Anatomy of Basal Ganglia and Cerebellum Flashcards
Name the 3 lobes of the cerebellum.
Anterior
Fiocculus
Posterior
What lobe of the cerebellum is smallest?
Fiocculus
What lobe is the flocculus part of?
Fiocculnodular lobe
Where is the primary fissure located?
Just posterior to the anterior lobe
In what lobe would you find the horizontal fissure?
Posterior lobe
The cerebellum is contained within the anterior cranial fossa
FALSE
Posterior
What structure acts like a ‘tent’ over the cerebellum?
Tentorium cerebelli
Describe the positions of white and grey matter in the cerebellum
GREY - OUTSIDE
WHITE - INSIDE
Grey - found deep in the centre of white matter
How is the cerebellum attached to the brain stem?
Via 3 stalks known as peduncles
What are peduncles composed of?
White matter
Name the 3 peduncles.
Superior, middle and inferior
Which of the 3 peduncles is the largest?
Middle
The posterior lobe of the cerebellum is much larger than the anterior lobe
TRUE
The cerebellar cortex has 3 layers. Name these layers in order of superficial to deep.
Molecular layer
Purkinje cell layer
Granule cell layer
What is the purkinje cell layer rich in?
Neurons
Where do afferent nerve impulses to the cerebellum usually come from?
Spinal cord
Cerebral cortex (via pons)
Vestibular apparatus
How do afferent nerve impulses reach the cerebellum?
Via the peduncles
Once afferent impulses reach the cerebellum, where do they go?
Usually granule cell layer
From any lobe of the cerebellum, output can only be via which cell layer?
Purkinje cells
Where do the purkinje cells synapse? What does this control?
On neurones of the deep cerebellar nuclei
The functions all of the motor tracts of the brainstem and spinal cord
Describe the route of most neurones of the deep cerebellar nuclei.
Cross the midline and synapse in the thalamus
The thalamus then sends signals to the motor cortex
Cerebellar hemispheres influence the ipsilateral/contralateral side of the body
IPSILATERAL
Describe the outcome of a unilateral hemispheric lesion.
Disturbance of co-ordination of limbs
Tremor
Unsteady gait
Absence of weakness or sensory loss
Describe the outcome of a bilateral hemispheric lesion.
Slowed, slurred speech
Bilateral incoordination of the arms
Staggering, wide based gait (cerebellar ataxia)
Describe the outcome of a midline hemispheric lesion.
Disturbance of postural control
Patients will fall over when standing or sitting
Outline the 3 functions of the basal ganglia.
Enhance movement
Inhibit unwanted movement
Role in posture and muscle tone
What are basal ganglia?
A number of masses of grey matter located near the base of each cerebellar hemisphere
What is Parkinson’s disease? What are the signs?
Degeneration of dopaminergic neurones of the substantial nigra (dampened output to cortex)
Akinesia, rigidity, resting tremor
Describe the direct pathway of basal ganglia.
Enhances outflow of thalamus and enhances desired movement
Describe the indirect pathway of basal ganglia.
Inhibits outflow of the thalamus
Unilateral lesions of the basal ganglia affect the ipsilateral/contralateral side of the body
CONTRALATERAL
What do lesions of the basal ganglia cause?
Changes of muscle tone
Dyskinesias
Myoclonus
Muscle jerks
Tremor
Sinusoidal movements
Chorea
Rapid, asymmetrical movements
What is Huntington’s disease? What are the signs?
Autosomal dominant disorder of the INDIRECT pathway
Progressive degeneration of the basal ganglia and cerebral cortex
Chorea, progressive dementia
What is dyskinesia?
Abnormality or impairment of voluntary movement
