T2L4 motor learning and neurological syndromes

Question 1

simple motor pathway

Answer 1

motor cortex of brain&raquo_space;
upper motor neuron&raquo_space;
lower motor neuron&raquo_space;
muscle

upper motor neuron goes from the motor neuron cells down the midbrain, pons, medulla and spinal chord until it synapses to the lower motor neuron in the sc.

each branch of the lower motor neuron ends at a motor plate of a single muscle fibre

Question 2

s7

Answer 2

see s7 yaaaaaaaaa

Question 3

hierarchy of motor control

Answer 3

eg tennis serve

high level

• used for STRATEGY
• association areas of neocortex and basal ganglia
• planning direction, power, spin etc

mid level

• used for TACTICS
• motor cortex and cerebellum
• specific instructions to execute the serve as planned

low level

• used for DELIVERY
• brainstem and spinal chord
• getting the signals to the muscles

Question 4

descending motor pathways

Answer 4

s9

3 descending ventromedial pathways:

1. reticulo-spinal - extensor in arms and legs
2. tecto-spinal - head and neck movement
3. vestibulo-spina - head and neck movement

#. rubrospinal - flexor muscles in arms
these use sensory info about balance, position and visual environment to reflexively maintain balance and posture

Question 5

the corticospinal tract

Answer 5

• the only cortical tract to directly synapse with motor neurons
• brodmann area 4 and 6
• 90% fibres cross
• derived from cells in layer V of motor cortex

s11

Question 6

the rubrospinal tract

Answer 6

• unclear how used in humans

- innervates flexor muscles of upper limb

Question 7

vestibulospinal tract

Answer 7

looks like a weird octopus worms fucked up child

• originate at vestibular nuclei
• relay sensory info from vestibular labyrinth in inner ear
• projects down sc to cervical spinal circuits that control head and neck movements

KEEPS EYES STABLE AS BODY MOVES

• projects as far down as lumbar spinal chord. helps maintain balances and posture by facilitating extensor muscles in legs

see s13

Question 8

tectospinal tract

Answer 8

• originates at superior colliculus in midbrain
• receives input from retina and visual cortex
• construct map of world around us
• allows head and eyes to move so the right point is focused on by eyes
• projections are very short and close to the midline. muscles of neck, shoulders, upper trunk

Question 9

reticulospinal tract

Answer 9

• from brainstem
• reticular formation just under cerebral aqueduct and 4th ventricle
• EXTENSION OF LIMBS

pontine pathway- medial
medullary pathway- lateral

Question 10

posturing in coma

Answer 10

pain causes reflexes

1. decorticate posturing- lesion above red nucleus
   - rubrospinal are disinhibited so facilitate flexors
   - arms raised to head
   - arms bent
2. decerebrate posturing- lesion below red nucleus
   - rubrospinal are disrupted leading to extension
   - hands out at 90 degrees, arms straight

Question 11

damage to motor cortex and corticospinal tract

Answer 11

posture- some preserved upper limb flexion and lower limb extension

increase tone&raquo_space; spasticity
brisk reflexes
clonus

can maintain posture- arm is held up and bent and fist on one side, toes pointed upwards on foot of same side

eg stroke

Question 12

loss of descending inhibition

Answer 12

babinkski reflex

• extensor muscles in feet
• flayed toes

see s20

increased tone, spasticity
as altered excitability in spinal inhibitory interneurons

in contrast to motor neuron damage which leads to spasicity

Question 13

corticobulbar pathways

Answer 13

talking/swallowing/tongue

Question 14

stroke - facial palsy

lmn vs umn

Answer 14

umn lesion - bottom 1/4 of face
lmn lesion - whole half of face

see diagram s22
p interesting tbf

Question 15

primary motor cortex arrangements

Answer 15

arranged somatotopically- foot is next to leg next to trunk next to arm next to hand- see s24

eg parasagittal meningioma
- presses on foot/leg area of both cortices leading to bilateral leg weakness and spasticity

Question 16

blood flow to brain and stroke sydromes

Answer 16

see s26

Question 17

middle cerebral artery occlusion

Answer 17

• take out face and hand

- may leave leg area intact (though 2ndry swelling may compromise function)

Question 18

anterior cerebral artery stroke

Answer 18

• supplies medial part of frontal lobes including leg area of motor cortex
• impairment of decision making (Abulia)

Question 19

jacksonian seizure

Answer 19

• partial onset seizure becoming generalised

- associated with motor cortex abnormalities

Question 20

posterior parietal cortex

Answer 20

somatosensory and visual afferents
s30
body or environment image is disrupted- resulting in neglect

Question 21

perceptual motor dysfunction

Answer 21

see s31 diagram

Question 22

premotor area

Answer 22

• important in visually guided movements eg reaching hand to grasp something

Question 23

some stuff about finger activation

Answer 23

simple finger flexion:
- M1 activated

complex finger movement sequence:

• M1 activated
• SMA

mental rehearsal of finger movements
- SMA

Question 24

apraxia

Answer 24

damage to the bit between sensory and motor

apraxia is the inability to carry out purposeful movements, without paralysis

sequence of movements is particularly hard

types of apraxia:

1. ideational (parietal)
   - unable to report sequence
   - ie show me how to make a sandwitch
2. ideomotor (SMA)
   - unable to use the tool
   - cant use pair of scissors

Question 25

task specific dystonias

Answer 25

eg writers cramp

• motor manifestation caused by sensory processing problem
• mediated by basal ganglia

dystonia = sustained muscle contractions

Question 26

basal ganglia

Answer 26

function: positive feedback loop with cortex to select wanted movements and deselect unwanted movements

Question 27

anterior cingulate gyrus function

Answer 27

A component of the limbic system, it is involved in processing emotions and behavior regulation. It also helps to regulate autonomic motor function.