Neural Control of Movement

1. Neural Control of Movement • Chapter 2

2. CENTRAL NERVOUS SYSTEM • Brain • Cerebral Cortex/Cerebrum • Motor cortex • Basal Ganglia/Diencephalon – sensory input • Cerebellum – motor control • Brain stem – sensory input • Spinal Cord

3. CENTRAL AND PERIPHERAL NERVOUS SYSTEM • Central nervous system • Peripheral nervous system

4. PERIPHERAL NERVOUS SYSTEM • Somatic • Sensory (Afferent) Neuron • Motor (Efferent) Neuron • Autonomic [FYI] • Parasympathetic • Sympathetic

5. SENSORY NEURONS • Carry impulse towards the CNS Towards CNS

6. MOTOR NEURONS • Carry impulse away from the CNS (e.g. motor nerves) • Stimulatory • Inhibitory

8. Spinal Nerves • Cervical spinal nerves (C1 to C8)These nerves (eight pairs) supply the back of the head, the neck and shoulders, the arms and hands, and the diaphragm. • Thoracic spinal nerves (T1 to T12)These nerves (12 pairs) supply the chest, some muscles of the back, and parts of upperabdomen. • Lumbar spinal nerves (L1 to L5)These nerves (five pairs) supply parts of the lowerabdomen and the back. • Sacral spinal nerves (S1 to S5)These nerves (five pairs) supply the thighs and parts of lowerlegs, and the feet.

10. NEURON ANATOMY • Dendrite • Cell Body • Axon

11. NEURON ANATOMY • Neuron • …a single nerve cell • Nerve • ….a bundle or group of neurons • A nerve contains both motor and sensory neurons

12. Proprioception and Kinesthesis • What is kinethesis? • …awareness of the position and movement of the body • What is proprioception? • …ability to regulate posture and movement by responding to stimuli from receptors throughout the body

13. MUSCLE SPINDLES

16. 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

17. GOLGI TENDON ORGAN

19. GOLGI TENDON ORGAN • 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

20. Other Receptors • Proprioceptors of the joints and skin • Examples: Meissner’s corpuscles, Ruffini’s corpuscles, Pacinian corpuscles, Krause’s end-bulbs

22. NEUROMUSCULAR CONCEPTS

23. Motor Unit • One motor neuron and all the muscle fibers it innervates • All-or-none principle

24. Factors Affecting Muscle Tension • The number of motor units activated • Type of motor units activated (fast or slow twitch) • The frequency of stimulation of the motor units

25. Factors Affecting Muscle Tension • Stimulation • Subthreshold stimulus • Threshold stimulus • Submaximal stimulations • Maximal stimulation

26. Factors Affecting Muscle Tension • Twitch • Summation • Tetanus

27. Neuromuscular Summary • An example from baseball. • A pitcher throws a curve ball to Derrek Lee • Derek’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

28. 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 Derrek 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

29. 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) • Remember, each nerve ending stimulates a separate muscle fiber

30. Neuromuscular Summary • 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

31. 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 lift the 150 lb