Week 1 - D - Neuroanatomy 3 - Basal ganglia and cerebellum

Question 1

The three oval objects all have arrows that come from the same structure, it just changes position as we ascend through the brainstem What is this structure? What is the arrow going to in the midbrain?

Answer 1

This is the medial lemniscus The arrow going to the midbrain shows the cerebral aqueduct

Question 2

What sensation does the dorsal column / medial lemniscus tract provide? What sensation does the spinothalamic tract provide? (which ones are by the lateral and which by the anterior spinothalamic tracts) What tract provides fine precise movement and supplies axial and limb muscles?

Answer 2

DCML - fine touch, vibration and proprioception Spinothalamic - deep pressure, temperature and pain Deep pressure - anterior Temperature/pain - Lateral Corticospinal tract is the desceding pathway supplying these movements

Question 3

What would an infarct in the intenal capsule result in for the corticsopinal tract? Internal capsule is where the axons travel in the cerebral hemispheres

Answer 3

This would result in spastic paralysis with hyperflexion of the limbs

Question 4

Lateral hemisection of the spinal cord is also known as Brown-Sequard syndrome Explain the features of Brown-Sequard syndrome? ie if there was a right hemisection of the spinal cord

Answer 4

There would be ipsilateral loss of fine touch, vibration and proprioception sensation - DCML There would be contralateral loss of deep pressure, temperature and pain - Spinothalamic tract There would be ipsilateral paralysis and ipsilateral hyperfelxia

Question 5

Generally the frontal cortex is very much involved in motor control very much further then just the precentral gyrus if there is an intended movement planned in the precentral gyrus (primary motor cortex), what 2 parts of the brain and what tract carries out the action?

Answer 5

The basal ganglia and the cerebellum are informed of the action The corticospinal tract delivers the information to the muscles to carry out the action

Question 6

When the sensory fibres return with information regarding the movement, where do these fibres return the information before it reaches the thalmus?

Answer 6

The sensory information regarding the movement is returned to the cerebellum before the thalamus

Question 7

The cerebellum is largely a movement computer – also has functions of motor memory What two functions does the cerebellum mainly control?

Answer 7

Mainly controls movement and coordination

Question 8

What are the three lobes of the cerebellum?

Answer 8

The anterior lobe, posterior lobe and flocculonodular lobe

Question 9

Where is the flocculus of the flocculonodular lobe located?

Answer 9

It is located at the ponto-medullary junction of the brainstem The 2 floccus is on the outer parts and the nodulus is in the centre of the lobe

Question 10

Why is the cerebellum described as subtentorial?

Answer 10

This is because it lies beneath the tentorium cerebelli

Question 11

The cerebellum like the crerbral hemispheres has a core of white matter with a outside grey matter (there are some grey matter structure deep in the cerebellum however) At what level of the brainstem is the white matter entering the cerebellum? what sits between this level and the cerebellum?

Answer 11

Enters at the level of the pons Will find the fourth ventricle and between the cerebellum and the pons here

Question 12

the cerebellum is attached to the brainstem via three peduncles What are these peduncles known as? Which is by far the biggest?

Answer 12

Known as the superior cerebellar peduncle, the middle cerebellar peduncle and inferior cerebellar peduncle The middle cerebellar peduncle is by far the biggest

Question 13

Which lobe lies anterior to the primary fissure of the cerebellum and which lies posterior to it?

Answer 13

The anterior lobe lies anterior to primary fissure Posterior lobe lies posteriorly

Question 14

If we took the cerebellum, cut it off at the three peduncles and flattened it What would the area of gyri that is pinched together be known as? What fissure exists between the flocculonodular lobe and the posterior lobe?

Answer 14

This area would be known as the vermis The posterolateral fissure exists between the flocculonodular and posterior lobes

Question 15

What is the cerbellar white matter known as? (tree of life)

Answer 15

It is known as the arbor vitae

Question 16

If we slice of the top of the cerebellum we are able to locate the deep grey matter structures of the cerebellum How many deep grey matter structures are there on each side of the cerebellum? What is the largeest deep grey matter structure known as?

Answer 16

There are 4 deep grey matter structures on each side of the cerebellum with the largest known as the dentate nucleus

Question 17

The cerebellar cortex is divided into 3 layers What are these three layers?

Answer 17

These are the Molecular layer Purkinje layer Granular layer

Question 18

Important afferents arrive to the cerebellum via cerebellar peduncles and project mainly to which layer of the cerebral cortex?

Answer 18

They project mainly to the granular layer of the cerebral cortex

Question 19

From all three lobes of the cerebellum: the only output is via the axons of which cells? Where do the axons of these cells synapse?

