Neuroanatomy 3

Question 1

what is the internal capsule?

Answer 1

white matter area
visual, motor and many other modalities of information pass through here, therefore a stroke here can be very serious - can cause a lack of descending control of the corticospinal tract causing a spastic paralysis with hyperflexion of the upper limbs (decorticate posturing)

Question 2

a lesion at the level of the midbrain causes what symptoms?

Answer 2

causes lack of descending cortical control of vestibulospinal tract
this leads to domination of extensor muscles and hyperextended spastic paralysis

Question 3

brown sequard’s syndrome?

Answer 3

caused by lateral hemisection of the spinal cord

e. g lesion on right side of spinal cord
- ipsilateral paralysis as motor nerves (corticospinal tract) have already crossed over in the medulla on the way down from the brain so will be on the ipsilateral side to the muscles controlled and will be affected by the injury
- ipsilateral loss of vibratory sense and proprioception as medial lemniscus pathway doesn’t cross over until the medulla on the way up
- contralateral loss of pain and temp sensation as spinothalamic tract crosses over at the level of entry to the spinal cord

Question 4

what other things feed into the primary motor cortex to determine type, strength of movement/contraction etc?

Answer 4

cingulate motor area
supplementary motor area
premotor area
(all can also directly project directly to the spinal cord)

Question 5

function of basal ganglia and cerebellum in movement?

Answer 5

cerebellum receives input from sensory fibres as you are moving and relays this through the thalamus to the motor cortex to plan and execute movement
basal ganglia also feed information through thalamus to improve movement
(knows how you are moving so can coordinate how movement continues through the thalamus, then to the cortex)

Question 6

lobes of the cerebellum

Answer 6

anterior
posterior (biggest)
flocculonodular lobe (like little ears at the base)

Question 7

where does the cerebellum sit?

Answer 7

beneath tentorium cerebellae in the posterior cranial fossa

falx cerebelli sits behind

Question 8

how does cerebellum attach to brainstem?

Answer 8

3 peduncles (stumps) of white matter

• superior, middle (biggest) and inferior
• all carry white matter fibres into the cerebellum

Question 9

vermis of the cerebellum?

Answer 9

worm like middle area of cerebellum

Question 10

what are gyri known as in the cerebellum?

Answer 10

folia

Question 11

where is grey matter found in the cerebellum?

Answer 11

surrounding the thick white matter core (arbour vitae)
some deep grey matter areas within the white matter core (4 areas with different functions and communicate to brainstem etc)

Question 12

layers of cerebellum tissue?

Answer 12

molecular layer (synaptic layer)
purkinjie cell layer (project down to the deeper nuclei which communicate with the brainstem
granular layer (filled with neurons)

Question 13

how does information arrive at the cerebellum?

Answer 13

afferents arrive from:
- spinal cord
- cerebral cortex (relayed via the pons)
- vestibular apparatus via vestibular nuclei
enter via cerebellar peduncles and project into granule cell layer (mainly)

Question 14

outputs from the cerebellum?

Answer 14

central stripe (veremis) involved in subconscious motor function
flocularnodular lobe = receives vestibular information and feeds back to brainstem
only output from all lobes is via axons of purkinjie cells which synapse on neurons of deep cerebellar nuclei, then to the thalamus which then coordinates functions of all motor tracts

Question 15

how is the cerebellum different from the cerebrum?

Answer 15

cerebellar hemispheres are ipsilateral, not contralateral like the cerebrum
- right hemisperes coordinates movement in right side of body etc

Question 16

functional divisions of the cerebellum?

Answer 16

vestibulocerebellum - receives vestibular input and coordinates balance and eye movement
spinocerebellum - receives proprioception information to coordinate limb movement
pontocerebellum - evaluates sensory information and plans for movement

Question 17

midline cerebellum lesion?

Answer 17

disturbance of postural control

patient will fall over when standing or sitting but with preserved limb coordination

Question 18

unilateral hemispheric lesion?

Answer 18

disturbance of coordination in limbs (can cause tremor, unsteady gait etc)

Question 19

bilateral cerebellar lesion?

Answer 19

slowed, slurred speech, bilateral incoordination of the arms and staggering wide based gait(cerebellar ataxia)

Question 20

alcohol and cerebellum?

Answer 20

alcohol temporarily causes bilateral cerebellar hemisphere dysfunction causing cerebellar ataxia

Question 21

what do basal ganglia do generally?

Answer 21

feed back to the cortex 
- facilitate purposeful movement
- inhibit unwanted movements
- role in posture and muscle tone
(should really be called nucleus as ganglia means collection of neurons outside of CNS)

Question 22

what is the basal ganglia?

Answer 22

5 structures aggregated together to perform this function

• caudate nucleus
• putamen
• globus pallidus
• subthalmic nucleus
• substantia nigra

Question 23

striatum?

Answer 23

caudate nucleus and putamen

Question 24

lenticular nucleus?

Answer 24

pitamen and globus pallidus

Question 25

corpus striatum?

Answer 25

caudate nucleus
putamen
globus pallidus

Question 26

where is the caudate nucleus?

Answer 26

round grey matter blob under lateral ventricles

Question 27

where is the putamen?

Answer 27

cone shaped grey matter under caudate nucleus

Question 28

where is the globus pallidus?

Answer 28

2 striped medial to the putamen

much paler

Question 29

where is the substantia nigra?

Answer 29

black line either side within the midbrain

Question 30

how is substantia nigra involved in parkinsons?

Answer 30

substantia nigra produces dopamine

degenerates in parkinsons

Question 31

what is the direct pathway?

Answer 31

series of neurones which travel through basal ganglia to enhance outflow of thalamus to enhance desired movement

Question 32

indirect pathway?

Answer 32

inhibits outflow from thalamus to inhibit unwanted movement

Question 33

what effects result from a lesion in the basal ganglia?

Answer 33

unilateral lesions affect contralateral side of body
do not cause paralysis, sensory loss, loss of power or ataxia
do cause
- changes in muscle tone
- dyskinesias (involuntary movement - tremor, chorea, myoclonus)

Question 34

name 2 diseases associated with basal ganglia

Answer 34

parkinsons

huntingtons