3. Movement

Question 1

Skeletal muscles

Answer 1

Muscles attached to bones. Majority of muscles. Two types: flexors and extensors

Question 2

Flexors

Answer 2

Muscles that bend a joint

Question 3

Extensors

Answer 3

Muscles that straighten a joint

Question 4

Agonists

Answer 4

Muscles that promote a movement

Question 5

Antagonists

Answer 5

Muscles that oppose a movement

Question 6

How do muscles carry out skilled, rapid movements?

Answer 6

Started by agonists and stopped by antagonists. Allows limb to accelerate and halt with great speed and precision

Question 7

How do muscles stabilize movement

Answer 7

Agonists and antagonists contract at same time (co-contraction)

Question 8

How are muscle fibres controlled?

Answer 8

By an alpha motor neuron that originates in the spinal cord or brain

Question 9

Motor unit

Answer 9

Alpha motor neuron + muscle fibres. Critical link between muscles and CNS

Question 10

Reflexes

Answer 10

Sterotyped, automatic muscle responses to particular stimuli. Involve the activation of sensory receptors. Rapid and occur without brain’s involvement. Depend on circuits in or near spinal cord

Question 11

Knee jerk response

Answer 11

Stretch (myotatic) reflex that occurs when tendon below knee is struck. Produces a slight stretch of the knee extensor muscle, which is sensed by receptors within the muscle called muscle spindles. Spindles stimulate sensory neurons which send impulses to spinal cord. Signals activate alpha motor neurons that cause stretched extensor muscle to contract, triggering the reflex. At same time, the antagonist flexor muscle relaxes. Allows you to “stick a landing”

Question 12

Flexion withdrawal reflex

Answer 12

Protective reflex that occurs when foot touches a sharp object. Pain receptors send message to spinal cord, alpha motor neurons are activated, leg is lifted (flexion). At same time, because body weight must be supported on other leg, extensors on opposite leg are activated (flexion crossed extension reflex)

Question 13

Muscle spindles

Answer 13

Provide feedback to brain about where various body parts are and how they’re moving during movement.

Question 14

Gamma motor neurons

Answer 14

Adjusts sensitivity of system, keeps muscle spindles taut

Question 15

Golgi tendon organs

Answer 15

Receptors where muscles connect to tendon, detect how much force/tension is applied to muscle. Increases precision

Question 16

Where are rhythmic patterns of muscle activations generated?

Answer 16

Spinal cord and brainstem

Question 17

Motor cortex

Answer 17

Controls activation of alpha motor neurons

Question 18

Regions of brain (in addition to motor cortex) that influence activity of motor neurons

Answer 18

Basal ganglia, thalamus, cerebellum, neuron groups in midbrain and brainstem

Question 19

Two pathways in which basal ganglia are involved

Answer 19

One facilitating desired motor program while other suppresses unwanted actions

Question 20

Dysfunction of basal ganglia in Parkinson’s

Answer 20

Degeneration of neurons in substantia nigra, whichh relay signals to basal ganglia using dopamine.

Question 21

Dysfunction of basal ganglia in Huntington’s

Answer 21

Loss of inhibitory neurons in basal ganglia results in uncontrolled jerking

Question 22

Critical neurotransmitter in movement

Answer 22

Dopamine

Question 23

Role of cerebellum in movement

Answer 23

Receives and integrates sensory input from receptors and cerebral cortex to ensure proper timing of muscle action. Allows for adaptation. Role in motor learning. Helps recalibrate movements as our bodies change

Question 24

Common cause of cerebellar degeneration

Answer 24

Long-term alcohol abuse