unit 9 Control of Body Movements

Question 1

Types of proprioceptors and their actions: Golgi Tendon Organs (GTOs)

Answer 1

located at junctions of tendons and muscle fibres

consist of nerve endings attached to bone that monitor muscle tension (esp during isometric contractions_

when increased tensions= activate GTO’S = less active fibre= relaxation

Question 2

Types of proprioceptors and their actions: muscle spindles

Answer 2

detects muscle stretch and it’s length

made of several skeletal muscle cells called intrafusal fibres

Question 3

intrafusal fibres

Answer 3

centre region= not contractible (lack myosin and actin) wrapped in dendrites of 1st order

ends of fibres= have actin and myosin and are innervated by gamma motor neurons and can contract

generates most force and are larger/main fibre

Question 4

alpha-gamma co-activation

Answer 4

1. alpha motor neuron fires, gamma motor neuron fires
2. muscle and intrafusal fibres both contract
3. stretch in centres of intrafusal fibres unchanged. firing rate of sensory neuron remains constant

Question 5

properties of skeletal muscle: myotatic unit:

Answer 5

collection of neural pathways controlling. single joint and antagonist and agonist

includes the sensory, alpha lower neuron, and the interneurons connected to them

Question 6

properties of skeletal muscle: reciprocal inhibition

Answer 6

inhibition of contraction in antagonist at the same time agonist contract

directly w/ the alpha lower motor neuron that innervates the agonist (excitatory synapse)

Question 7

excitatory vs inhibitory interneuron

Answer 7

1. carries signal to alpha motor neuron that goes into agonist
2. prevents signalling alpha motor neurons going to the antagoinist to allow agonist to contract

Question 8

what is something reciprocal inhibition not have

Answer 8

efferent. (stimulus and receptor= same, response is opp)

Question 9

levels/phases of motor control: level 1

Answer 9

planning movement you are unconsciously about to do

involves the premotor cortex and association areas of the brain

receives input from cerebellum and basal nuclei

signals to primary motor cortex which contains upper motor neurons (synapse w/ lower MN and those synapse w/ muscle)

Question 10

levels/phases of motor control: level 2

Answer 10

initiating movement (primary motor cortex)

contains cell bodies of upper MN that are mapped to control skeletal cells in specific regions of the body

stimulation of the upper MN by the planning areas creatse signals that travel via the corticospinal tract into brainstem or spinal

they synapse w/ lower MN that innervate skeletal muscle

Question 11

levels/phases of motor control: level 3 brainstem nuclei

Answer 11

some contain cranial nerves (location where synapses are)

others contains cell bodies of upper MN responsible for coordination of large muscle groups used to maintain posture and locomotion

Question 12

levels/phases of motor control: level 4 spinal cord

Answer 12

contains cell bodies of alpha motor neurons

contains networks of neurons that form central pattern generators (CPGs)

network of oscillating inhibitory/excitatory neurons that create units responsible for rhythmic contraction and relaxation of flexor and extensor muscles at a joint

these networks allow repetitive movements.

Question 13

for level 4 spinal cord how do we start/ stop movement

Answer 13

signals from the cortex needed to stop/start signal

CPG’s (central pattern generators) maintain it once it’s going

Question 14

levels/phases of motor control: 5- cerebellum

Answer 14

Plans and inhibits movement

Stores planned movements and compares it to actual using sensory input from sources like proprioceptors and correct if needed

Question 15

levels/phases of motor control: 6 basal nuclei

Answer 15

Aid in planning movement

Surpass unwanted motion (esp when at rest and bot moving)

Damage to this= movement disorders like parkinsons and hun

Question 16

levels/phases of motor control: 7 corticospinal (direct) pathway

Answer 16

Signals from the cortex to the skeletal muscle

Question 17

What is cerebellum affected by

Answer 17

Drugs/alcohol- uncoordinated movement

Question 18

How does upper mn signal to lower mn

Answer 18

Uses neurotransmitter glutamate

Question 19

Destruction of upper Mn

Answer 19

Spinal reflex arc still present since lower alpha MN and sensory neuron synapse still intact

Question 20

Destruction of upper Mn: spastic paralysis

Answer 20

Muscle tone increases, no atrophy of muscles- no signals from brain

Question 21

Destruction of upper Mn: exaggerated reflex

Answer 21

Like knee jerk reflex

Caused by lack of inhibitory signals from brain which makes reflexes stronger than usual

Question 22

Destruction of lower alpha MN

Answer 22

Spinal reflex arc= absent

Question 23

Destruction of lower alpha MN: flaccid paralysis

Answer 23

Signals from brain/sensory neurons cannot reach muscle

Decrease muscle tone and atrophy of muscle

Question 24

Destruction of lower alpha MN: complete loss of reflexes in affected area

Answer 24

Can’t stimulate muscle when it receives signals from sensory neurons