Term
| What are the primary functions of the Cerebellum? |
|
Definition
1) Compare ongoing movements with intended movements
2) Temporal coordination of movements, stopping movements and initiating movements.
3) Cognitive functions |
|
|
Term
| What is the basic organization of the Cerebellum? |
|
Definition
1) Anterior lobe (separated from posterior by "primary fissure")
2) Posterior lobe
** Anterior and Posterior lobes broken into Vermis, Intermediate Zone (together receiving SC inputs and making the Spinocerebellum) and Lateral Zone (receiving motor cortex inputs and making the Cerebrocerebellum)**
3) Flocculonodular lobe, or "vestibulocerebellum" (underside connected to main cerebellum by spherical nodulus) |
|
|
Term
| Explain the distribution of input types to different regions of the Cerebellum. |
|
Definition
1) Vermis and Intermediate Zone of Anterior Zone + Posterior Zone= Spinocerebellum (SC inputs)
2) Vermis and Intermediate Zone of Lateral Zone= Cerebrocerebellum (Motor inputs)
3) Flocculonodular Lobe= Vestibulocerebellum (Vestibular inputs) |
|
|
Term
| What is the structure of a basic Cerebellar Circuit? |
|
Definition
1) Afferants to cerebellum excite cells in deep cerebellar nuclei (final output).
2) Afferants directly (Climbing fibers) activate Purkinje fibers coming from Superior Peduncl, which inhibit Deep nuclear neurons.
3) Afferents indirectly activate (Mossy fibers) inhibitory neurons in the cerebral cortex, which act on
**Purkinje fibers (regulated by cortical cells) inhibit deep cerebellar nucleus neurons with GABA |
|
|
Term
| What are the major deep cerebellar nuclei and their primary inputs? |
|
Definition
1) Fastigial (medial) gets Purkinje cell inputs from Vermis
2) Globose and Emboliform (together forming "Nucleus interpositus") nuclei can Purkinje inputs from intermediate zone (anterior and posterior lobes)
3) Dentate (most lateral) receives Purkinje inputs from lateral cerebellar cortex.
4) Floculonodular lobe does not have deep nucleus to which it projects, but instead projects to Vestibular nuclei to modify Vestibular neurons. |
|
|
Term
| What inputs does the Cerebellum process? |
|
Definition
1) Climbing Fibers coming from inferior olivary nucleus in caudal medulla (excite Purkinje cells which regulate deep nuclei)
2) Mossy Fibers are all others (mainly influencing interneurons in cerebellar cortex which modulate Purkinje fibers) |
|
|
Term
| How are sensory inputs conveyed to the Cerebellar cortex? What about outputs? |
|
Definition
1) Most via the inferior cerebellar peduncle
- Spinocerebellar tract
- Vestibular (Purkinje fibers from flocculonodular lobe)
- Climbing fibers from inferior olivary nucleus
- Fastigial nucleus neurons influencing reticulospinal and vestibulospinal pathways.
** Efferents from flocculonodular lobe and nucleus to vestibular nuclei and RF**
2) Middle cerebellar peduncle
- Inputs from Pontine nuclei, which receive inputs from Cerebral Cortex
3) Superior Cerebellar Peduncle
- Carries ascending projections to thalamus and the to cortex (major output except for vestibular nuclei and RF that go through inferior peduncle) |
|
|
Term
| Where do each of the deep nuclei project fibers to? |
|
Definition
1) Vestibulocerebellum projects to vestibular nuclei (balance and VOR)
2) Fastigial effects brainstem motor systems that control proximal body movements (reticulospinal and vestibulospinal tracts)
3) Interpositus nuclei effect Corticospinal influence on distal limb muscles
4) Dentate effects premotor and motor regions of cortex. |
|
|
Term
| Explain the Laterality of Cerebellar Inputs and Outputs. |
|
Definition
1) Right cerebellum gets left cerebral cortex, which controls right side of body (ipsilateral defects)
2) Left cortex also goes through Pontine Nuclei, entering at Middle Peduncle
2) Inferior Olivary Nucleus projects climbing fibers contralaterallly via Inferior Peduncle (contralateral defects) |
|
|
Term
| What is the blood supply of the Cerebellum? |
|
Definition
1) PICA is for inferior cerebellum
2) AICA for strip of ventral cerebellum including flocculus
3) SCA is for superior cerebellum including deep nuclei. |
|
|
Term
A patient recently went to get fitted for a new pair of glasses, but they are making him extremely dizzy.
He sways from side-to-side when standing and exhibits a staggering wide-based gait.
What is going on? |
|
Definition
Truncal Ataxia resulting from Flocculonodular lesions or infarction of AICA (flocculus blood supply)
He is getting dizzy from the new classes, because
quick adaptation" involving gain adjustment of the VOR cannot be adjusted without the normal Purkinje projections from the floculunodular lobe to vestibular nuclei.
**Watch out if vestibular system is damaged, because the flocculododular lobe projections won't be able to compensate for developing Nystagmus!** |
|
|
Term
| What conditions can cause Truncal Ataxia? |
|
Definition
1) Floculonodular node lesion/AICA infarction
2) Midline cerebellum damage (vermis and fastigial deep nuclei) because of descending motor pathways (reticulospinal and vestibulospinal) |
|
|
Term
A patient is having difficulty coordinating his distal limbs (i.e he fails the finger-nose-fingure coordination test).
What is going on? |
|
Definition
Appendicular ataxia because of damage to intermediate zone or its projections to the Nucleus interpositus.
Often occurs along with Truncal ataxia, since it is rare for a single area of the Cerebellum to be damaged. |
|
|
Term
| What can you learn from an abnormal Romberg test vs. an abnormal finger-nose-finger test? |
|
Definition
1) Romberg suggests Truncal Ataxia, which could be due to issues with Floculonodular lobe or Vermis/Fastigial Nucleus.
2) Finger-nose-Finger suggests issue with Intermediate zone/Interpositus nucleus. |
|
|
Term
| What are the 6 major clinical manifestations of damage to the Lateral Cerebellar hemispheres/Dentate nucleus? |
|
Definition
3D2H1I
1) Dysmetria (judging distance)
2) Dysdiadochokinesia (rapid alternating movements)
3) Intention tremor
4) Dyssynergia (isolated parts rather then smooth movement)
5) Hypotonia (ipsilateral to lesion)
6) Hyporeflexia (ipsilateral to lesion) |
|
|
Term
| What deep nucleus is associated with each area of the major Cerebellum? |
|
Definition
Remember, major cerebellum is anterior and posterior lobes.
1) Vermis is associated with Fastigial nucleus (reticulospinal and vestibulospinal tracts)
2) Intermediate zone is associated with Interpositus (Emboliform + Globose) (Spinocerebellum)
3) Lateral Zone is associated with Dentate nucleus (Cerebrocerebellum)
4) Floculonodular Lobe is associated with Vestibular nuclei |
|
|