Answer 19

The only output is via the purkinje cells of the cerebral cortex and their axons synapse on the deep cerebellar nuclei

Question 20

Most efferent axons of deep cerebellar nuclei cross the midline Where do the axons then synapse before travelling to the motor cortex?

Answer 20

The axons synapse in the thalamus before travelling to the primary motor cortex

Question 21

The cerebellum has functional divisions as it is split into hemispheres Do cerebellar hemispheres influence the ipsi or contralateral side of the body? Also - posterior fissure is meant to be posterolateral in pic

Answer 21

Cerebellar hemispheres influence the ipsilateral side of the body

Question 22

If there is a lesion in the cerebellar hemispheres, ipsilateral signs and symptoms will occur Will the symptoms be motor or sesnory? Which layer of the cerebellar cortex is mainly for afferent information? What is the only efferent output of the cerebellum?

Answer 22

The symptoms will be a mixture of motor and sensory as the cerebral hemispheres contain information for both Afferent informaton = granular cells Efferent information = purkinje cells (their axons synapse on the deep cerebellar nuclei which then synapse in the thalamus before travelling to the primary motor cortex)

Question 23

The divisions of the cerebellum have different functions If there is a lesion in the folliculonodular lobe, what effects will occur? (clue folliculonodular lobe is closely linked to the vestibular nuclei)

Answer 23

Can result in visual disturbances such as vertigo and nystagmus

Question 24

What can unilateral hemispheric lesions result in? (the hemispheres are involved in planning movement that is about to occur)

Answer 24

This can result in disturbance of coordination ie unsteady gait in absence of weakness

Question 25

Lesions in the midline of the cerbellum can result in what defecit?

Answer 25

Can result in loss of postural control ie falling when standing or sitting

Question 26

Bilateral cerebellar dysfunction results in what symptoms?(Acute alcohol exposure typically results in bilateral cerebellar hemisphere dysfunction and presents with cerebellar ataxia. - think of symptoms when drunk)

Answer 26

Bilateral cerebellar dysfunction can result in slowed speech and incoordinated gait / wide based gait (cerebellar ataxia)

Question 27

Run through again symptoms of lesions in cerebellum Unilateral hemispheric lesion? Bilateral cerebellic dysfunction? Midline lesion? (think posture becuase stand straight (midline) Lesion in the flocculonodular lobe? What cells relay afferent info and which relay efferent info to the deep cerebellar nuclei? What is the biggest of the 4 deep cerebellar nuclei?

Answer 27

Unilateral hemispheric lesion - causes loss of coordination - ie unsteady gait Bilateral cerebllic dysfunction - results in slowed speech, wide based gait Midline lesion - results in disturbance of postural control Flocculonodular - vestibular distrubances (eg nystagmus/vertgo) Granular cells - afferent fibres Purkinje cells - efferent Dentate nuclei is the largest

Question 28

What are the functions of the basal ganglia?

Answer 28

To facilitate purposeful movement To inhibit unwanted movement Role in posture and muscle tone

Question 29

Basal Ganglia A number of masses of grey matter located near the base of each cerebral hemisphere What are the 5 structures that contribute to the basal ganglia?

Answer 29

Caudate nucleus Putamen Globus pallidus Subthamic nucleus Substania nigra

Question 30

The 5 parts of the basal ganglia can be separated into different parts Example - what is the putamen + globus pallidus collectively known as?

Answer 30

This is known as the lentiform nucleus - shape of a lentil

Question 31

What is the putamen + globus pallidus + caudate nucleus known as? And what is just the caudate nucleus + putamen known as?

Answer 31

putamen + globus pallidus + caudate nucleus = collectively known as the Corpus striatum Caudate nucleus + putamen - Striatum

Question 32

The globus pallidus occurs in two stripes – lateral and medial Is the globus pallidus or putamen closer to the thalamus?

Answer 32

The globus pallidus is found closer to the thalmus

Question 33

What separates the globus pallidus and the thalamus? Where is the body of the caudate nucleus found in relation to the lentiform nucleus?

Answer 33

They are separated by the internal capsule (the huge strip of white matter It is found superomedially

Question 34

The basal ganglia is found relatively near the base of cerebral hemispheres Can see on axial slice What structure of the basal ganglia will you be able to see if looking at the lateral wall of the lateral ventricle?

Answer 34

Will be able to see the caudate nucleus as it follows the same pathway as the lateral ventricle

Question 35

Where is the substantia nigra found and what colour is it? What chronic disease is it lost in?

