1. Chapter 6: Movement

2. Three Kinds of Muscle Fibers 1. Smooth 2. Skeletal (striated) 3. Cardiac

3. More about Fibers 1. Each muscle in our bodies is made up of thousands of muscle fibers 2. A motor neuron may innervate several hundred individual fiber or just a few fibers  What would you guess about differences in muscular control between these two types of innervation?  Where do you think you might see small innervation ratios vs. larger ratios?

4. Relationship of Muscles to Each Other 1. Antagonistic pairs  Consists of a flexor muscle and an extensor muscle  Biceps and triceps are the best example

5. Antagonistic Pair

6. Neurotransmitter Control of Muscles 1. Neuromuscular junctions 2. Neurotransmitter: acetylcholine (ACh) 3. ACh release always causes a muscular contraction

7. Slow and Fast Twitch Fibers 1. Some animal species have separate ‘speeds’ of muscles 2. Humans have different speeds of fibers as well, but they aren’t distinct groups  Fast twitch fibers = anaerobic  running  Slow twitch fibers = aereobic  talking

8. How do muscles ‘know’ what they are doing? 1. Our old friend the proprioceptor 2. These receptors control muscular reflexes 3. There are two kinds of proprioceptors:  muscle spindle  Golgi tendon organ

9. Proprioceptors

10. Types of Movement 1. Voluntary movement 2. Involuntary or reflexive movements  You are born with at least 10 reflexive  Ballistic movements 3. A motor program is a sequence of coordinated, separate movements that occur together – animals and humans both have them

11. Movement in the Cortex  Primary motor cortex is used to direct voluntary, complex movements  Just like with the somatosensory cortex, there is a map of the body on the cortex

12. Other areas in the Cortex  premotor cortex  supplementary motor cortex

13. From the Brain to the Cord 1. There are two distinct tracts of information running through the spinal cord  Dorsolateral tract  Ventromedial tract 2. Most movements require activity of both tracts 3. Cross-over (for contralateral control) occurs in the brainstem

14. The Cerebellum 1. The cerebellum (where is that again??)  coordination 2. Rats with cerebellar damage would have a hard time grooming itself, humans…

15. The Basal Ganglia 1. The basal ganglia are a group of subcortical forebrain structures 2. These structures are also involved in deciding when and when not to move 3. People with OCD have over-activity in the basal ganglia = may be involved in habit formation  More notes in class following group activity.