Lecture 24

Question 1

What does voluntary movement require

Answer 1

Immensely complex neural interactions.
It involves intricate interactions between various regions of the brain, spinal cord, and peripheral nervous system, coordinating muscles and joints to execute precise actions.

Question 2

Prefrontal cortex

Answer 2

This is the Neurons involved in decision making and planning the desired movement outcome

Question 3

Permotor cortex

Answer 3

This is the neurons involved in organising movement sequences to achieve the octcome,
For example, walk to the stairs, climb 10 stairs down
So this is all about organising movement

Question 4

Primary motor cortex

Answer 4

• this is made of cell bodies of upper motor neurons
• this is the neurons involved in directing voluntary movement
  so for example: activate knee and hip flexors to step up…. And ect

Question 5

How do you plan movement and initiating movement

Answer 5

• prefrontal cortex - plan
• pre motor cortex - move
• motor cortex - telling the bones what to do

Question 6

Modifying movement: Basal Nuclei

Answer 6

• influences posture and automatic movements
• regulates muscle tone
• refines movements - selects which to allow and witch to inhabit, how they do this is they alter sensitivity of neurons projecting into the corticospinal or other pathways

Question 7

Modifying movement: cerebellum

Answer 7

• this stores and facillstes learning, planning and execution of motor programs ( eg: walking program )
• monitors and compares sensory inputs to compare actual movement to planned movement
• organises timing of muscle contractions and modifies ongoing activity

Question 8

Pathway from brain to muscle: Corticospinal pathway

Answer 8

So the upper motor neurons in the primary motor cortex fire action potentials that propagate along axons extending down the spinal cord to activate lower motor neurons in spinal cord, to fire action potentials that propagate along axons withen peripheral nerves to skeletal muscle

Question 9

What is a motor unit made out of

Answer 9

Single lower motor neuron plus all the skeletal muscle fibres in innervates

Question 10

Small motor unit

Answer 10

• a motor neuron plus the few muscle fibres it activates
• can produce more precise movement ( eg; hands lips, tounge )

Question 11

Large motor unit

Answer 11

• a motor neuron plus the many muscle fibres it activates
• can produce more forceful movements ( eg: of limbs )

Question 12

Voluntary movement: - response time

Answer 12

Voluntary responses to touch:
This includes complex neural processes that include the transmission of sensory information from the point of touch to the brain and the subsequent generation of motor response

• 100+ ms latency ( the point at how long it takes for the sensory signal to travel to the brain )
• high variable
• path : from foot to brain, then ti quadreps muscles
• focus and training can reduce response time as it reduces the number of neural connections involved

Question 13

Strech reflex - response time

Answer 13

Reflex response to tendon tap

• 30 - 40ma latency
• very consistent
• protects muscles from tearing
• path : from stretched muscle spindles to spinal cord to stretched muscle
• cannot be changed with training

Question 14

Strech reflex response - how it happens

Answer 14

• tendon tap causes sudden, fast stretch of quadriceps muscles
• muscle spindles ( proprioceptors/strech receptors withen the muscle ) gets stretched
• mechanically gated Na+ channels open in membrane and dendritic endings of the sensory neuron of the muscle spindle
• Na+ entry causes depolarisation that leads to an action potential which propagates along sensory axon to spinal cord
• synaptic transmission from sensory axon terminal causes depolarisation in motor neuron cell body
• AP fires and propagates along motor axon to NMJ of quadriceps
• stimulating quadriceps to contract, causing the foot to kick out

Question 15

Reflex response to painful stimuli

Answer 15

• Nociceptors activated
• sensory neuron depolarises and action potential fires and propagates to spinal cord
• sensory neurons stimulates inter neurons, leading to excitation of motor neurons that stimulate flexors and inhibition of motor neurons that stimulate extensors, enabling withdrawal of the affected limb