Cerebellar

Question 1

What fibres make up the three cerebellar peduncles?

Answer 1

Caudal peduncle - afferent fibres from the medulla, the vestibular nuclei via the vestibulocerebellar tracts and the spinal cord via the spinocerebellar tracts
Middle peduncle - afferent fibres to the cerebellum that arise from transverse fibres of the pons
Rostral peduncle - mainly efferent fibres to the mesencephalon, also a few afferent fibres from the spinocerebellar tracts

Question 2

What are the three longitudinal regions?

Answer 2

Medial zone - contains vermis and fastigial nucleus - regulates tone and posture and position of body in general
Intermediate zone - contains interpositus nucleus and cortex adjacent to vermis - adjusts the orientation of the limbs in space, maintaining balance, posture and muscle tone during complex movements
Lateral zones - consisting of the lateral nuclei and lateral portions of the cerebral hemispheres - similar function but do not influence posture or muscle tone directly

Question 3

What are the three layers of the cerebellum and what do they consist of?

Answer 3

Molecular layer - acellular and consists primarily of dendritic zones of the Purkinje cells and axons of granular cells
Purkinje layer (middle) - one cell thick and consists of Purkinje neurons
Granular layer - densely cellular with granular neurons (inner)

Question 4

What are mossy fibres

Answer 4

One of the major afferent nerves which run through the cerebellar peduncles - originate from the brainstem and spinal cord. These send collateral fibres to synapse with cerebellar nuclei and terminate by synapsing with granular neurons on the cerebellar cortex. The fibres are facilitatory at these synapses. The axons that are sent to the molecular layer course transversely through it and synapse with the dendritic zone of multiple Purkinje cells - also facilitatory

Question 5

What are climbing fibres?

Answer 5

One of the major afferent nerves in the peduncles - originate from the olivar y nucleus - these send collaterals to synapse on neurons in the cerebellar nuclei and the axon continues through the cortex to synapse with the dendritic zone of Purkinje neurons in the molecular layer

Question 6

What are the sole efferent fibre of the cerebellar cortex?

Answer 6

Purkinje neurons - majority terminate on neurons in cerebellar nuclei but direct projections to vestibular nuclei occur through caudal cerebellar peduncle.
These are inhibitory and use GABA

Question 7

What ascending white matter tracts are involved in EDM?

Answer 7

Spinocerebellar - unconscious proprioception, hind limbs
Spinocuneocerebellar - unconscious proprioception, forelimbs
Dorsal column medial lemniscal tract - conscious proprioception