cerebellum & basal ganglia

Question 1

describe the structural anatomy of the cerebellum

Answer 1

-located at the back of the brain and sits in the posterior cranial fossa
-has 2 hemispheres that are connected by the vermis
-high folded surface - folds are called folia to increase SA
-divided into the anterior lobe, posterior lobe and the flocconodular lobe

Question 2

what are the 3 lobes of the cerebellum?

Answer 2

-anterior
-posterior
-flocconodular lobe

Question 3

describe the functions of the cerebellum - briefly

Answer 3

• motor coordination - integrates sensory info from body to cooridinate and fine tune movements
  -balance & posture control
  -motor learning & skill acquisition

Question 4

how is the cerebellum separated form the temporal and occipital lobes?

Answer 4

by the tentorium cerebelli

Question 5

describe the grey and white matter of the cerebellum

Answer 5

Grey matter – located on the surface of the cerebellum. It is tightly folded, forming the cerebellar cortex.
White matter – located underneath the cerebellar cortex. Embedded in the white matter are the four cerebellar nuclei

Question 6

what are the functional divisions of the cerebellum?

Answer 6

-vestibulocerebellum - balance and ocular mvts
-spinocerebellum - coordination of body & limbs
-cerebrocerebellum - plan/execute movements

Question 7

what are the 3 zones of the cerebellum?

Answer 7

-lateral hemipsheres
-intermediate zone
-vermis

Question 8

what functional anatomy region would a midline lesion of the cerebellum affect ?

Answer 8

vestibulocerebellum or spinocerbellum

Question 9

what symptoms would be associated with a midline lesion of the cerebellum (vestibulocerebellum or spinocerebellum)?

Answer 9

-loss of balance
-disturbed gait
-nystagmus (uncontrolled eye mvt)

Question 10

what functional anatomy zone would a lateral lesion of the cerebellum affect?

Answer 10

-cerebrocerebellum

Question 11

what symptoms would be associated with a lateral lesion of the cerebellum? (cerebrocerebellum area )

Answer 11

-loss of co-ordination and unsteady gait
-no sensory deficit or muscular weakness

Question 12

what symptoms would be associated with a bilateral dysfunction eg degeneration of the cerebellum?

Answer 12

-lack of coordination
-intention tremor (rhythmic tremor during a direct and purposeful motor movement)
-unsteady gait

Question 13

what are the cerebellar tonsils?

Answer 13

they are triangular structures on the posterior lobe

Question 14

what is an important clinical note about the cerebellar tonsils?

Answer 14

if the intracranial pressure is raised eg during haemorrhage for if there is malformation (congenital) - the cerebellar tonsils can be herniated through the foramen magnum

Question 15

what 3 paired arteries provide blood supply to the cerebellum?

Answer 15

-Superior cerebellar artery (SCA)
-Anterior inferior cerebellar artery (AICA)
-Posterior inferior cerebellar artery (PICA)

Question 16

what artery are the superior cerebellar artery (SCA) and the anterior inferior cerebellar artery (AICA) branches of?

Answer 16

the basilar artery

Question 17

what artery is the posterior inferior cerebellar artery a branch of?

Answer 17

the vertebral artery

Question 18

what 2 main veins is drainage of the cerebellum done by?

Answer 18

superior and inferior cerebellar veins.

Question 19

what are the basal ganglia?

Answer 19

a group of subcortical nuclei responsible primarily for motor control, as well as other roles such as motor learning, executive functions and behaviours, pain processing etc

Question 20

what important neurotransmitter do the BG require to function?

Answer 20

dopamine

Question 21

what are the input nuclei of the basal ganglia?

Answer 21

-caudate
-putamen
-accumbens

Question 22

what are the output nuclei of the basal ganglia?

Answer 22

-globus pallidus internal
-substantia nigra pars reticulata

Question 23

what are the intrinsic nuclei of the basal ganglia?

Answer 23

-External globus pallidus
-Subthalamic nucleus
- Pars compacta of the substantia nigra

Question 24

what is the function of the basal ganglia?

Answer 24

-motor control - contribute to the initiation, execution and regulation of voluntary mvts - work with cerebral cortex & cerebellum,
-procedural learning - acquiring skills & habits through practice & repetition
-inhibition of unwanted movements

Question 25

describe the vasculature of the basal ganglia

Answer 25

-comes mainly from the middle cerebral artery (a continuation of the internal carotid artery)
-lenticulostriate arteries - providing vascular supply to the lenticular nucleus and the striatum

Question 26

what is the striatum?

Answer 26

used to refer collectively to the caudate nucleus, putamen and nucleus accumbens

Question 27

what are examples of basal ganglia pathologies?

Answer 27

-stroke
-parkinsons disease
-huntingtons disease
-tourette syndrome
-OCD

Question 28

briefly describe the ‘motor pathways’ to coordinate and control movements in the basal ganglia

Answer 28

-when you want to make a voluntary mvt, the motor cortex sends a signal to the BG
-the BG sends a signal to the thalamus which acts as a relay station
-thalamus sends signal back to the motor cortex which fine tunes the movement instructions
-then motor cortex sends signal to muscles to carry out the movement

Question 29

what is an example of a hypo kinetic syndrome?

Answer 29

parkinsons disease

Question 30

what are the clinical features of Parkinsons disease?

Answer 30

-tremors
-bradykinesia -slowness of movement
-rigidity - muscle stiffness or rigidity
-impaired balance and coordination

Question 31

what systems of the brain does parkinsons disease affect?

Answer 31

-loss of dopaminergic neurons in the substantial nigra pars compact and reduction of levels of dopamine in the striatum

Question 32

what is Huntington’s disease?

Answer 32

-progressive and inherited neurological disorder that affects movement, cognition, and behavior
-caused by mutation in the HTT gene

Question 33

what us an example of a hyperkinetic disease & why?

Answer 33

-Huntington’s disease
-this disease is caused by a mutation in the HTT gene and is characterised by involuntary jerky and rapid movements

Question 34

what structures are impaired in parkinsons disease?

Answer 34

parkinsons is characterised by the degeneration of the dopaminergic neurons in the substantia nigra pars compacta
-this leads to disruptive signalling to the striatum from this structure and leads to bradykinesia etc

Question 35

describe the structure of the internal capsule as seen on a horizontal section of the hemisphere

Answer 35

• in a horizontal section, the internal capsule is seen as a white matter structure located deep within the brain, separating the basal ganglia and thalamus from the cerebral cortex
  -consists of 3 parts - the anterior limb, the genu & the posterior limb

Question 36

outline the anatomical relations of the internal capsule and the distribution of the motor fibres in relation to the different positions of it

Answer 36

-serves as a major pathway for transmitting sensory and motor information between the cerebral cortex and the brainstem or spinal cord
-anterior limb - fibres are located more medially and include the corticopontine fibres
-genu -corticobulbar motor fibres pass through
-posterior limb -motor fibres are positioned more laterally - the corticospinal tract

Question 37

briefly describe the motor deficit arising from a stroke in the internal capsule

Answer 37

• it would cause contralateral weakness in muscles
• damage to the motor pathways can result in increased muscle tone & spasticity (ie involuntary contractions)
• loss of motor co-ordination