2.5

Question 1

Function of the cerebellum

Answer 1

Coordinate movement
Maintain posture, balance, and muscle tone
Learning of motor tasks
Process memory of skilled motor activity

Question 2

Morphology of the cerebellum

Answer 2

2 hemispheres
Vermis
Sulci
Peduncles
Horizontal fissure
Arbor vitae

Question 3

Grey matter of the cerebellum

Answer 3

1. Cerebellar cortex: just like that of the cerebellar cortex; an outer layer of grey matter
2. Deep cerebellar nuclei: collections of grey matter embedded in the white matter of the cerebellum

Question 4

Layers of grey matter

Answer 4

Three layers contain more neurons than the cerebral cortex

Question 5

Purkinje cells

Answer 5

Form the middle layer of the cerebellar cortex
Terminate on 2 nuclei:
- deep cerebellar nuclei
- vestibular nuclei (balance)

Question 6

White matter of the cerebellum

Answer 6

Contains:
- afferent (sensory) and efferent (motor) fibers
- association fibers: local fibers which arise from cerebellar Purkinje cells and project to other areas of the cerebellum

Question 7

Where do cerebellar nuclei receive afferents from?

Answer 7

Fastigial nucleus
- vestibular system
Interposed nuclei
- spinal cord
Dentate nucleus
- cerebrum and pons

Question 8

Cerebellar lobes and their connections

Answer 8

Flocculonodular - vestibular system
Anterior - spinal cord
Posterior - cerebral cortex

Question 9

Superior cerebellar peduncle

Answer 9

Principally carries cerebellar signals to midbrain and thalamus
Pathway: efferent from cerebellar cortex and deep nuclei

Question 10

Middle cerebellar peduncle

Answer 10

Carries signals from pons to the cerebellum
Pathway: afferent transverse fibers of the pons

Question 11

Inferior cerebellar peduncle

Answer 11

Connects the cerebellum with the medulla oblongata and spinal cord
Pathway: afferent from spinal cord and brainstem nuclei

Question 12

Communication of the cerebellum

Answer 12

Afferents, efferents, and intrinsic fibers

Question 13

Afferents of the cerebellum

Answer 13

Afferents come from:
- vestibular system
- cerebral cortex
- spinal cord
- deep brain structures
These afferents go to the cerebellar cortex and the deep cerebellar nuclei via inferior and middle peduncles.

Question 14

Efferents of the cerebellum

Answer 14

Efferents come from:
- Purkinje cells (inhibitory)
- deep cerebellar nuclei

Purkinje cells to vestibular nuclei: bilateral
Efferents via the inferior cerebellar peduncles: bilateral posture and balance
Efferents to the superior cerebellar peduncle: decussate to their target areas and contribute to the corticospinal tract.
- damage causes ipsilateral symptoms

Question 15

Cerebellar connections

Answer 15

Midline: vermal: trunkal muscles
Lateral: hemispheric: limb muscles

Question 16

The cerebellum processes information from..

Answer 16

the ipsilateral body and contralateral cerebral cortex

Question 17

Which sensory systems give input to the cerebellum?

Answer 17

The specialized receptors, muscle spindles, and Golgi tendon organs (GTOs), unique to muscles and tendons, respectively, collect and send sensory information about the position and movement of the body’s parts to the cerebellum via the ascending sensory pathways to the cerebellum

Question 18

What other structures send input to the cerebellum?

Answer 18

Motor cortex - about impending and desired movements
Visual system - helps the cerebellum to aim movement in the desired direction
Auditory system - auditory guidance of movement
Vestibular system - orientation and motion of head, so that it can continuously make corrections to maintain or regain balance

Question 19

Where does the cerebellum primarily send output?

Answer 19

thalamus

Question 20

What are the main sources of cerebellar afferents?

Answer 20

The vestibular system (vestibular ganglion and nuclei), which terminates in the vestibulocerebellum.
The spinal cord, which terminates in the spinocerebellum.
The cerebral cortex, mostly via the corticopontocerebellar pathway but also via the corticoreticulocerebellar and cortico-oliveocerebellar pathways, all of thich terminate in the cerebrocerebellum.

Question 21

What is the name given most afferents? Are they excitatory or inhibitory?

Answer 21

Mossy fibers
They are excitatory and release glutamate
They arise from the vestibular system, spinal cord, and cerebral cortex via the brainstem

Question 22

A lesion of the cerebellum results in symptoms that appear on the ___ side of the body.

Answer 22

ipsilateral (same)

Question 23

What is the result of a lesion of the cerebellum?

Answer 23

Abnormal execution of a motor task and not deficits in motor function such as paralysis or paresis
Hypotonia - decreased muscle tone
Ataxia - uncoordinated movement; other parts of the brain may “take over” and compensate for any cerebellar deficits

Question 24

Flocculonodular syndrome

Answer 24

Characterized by the inability to maintain equilibrium and truncal ataxia, unsteady walking, swaying from side to side, tendency to fall. The individual appears inebriated. May experience nystagmus. Symptoms may be bilateral.

Question 25

Disorders following a lesion in the vermal and paravermal zones

Answer 25

Results in abnormal stance and gait with feet -positioned far apart, providing a compensatory broad base and unable to walk in tandem
Exhibits titubation (rhythmic tremor) of the trunk or head when sitting or standing, and postural changes of the head, in which the head may be held in a rotated position or tilted towards one side
- The side in which the head is rotated or tilted may not be a reflection of the side of the lesion
Abnormal eye movement such as spontaneous nystagmus, that occurs without stimulation of the vestibular apparatus

Question 26

Disorders following lesions in the hemispheric zone

Answer 26

Exhibited primarily as ataxia and tremor on the ipsilateral side of the body
Abnormal cerebellar output to the motor cortex via the thalamus, resulting in an abnormal execution of voluntary movement mediated by the corticospinal and corticorubral-rubrospinal tracts