Krause’s end-bulbs


Proprioception1
PROPRIOCEPTION

  • Proprioceptors of the muscles

    • Muscle spindles

    • Golgi tendon organs


Muscle spindles
Muscle Spindles



Muscle spindles1
Muscle Spindles

  • Provide proprioception

  • Sense the amount of stretch and the rate of stretch

  • Reflexes involving the muscle spindles is how we ‘feel’ a movement was done correctly

  • Spindles are a part of learning; we develop such reflexes as we practice skills and movements



Golgi tendon organs1
Golgi Tendon Organs

  • Sensitive to muscle tension and active contraction

  • Protect muscle from excess contraction force

  • Stimulation of GTO an afferent impulse is sent to the central nervous system

  • In turn, efferent impulses are sent to the…

    • Agonist muscle causing it to relax

    • Antagonist muscle causing it to contract


Neuromuscular summary
Neuromuscular Summary

  • An example from baseball.

  • A pitcher throws a curve ball to Sammy Sosa

  • Sammy’s eyes see the ball coming towards him and is able to identify the pitch as a curve ball

  • Sensory nerves (afferent) send that information to the CNS

  • In the CNS the sensory nerve synapses with motor nerves

  • The motor nerves in turn stimulates the muscles (deltoid and pectoralis major) required to swing the bat in the proper position to hit the ball


Neuromuscular summary1
Neuromuscular Summary

  • Inside the fibers of the deltoid and pectoralis major, calcium is released

  • The calcium allows myosin heads to attach to actin

  • When the heads swivel the fibers of the deltoid muscle will shorten

  • The shortening of the fibers will pull on the humerus causing Sammy to swing the bat

  • The muscle spindles “tell” the CNS when the arm is in the correct position

  • If all goes as planned, the deltoid and pectoralis major will move his arms into a position to hit the ball


Neuromuscular summary2
Neuromuscular Summary

  • An example from weight training.

  • A man is having his muscular strength tested on the bench press

  • For his first lift, 50 pounds is put on the bar

  • He will be using his pectoralis major muscle with has 500 motor units (300 slow twitch and 200 fast twitch) and his triceps muscle

  • His CNS stimulates 280 motor units leading to his pectoralis major muscle (180 slow twitch and 100 fast twitch)

  • End nerve ending stimulates a separate muscle fiber


Neuromuscular summary3
Neuromuscular Summary

  • Calcium is released, myosin attaches to actin and swivels.

  • The pectoralis major and triceps muscles shortens and his arm extends outward raising the bar with 50 pounds on it.

  • After a few minutes of rest, 100 pounds is place on the bar

  • This time he stimulates 380 motor units (260 slow twitch and120 fast twitch)

  • The weight is successfully lifted

  • After a few minutes of rest, 150 pounds is place on the bar


Neuromuscular summary4
Neuromuscular Summary

  • This time he stimulates 460 motor units (280 slow twitch and 180 fast twitch)

  • As the pectoralis major muscle contracts the GTO in the pectoralis major are stimulated

  • They stimulate a sensory nerve leading to the CNS

  • In the CNS, the sensory nerve synapses with a motor nerve that will inhibit (relax) the pectoralis major muscle

  • The man is unable to successfully lift the 150 pounds.


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