9. Cerebellum, Basal Ganglia, Extrapyramidal System Flashcards
What do the extrapyramidal systems control?
Voluntary movement
What does the corticobulbar pathway control?
Muscles in the head and neck
Give the corticobulbar pathway
- Arise from the lateral aspect of the primary motor cortex
- Fibres converge and pass through genu of the internal capsule
- Go through pyramids of the medulla
- Synapse of motor nuclei of cranial nerves
- Lower motor neurons to muscles of head and neck
Which cranial nerves are not innervated bilaterally?
VII below the eyes
XII
Give the corticospinal pathway
- Cortex
- Posterior limb of internal capsule
- 85% decussate in the medulla and enter the lateral corticospinal tract
Terminate in the ventral horn - 15% remain ipsilateral in the anterior corticospinal tract
Decussate and terminate in the ventral horn
What are the symptoms of an upper motor neuron lesion?
Ipsilateral: weakness, hypertonicity, hyperreflexia, clonus, babinski’s sign
What happens in an upper motor neuron lesion to the facial nerve?
Face droops below eye on the contralateral side
What are the symptoms of a lower motor nerve lesion?
Ipsilateral: paralysis, muscle wasting, fasciculations, hypotonicity, hyporeflexia
What happens in a lower motor neuron lesion to the facial nerve?
Facial muscles are damaged above and below eyes
Where is the cerebellum situated in the skull?
Posterior cranial fossa
What membrane surrounds the cerebellum?
Tentorium cerebelli
What does the superior cerebellar peduncle connect the cerebellum to?
Midbrain
What does the middle cerebellar peduncle connect the cerebellum to?
Pons
What does the inferior cerebellar peduncle connect the cerebellum to?
Medulla
What is the name of the midline of the cerebellum?
Vermis
What are the lobes of the cerebellum?
Anterior
Posterior
Flocculonodular
What are the functional divisions of the cerebellum?
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
What does the vestibulocerebellum control?
Balance
What is the main nucleus in the vestibulocerebellum?
Fastigial
What problems are associated with the vestibulocerebellum?
Problems with walking, posture and eye movements
What does the spinocerebellum control?
Muscle tone and posture
What are the main nuclei in the spinocerebellum?
Globose and emboliform
What does the cerebrocerebellum control?
Muscle coordination, planning movement
What is the main nucleus in the cerebrocerebellum?
Dentate
What problems are associated with the cerebrocerebellum?
Intention tremor
Nystagmus
Dysdiadokinesis
Give the cerebrocerebellar pathway?
1. From pre and post central gyrus Frontopontine fibres Pontine nuclei Pontocerebellar fibres Opposite cerebellar hemisphere and nuclei 2. Superior cerebellar peduncles to opposite medulla Ventral lateral nucleus of thalamus Precentral gyrus
What is special about the cerebrocerebellar pathway?
Double decussation causes ipsilateral effects
What pathway is associated with the vestibulocerebellum?
Reticular/vestibular system
What pathway is associated with the spinocerebellum?
Red nucleus
What is contained in the corpus striatum?
Caudate
Putamen
Globus pallidus
What is contained in the neo striatum?
Caudate
Putamen
What is contained in the lentiform nucleus?
Putamen
Globus pallidus
What are the 2 parts of substantia nigra?
Pars compacta
Pars reticulata
What afferents enter the striatum?
Cortex
Thalamus
Pars compacta
What efferents leave the striatum?
Globus pallidus
Pars reticulata
Cortex
Upper motor neurons
What is Parkinson’s caused by?
Loss of dopaminergic neurons in pars compacta
What is Huntington’s caused by?
Loss of neurons in striatum and frontal and parietal cortex
What is hemiballismus caused by?
Lesion in contralateral subthalamic nucleus
