1. The Nervous System and the Control of Movement

2. Two Components CNS (Central Nervous System) brain and spinal cord
2. PNS (Peripheral Nervous System)
12 pairs of cranial nerves and 31 spinal nerves

3. CNS
The brain: receives and interprets signals sent from other parts of the body
6 major parts
Cerebrum
Largest
sensory and motor activities AND intelligence
Divided into frontal, temporal, parietal and occipital lobes
Cerebellum
2nd largest
movement and balance

4. Link between spinal cord and cerebellum
Brain Stem
Link between spinal cord and cerebellum
Posture, muscle tone, eye movement (autonomic functions)
Diencephalon
Between cerebrum and brain stem
Thalamus and hypothalamus
Thalamus: pain, screens signals, attention
Hypothalamus: body temp., appetite, emotions
other automatic function

5. Limbic System
Structures in cerebral hemispheres
Regulates drives (hunger, aggressions etc.)
Reticular Activating System
Network of neurons
Maintaining consciousness

8. The Spinal Cord: main pathway for messages and connects brain to PNS
Travels down vertebral column to 2nd lumbar vertebrae
Adults 42cm-45cm long
Spinal nerves exit between vertebrae
Carries sensory info. to brain and motor info. away from brain

9. PNS Recall; 31 pairs of spinal nerves and 12 pairs of crainial nerves
- nerves have two roots
1. anterior root: carries motor
nerve fibres (efferent)
2. posterior root: carries sensory
nerve fibres (afferent)

10. PNS 2 Components Autonomic Nervous System
Controls involuntary contraction
2 Subsystems
1. Sympathetic System
- causes localized body
adjustments to occur (sweating
or cardiovascular changes)
- prepares the body for
emergencies (fight/flight)
2. Parasympathetic System
- returns body to normal after
sympathetic response

12. Somatic Nervous System
Awareness of external environment
Afferent and efferent nerve fibres
Info from receptors in the skin, voluntary muscles, tendons and joint
Gives sensations in touch, pain, heat….
Movement
See pg. 97 Figure 6.2

13. Reflex Arc
Reflexes: automatic and rapid responses to particular stimulation Reflex Arc: the pathway along which the initial stimulus and the correcting response message travel cerebral reflex- command center in brain spinal reflex- command center in spinal cord

14. Autonomic reflexes
mediated by autonomic division of nervous system
Smooth muscle, cardiac muscle, glands
Somatic reflexes
mediated by somatic division of nervous system
Stretch and withdrawal reflex (ways the body responds to unexpected

15. 5 Parts of a Reflex Arc
Receptor: receive the initial stimulus (pinprick/loud noise)
2. Sensory (afferent) nerve: sends impulse to spinal cord or brain (afferent neuron of muscle spindle or tendon organ)

16. Intermediate Nerve Fibre: interprets the signal and issues an appropriate response (interneuron)
Motor (efferent) nerve: carries response from spinal cord to muscle organ
Effector organ: carries out the response (skeletal muscle moves)

17. Proprioceptors and Control of Movement
Provide sensory information about the state of muscle contraction, the position of body limbs, body posture and balance
Located in tendons, muscles, and joints
Two sensory receptors:
Golgi tendon organs
Muscle spindles

18. Golgi Tendon Organs
- sensory receptors that terminate where tendons join to muscle fibres
Used to detect tension exerted on tendon
1 sensory nerve, 1 motor nerve
Play a part is strength and power development
Muscle Spindles
sensory receptors that lie parallel to main muscle fibres
Send constant signals to spinal cord
2 sensory nerve, 1 motor nerve
Help maintain tension and sensitive to muscle length
Play a part in all physical movement as they constantly and automatically adjust to the changing demands placed on them

19. The Stretch Reflex Simplest spinal reflex Monosynaptic reflex
e.g knee jerk
Receptor muscle sense the action (e.g hammer on knee)
Message sent along afferent nerve axon to spinal cord
Afferent synapses with efferent of same muscles
Impulse in transmitted along efferent pathway
Motor unit contracts (e.g. knee jerk occurs)

20. Reciprocal Inhibition:
- when one agonist muscle contracts, antagonist muscle is simultaneously inhibited
Provides constant adjustment

21. Polysynaptic Reflexes
One of more interneurons lie between primary sensory fibres and motor neurons
Increased complexity and slower
e.g. withdrawal reflex
From pain
Sensory neuron to interneuron to motor neuron

22. Homework:
From last nights reading,
Outline the sequence the Polynaptic Cross-Extensor Reflex
Complete exercise 6.6 and be ready to discuss tomorrow