practical 3 motor pathways W3

Question 1

frontal lobe - motor structures?

Answer 1

primary motor cortex (pre-central gyrus)
pre-motor cortex (anterior to primary motor cortex)
Broca’s area (motor control of speech)

Question 2

which hemisphere is Broca’s area predominantly located?

Answer 2

dominant hemisphere (usually left)

Question 3

which region of the primary motor cortex gives rise to the upper motor neurons concerned with cortico-bulbar projections?

Answer 3

inferior lateral

Question 4

which region of the primary motor cortex gives rise to the upper motor neurons concerned with cortico-spinal projections?

Answer 4

superior medial

Question 5

corona radiata?

Answer 5

contains projection fibres passing down from the cortical surface into the internal capsule

Question 6

where in the internal capsule are the corticospinal and corticobulbar fibres located?

Answer 6

posterior limb of the internal capsule

corticospinal: near retrolenticular region

corticobulbar: nearer genu

Question 7

corticospinal pathway?

Answer 7

->primary motor cortex
->corona radiata
->internal capsule
->crus cerebri
->pyramid
->decussation of the pyramid
->lateral corticospinal tract
->ventral horn

Question 8

where are the cell bodies of the upper motor neurons in the corticospinal tract primarily located?

Answer 8

principally in the primary motor cortex

Question 9

where are the cell bodies of lower motor neurons located?

Answer 9

in ventral grey horn of the spinal cord (axons exit spinal cord in ventral root and merge with dorsal root to form a mixed spinal nerve)

Question 10

what happens to the majority of descending cortico-spinal motor axons at the decussation of the pyramids?

Answer 10

the cross to the contralateral side

Question 11

location of crus cerebri?

Answer 11

large ventral/lateral structure in midbrain

Question 12

location of pyramids of the medulla?

Answer 12

medial ventral columns in medulla.

Question 13

how to identify decussation of the pyramids on an isolated brainstem?

Answer 13

area of pyramids where the ventral median fissure is obscured.

on a cross section, large area of crossing fibres between pyramids

Question 14

approximate location of lateral and ventral corticospinal tracts in spinal cord cross sections?

Answer 14

lateral: lateral to dorsal horn
medial: along ventral median fissure

Question 15

main difference between lateral and ventral corticospinal tracts?

Answer 15

lateral: decussated in medulla

ventral: ipsilateral, will decussate in spinal cord close to vertebral level where target lower motor neurons are located

Question 16

do upper motor neurons in the lateral and ventral corticospinal tracts synapse on lower motor neurons in the ipsilateral or contralateral ventral grey horn of the spinal cord?

Answer 16

nearly all synapse on to lower motor neurons on the contralateral side

Question 17

4 important extrapyramidal tracts?

Answer 17

rubrospinal
vestibulospinal
tectospinal
reticulospinal

Question 18

where are the UMN cell bodies of the rubrospinal tract located?

Answer 18

red nucleus

Question 19

where are the UMN cell bodies of the vestibulospinal tract located?

Answer 19

vestibular nuclei

Question 20

where are the UMN cell bodies of the tectospinal tract located?

Answer 20

superior colliculus

Question 21

where are the UMN cell bodies of the reticulospinal tract located?

Answer 21

reticular formation

Question 22

location of the red nucleus?

Answer 22

midbrain
bilateral oval structures deep to substantia nigra and crus cerebri

Question 23

location of the superior colliculus?

Answer 23

midbrain
bilateral oval structures on dorsal side. superior to inferior colliculus. below thalamus.

Question 24

location of the vestibular nuclei?

Answer 24

pons
dorsal

Question 25

where does the vestibulospinal tract receive information from? what does it activate?

Answer 25

receives info from labyrinthine system and cerebellum

activates extensor motor neurons concerned with maintenance of anti-gravity posture

Question 26

where does the rubrospinal tract receive information from? what does it activate?

Answer 26

receives info from cortex and cerebellum

activates motor neurons of flexor muscles

Question 27

where does the reticulospinal tract receive information from? what does it activate?

Answer 27

receives information from the hypothalamus

activates motor neurons concerned with reflex activity, muscle tone, breathing and circulatory system

Question 28

where does the tectospinal tract receive information from? what does it activate?

Answer 28

receives information from visual system

activates motor neurons reflex response to visual stimuli

Question 29

features of the basal ganglia?

Answer 29

sub-cortical nuclei
extensive connections to cortex and thalamus
‘checking system’ for motor activity
facilitate wanted movements
eliminate inappropriate movements

Question 30

major components of the basal ganglia?

Answer 30

caudate nucleus
putamen
globus pallidus
substantial nigra

Question 31

what do the caudate nucleus and putamen form?

Answer 31

neostriatum (striatum)

Question 32

location of the caudate nucleus?

Answer 32

follows curvature of lateral ventricle.

on a horizontal section, the head is found anterior and medial to the anterior limb of the internal capsule

on a coronal section, found between the internal capsule and the corpus callosum

Question 33

location of the putamen?

Answer 33

on a horizontal section, found lateral to globus pallidus

Question 34

location of the globus pallidus?

Answer 34

on a horizontal section, lateral to the internal capsule (internal and external segments)

Question 35

location of the substantia nigra?

Answer 35

ventral midbrain
deep to the crus cerebri

Question 36

principle functional pathways through the basal ganglia?

Answer 36

the direct pathway: promotes movement

the indirect pathway: inhibits movement

Question 37

what neurotransmitter does the substantia nigra use? what is its effect?

Answer 37

dopamine
activates striatum (direct pathway)
inhibits striatum (indirect pathway)

Question 38

have you learnt the diagram yet!! (in notion notes - basal ganglia pathways)

Answer 38

!!!