Movement

**The eyes, the organs of balance, and the receptors in skin, muscles, and joints**

monitor the body’s responses, and they feed their information back into sensorimotor circuits.

**ballistic movements**

brief, all­or­none, high­speed movements, such as swatting a fly,not influenced by sensory feedback

**Association cortex**

is at the top of the sensorimotor hierarchy.

Two major areas of sensorimotor association cortex:

the posterior parietal association cortex

the dorsolateral prefrontal association cortex.

**The posterior parietal association cortex** directs

behavior by providing spatial information, and in directing attention

It receives information from the three sensory systems:

the visual system,

the auditory system

the somatosensory system

**The dorsolateral prefrontal association cortex** receives

projections from the posterior parietal cortex - sends projections to areas of secondary motor cortex -to primary motor cortex - to the frontal eye field.

Areas of secondary motor cortex

receive much of their input from association cortex and send much of their output to primary motor cortex

Mirror neurons

neurons that fire when an individual performs a particular goal directed hand movement or when they observe the same goal directed movement performed by another

The primary motor cortex

is dedicated to controlling parts of the body that are capable of intricate movements, such as t__he hands and mouth__

The cerebellum and the basal ganglia interact

with different levels of the sensorimotor hierarchy and, in so doing, coordinate and modulate its activities

Cerebellum

motor learning, particularly in the learning of sequences of movements

basal ganglia

habit learning

Neural signals are conducted from

the primary motor cortex to the motor neurons of the spinal cord over four different pathways.

Two pathways descend in the

dorsolateral region of the spinal cord(dorsolateral motor pathways)

and two descend in the

ventromedial region of the spinal cord—(ventromedial motor pathways)

Motor units

the smallest units of motor activity

**A skeletal muscle**

comprises threadlike muscle fibers bound together in a tough membrane and attached to a bone by a tendon.

Acetylcholine

activates the motor end-plate on each muscle fiber and causes the fiber to contract

Contraction

method that muscles have for generating force, muscle can generate force in only one direction

Fast muscle fibers

contract and relax quickly

Slow muscle fibers

slower and weaker, capable of more sustained contraction

**Flexors**

act to bend or flex a joint

**extensors**

act to straighten or extend a joint

Cocontraction

the simultaneous activation of muscles on opposite sides of a joint

Sensorimotor system

fundamentally plastic