Answer 35

Substantia nigra is found in the midbrain and is black It is lost in Parkinson's disease

Question 36

What are the type of neurones that degenerate in parkinsons disease hence the treatment? What is a drug used to treat parkinosons?

Answer 36

It is the dopaminergic neurones of the substantia nigra that degenerate Levodopa is a dopamine agonst used to treat parkinsons

Question 37

What are the two pathways of the basal ganglia and what are the wanted outcomes?

Answer 37

The direct pathway - enhances outflow of thalamus, enhancing desired movement The indirect pathway - inhibits outflow from thalamus

Question 38

Label the arrows from top to bottom

Answer 38

Caudate nucleus Thalamus Putamen Lateral globus pallidus Medial globus pallidus Subthalamc nucleus Substantia nigra

Question 39

Lesiosn in the basal ganglia in contrast to lesions in the cerebellum affect which side of the body?

Answer 39

Lesions in the basal ganglia affect the contralateral side of the body in contrast to lesions in the cerebellum

Question 40

Lesions of the basal ganglia generally do not cause paralysis, sensory loss, loss of power, or ataxia. If there is a tremor, do you think basal ganglia or the cerebellum shoudl be affected? Give example of the disease affected by degeneration of the dopaminergic neurones in the substantia nigra which presents with tremors

Answer 40

The basal ganglia Parkinsons is a good example

Question 41

What kind of signs do lesions in the basal ganglia cause? (usually affect control of muscles)

Answer 41

Cause symptoms like brady/dsykineasia Changes in muscle tone Tremor Myoclonal jerk Chorea - dancing muscles - huntingsons

Question 42

Pathology: degeneration of dopaminergic neurons of the substantia nigra What is this? what are its three main features?

Answer 42

Parkinson's disease involuntary shaking of particular parts of the body (tremor) slow movement stiff and inflexible muscles

Question 43

What is impairment of power of voluntary movement known as?

Answer 43

Akinesia

Question 44

Genetics: autosomal dominant disorder Pathology: progressive degeneration of the basal ganglia and cerebral cortex Signs: chorea and progressive dementia What is this and what is chorea? What specific area of the basal ganglia is affected in this disease?

Answer 44

This is Huntingson's disease Chorea means dancing (aka limbs move uncontrollably) it is the striatum (caudate nucleus and putamen) that is specifcally initially affected in Huntington's disease

Question 45

What are the five strucutres that make up the basal ganglia? What makes up the lentiform nucleus, striatum and corpus striatum?

Answer 45

Caudate nucleus Putamen Globus pallidus Subthalamic nucleus Substantia nigra Caudate nucleus + Putamen = Striatum Caudate nucleus + Putamen + Globus Pallidus = Corpus striatum Putamen + Globus Pallidus = Lentiform nucleus

Question 46

Activity in the basal ganglia doesnt bring about movememnt itself, it causes activity elsewhere in the brain that then brings about movement What shape does the caudate nucleus follow?

Answer 46

It follows the shape of the lateral ventricle

Question 47

Label all the different colour of circle

Answer 47

Purple - head of caudate nucleus Black - body of caudate nucleus green - thalamus Blue - tail of caudate nucleus Pink - amygdala Silver - golubus pallidus Orange - putamen

Question 48

Label the diagram

Answer 48

Black - the lateral ventricle Silver - caudate nucleus Brown - internal capsule Red - putamen Yellow - medial and lateral globus pallidus Blue - thalamus Purple - insular lobe

Question 49

What functions does the cerebellum act to achieve? What do lesions in each part cause - midline(vermis)?, flocculonodular lobe?, unilateral hemisphere? bilateral cerebellic dysfunction?

Answer 49

Acts to mainly control movement and coordination Midline (vermis) - Dysfunction in postural control (falling when standing/sitting) Flocculonodular - vestibular dysfunction Unilateral hemisphere - loss of coordination - ie unsteady gait Bilateral dysfunction- same symptoms as being drunk - slow slurred speech, wide based gait (cerebellar ataxia) Ataxia is a term for a group of disorders that affect co-ordination, balance and speech

Question 50

What is the main functions of the basal ganglia? Do lesions in the basal ganglia and cerebellum affect the ipsilateral or contralteral side?

Answer 50

Main fucntions - inhibit unwanted movement actions, enhance purposeful movement Role in posture and muscle tone Lesions in basal ganglia affect the contralteral side Lesions in cerebellum affect the ipsilateral side

Question 51

What are the main symptoms of parkinsons and chorea?

Answer 51

Parkinosns Tremor (involuntary muscle movements) Slow movement Stiff and inflexible muscles Also get anosmia in parkinsons (loss of smell) Huntingsons - Chorea and progressive dementia