Motor Systems and Associated Structures

Question 1

where is lamina 9 of rexed’s laminae found and what does it contain?

Answer 1

ventral horn of spinal cord
cell bodies of lower motor neuron cell bodies

Question 2

what neuron fibre type carries motor information to skeletal muscle

Answer 2

A alpha

Question 3

are A alpha fibres myelinated

Answer 3

yes

Question 4

what type of muscle fibre supplies muscle spindle

Answer 4

a-gamma

Question 5

what type of neuron fibre is unmyelinated

Answer 5

C

Question 6

how does the size of CNS synapse compare to a neuromuscular junction

Answer 6

neuromuscular junction much larger (up to 50x bigger)

Question 7

what type of neurotransmitter is found in NMJ

Answer 7

acetylcholine

Question 8

how muscle fibres does a NMJ supply

Answer 8

one

Question 9

function of upper motor neurons

Answer 9

control firing pattern of lower motor neurons

Question 10

what is the simplest motor pathway called

Answer 10

corticospinal pathway

Question 11

function of corticospinal pathway

Answer 11

control of voluntary and precise movement

Question 12

how many neurons in corticospinal pathway

Answer 12

2 (upper and lower)

Question 13

is the corticospinal pathway contralateral or ipsilateral

Answer 13

contralateral

Question 14

corticospinal pathway is aka

Answer 14

pyramidal tract/pathway

Question 15

what five locations can upper motor neuron cell bodies be found

Answer 15

primary motor cortex (majority)
pre-motor cortex
supplementary motor cortex
cingulate motor cortex
somatic sensory cortex

Question 16

pathway of an upper motor neuron

Answer 16

1. cortical grey matter (e.g. primary motor cortex)
2. corona radiata
3. internal capsule
4. crus cerebri of midbrain
5. pontine corticospinal tracts
6. pyramid of medulla
7. lateral/ventral corticospinal tracts of spinal cord

Question 17

where is the crus cerebri found

Answer 17

anterior lateral aspects midbrain (R and L)
thick section of white matter (note - may be stained dark)

Question 18

what feature can help identify the pons on a stained cross section

Answer 18

horizontal darker lines

Question 19

where are the pontine corticospinal tracts found

Answer 19

medial and anterior pons

Question 20

where are pyramids of the medulla found

Answer 20

triangular shapes on anterior medial medulla

Question 21

where do neurons decussate in the corticospinal pathway

Answer 21

75-90% in decussation of the pyramids
10-25% in spinal cord at level of lower motor neuron

Question 22

the neurons which decussate in the medulla form which pathway

Answer 22

lateral corticospinal pathway

Question 23

the neurons which do not decussate in the corticospinal pathway form which pathway

Answer 23

ventral corticospinal pathway

Question 24

where does the ventral corticospinal neurons decussate

Answer 24

ventral white commissure

Question 25

an overactive reflex arc leads to

Answer 25

spasticity

Question 26

what pathway controls motor innervation to the cranial nerves

Answer 26

corticobulbar pathway

Question 27

where are the lower motor neurons located that are controlled by the upper motor neurons found in the corticobulbar pathway

Answer 27

cranial nerve nuclei of the brain stem

Question 28

what are the 4 extra-pyramidal motor pathways

Answer 28

rubrospinal tract vestibulospinal tract tectospinal tract reticulospinal tract

Question 29

is the rubrospinal tract contralateral or ipsilateral

Answer 29

contra

Question 30

is the vestibulospinal tract contralateral or ipsilateral

Answer 30

ipsi

Question 31

is the tectospinal tract contralateral or ipsilateral

Answer 31

contra

Question 32

is the reticulospinal tract contralateral or ipsilateral

Answer 32

ipsi

Question 33

where are the cell bodies of the rubrospinal tract found

Answer 33

red nucleus in midbrain

Question 34

where are the cell bodies of the vestibulospinal tract found

Answer 34

vestibular nuclei in pons and medulla

Question 35

where are the cell bodies of the tectospinal tract found

Answer 35

superior colliculus in midbrain

Question 36

where are the cell bodies of the reticulospinal tract found

Answer 36

reticular nuclei in brain stem

Question 37

effects of upper motor neuron loss

Answer 37

voluntary movements of affected muscles are weak no profound muscle atrophy but may be slow wasting spasticity (due to no inhibition to relfex acrs) postitive babinski reflex (dorsiflexion of big toe when stroking sole of foot)

Question 38

effects of lower motor neuron loss

Answer 38

affected muscles are weak or paralysed (if all LMN are lost) profound muscle atrophy tendon reflexes are weak or absent fibrillation potentials can be recorded from denervated muscle fasciculation occurs (irregular muscle twitching)

Question 39

are the basal ganglia pyramidal or extra pyramidal

Answer 39

extra

Question 40

function of basal ganglia

Answer 40

filter out unwanted movement and approve wanted movement

Question 41

diseases caused by basal ganglia loss of function

Answer 41

parkinsons huntingtons

Question 42

what are the six parts of the basal ganglia

Answer 42

caudate putamen globus pallidus external globus pallidus internal subthalamic nucleus substantia nigra

Question 43

the putamen, globus pallidus external and globus pallidus internal form the

Answer 43

lentiform nucleus

Question 44

where is subthalamic nucleus found

Answer 44

superior to hypothalamus which is superior to pituitary

Question 45

where is substantia nigra found

Answer 45

midbrain just posterior to the crus cerebri