Essay by TEE25A+, March 2003

download word file, 3 pages 3.0


Key Terms and Concepts

The Control of Movement

1. Muscles and their movements

Categories of muscle


Skeletal or striated


Precise movements: few muscle fibers innervated by each axon

Neuromuscular junction


Muscle contraction

Antagonistic muscles



Myasthenia gravis

Autoimmune attack on acetylcholine receptors at neuromuscular junctions

Progressive weakness and rapid fatigue

Depletion of acetylcholine after several action potentials in rapid succession


Drugs that suppress immune system

Drugs that inhibit acetylcholinesterase (enzyme that breaks down acetylcholine)

Prolongs action of acetylcholine

Fast and slow muscles


Red, slow, resistant to fatigue

Pink, intermediate speed, moderately resistant to fatigue

White, fast, forceful, fatigue quickly

Birds: white and dark muscles

Humans and other mammals: mixed fibers in each muscle

Fast-twitch fibers

Slow-twitch fibers

Muscle control by proprioceptors

Stretch reflex

Muscle spindle

Stretch receptor parallel to muscle

Causes muscle to contract: decreases stretch

Golgi tendon organ

In tendons at opposite ends of muscle

Inhibits muscle: brake against too vigorous contraction

Location of body parts

Units of movement

Voluntary and involuntary movements

Reflexes: consistent automatic responses to stimuli


Many behaviors: mixture of voluntary and involuntary influences

Movements with different sensitivity to feedback

Ballistic movement: executed as a whole; cannot be altered after initiated

High sensitivity to feedback

Threading needle


Delayed auditory feedback

Infant reflexes

Grasp reflex

Babinski reflex

Rooting reflex

Cerebral cortex damage in adults à infant reflexes released from inhibition

Allied reflexes: several reflexes elicited together

Sequences of behaviors

Central pattern generators

Rhythmic movements

Frequency of repetition: governed by spinal cord

Motor program: fixed sequence of movements

Learned or built in

Birds: wing extension when dropped

Humans: yawning

Categories of movement

Spinal motor neuron: final common path

Many brain areas control different patterns

Brain Mechanisms of Movement

1. The role of the cerebral cortex

Primary motor...