Cerebellum

Question 1

What is the main function of the Cerebellum?

Answer 1

To smoothly coordinate ongoing movements and participate in motor planning.

Question 2

How does the Cerebellum exert its influence on movement?

Answer 2

Through connections to motor systems of the cortex and brainstem (it has no direct connections to lower motor neurons).

Question 3

Where is the Cerebellum located anatomically?

Answer 3

It is the main occupant of the posterior cranial fossa, inferior to the tentorium cerebelli.

Question 4

What is the surface of the Cerebellum characterized by?

Answer 4

Transverse ridges called folia, separated by grooves called fissures.

Question 5

What are the three lobes of the Cerebellum, divided by transverse fissures?

Answer 5

1. Anterior lobe , 2. Posterior lobe , 3. Flocculonodular lobe.

Question 6

Which fissure separates the anterior lobe from the posterior lobe?

Answer 6

The Primary fissure.

Question 7

Which fissure separates the flocculonodular lobe from the body of the cerebellum?

Answer 7

The Posterolateral fissure.

Question 8

What lies immediately anterior to the Cerebellum?

Answer 8

The Fourth ventricle.

Question 9

What are the three longitudinal zones (functional divisions) of the Cerebellum?

Answer 9

1. Midline vermis , 2. Intermediate (paravermal) zone (part of hemisphere) , 3. Lateral hemisphere.

Question 10

What structure connects the two flocculi in the flocculonodular lobe?

Answer 10

The midline nodulus (inferior end of the vermis).

Question 11

What happens if the cerebellar tonsils herniate through the foramen magnum?

Answer 11

They can compress the medullary respiratory centers.

Question 12

What connects the Cerebellum to the dorsal aspect of the pons and rostral medulla?

Answer 12

Three white matter bundles called cerebellar peduncles (superior, middle, and inferior).

Question 13

Which cerebellar peduncle mainly carries output signals?

Answer 13

The Superior peduncle (also called brachium conjunctivum).

Question 14

Which cerebellar peduncle carries input signals from the pons?

Answer 14

The Middle peduncle (also called brachium pontis).

Question 15

Which cerebellar peduncle mainly carries input signals and is also called the restiform body?

Answer 15

The Inferior peduncle (restiform body means “ropelike body”).

Question 16

Where does the superior cerebellar peduncle decussate (cross)?

Answer 16

In the midbrain at the level of the inferior colliculi.

Question 17

What is the deep structure of the Cerebellum composed of (from superficial to deep)?

Answer 17

Cerebellar Cortex (Grey Matter), Cerebellar Medulla (White Matter), and Cerebellar nuclei (deep within the white matter).

Question 18

What are the three layers of the Cerebellar Cortex?

Answer 18

1. Outer molecular layer , 2. Central layer of Purkinje cells , 3. Inner granular layer.

Question 19

What kind of cell is the only source of output signals from the Cerebellar Cortex?

Answer 19

Purkinje cells (their axons carry the only cerebellar output signals).

Question 20

Where do Purkinje cell axons mainly convey their signals to?

Answer 20

The deep cerebellar nuclei (or Roof Nuclei) and vestibular nuclei.

Question 21

What are the four deep cerebellar nuclei (from lateral to medial)?

Answer 21

Dentate, Emboliform, Globose, Fastigial (Mnemonic: Don’t Eat Greasy Food).

Question 22

What is the function of the deep cerebellar nuclei in relation to input signals?

Answer 22

They receive collateral fibers of cerebellar inputs on their way to the cerebellar cortex.

Question 23

What are the two major types of input nerve fibers to the Cerebellum?

Answer 23

Mossy fibers and Climbing fibers.

Question 24

What is the origin and target of Mossy fibers?

Answer 24

Arise mainly from pontine nuclei (via the Middle Peduncle) and synapse with granule cells.

Question 25

What is the origin and target of Climbing fibers?

Answer 25

Arise from the inferior olivary nucleus (via the Inferior peduncle) and synapse directly with Purkinje cells (PCs).

Question 26

Where does the Corticopontocerebellar tract (a major input) originate and enter the Cerebellum?

Answer 26

Originates from the Cerebral cortex (mostly contralateral), projects via Pontine Nuclei, and enters the Cerebellum via the contralateral Middle peduncle.

Question 27

What part of the Cerebellum receives Somatosensory/Spinocerebellar input from the spinal cord (ipsilaterally)?

Answer 27

The Vermis and Medial Hemisphere (intermediate zone).

Question 28

Where does Vestibular input mainly project in the Cerebellum?

Answer 28

The Flocculonodular lobe and the inferior part of the Vermis.

Question 29

What functional zone of the Cerebellum projects its output via the Dentate nucleus?

Answer 29

The Lateral zone of the hemisphere.

Question 30

What is the output of the Dentate nucleus mainly involved in?

Answer 30

Motor planning (relays to contralateral Motor cortex and association cortex).

Question 31

What functional zone of the Cerebellum projects its output via the Interposed nuclei (Emboliform and Globose)?

Answer 31

The Intermediate zone.

Question 32

What is the output of the Interposed nuclei mainly involved in?

Answer 32

Control of limb movements (arms and legs on the same side, via contralateral motor cortex/pyramidal tract or contralateral red nucleus/rubrospinal tract).

Question 33

What functional zone projects its output via the Fastigial nucleus?

Answer 33

The Vermis (and Flocculonodular lobe).

Question 34

What is the output of the Fastigial nucleus mainly involved in?

Answer 34

Posture and gait control (trunk muscles via the Medial motor system) and vestibular nuclei (balance and eye movements).

Question 35

What is the side-effect of a cerebellar lesion?

Answer 35

Ataxia (impaired coordination of movement), which is ipsilateral to the side of the lesion.

Question 36

What type of ataxia is caused by a lesion to the Vermis or Flocculonodular lobes (midline lesions)?

Answer 36

Truncal ataxia (unsteady gait) and eye movement abnormalities.

Question 37

What type of ataxia is caused by a lesion lateral to the cerebellar vermis?

Answer 37

Appendicular ataxia (ataxia of the limbs).

Question 38

What are the three main arteries supplying the Cerebellum?

Answer 38

1. Superior Cerebellar Artery (SCA), 2. Anterior Inferior Cerebellar Artery (AICA), 3. Posterior Inferior Cerebellar Artery (PICA).

Question 39

Which artery supplies the lower half of the Cerebellum and the entire vestibulocerebellum?

Answer 39

PICA (Posterior Inferior Cerebellar Artery, branch of the Vertebral artery).

Question 40

Which artery supplies most of the upper half of the Cerebellum, including the deep nuclei and superior vermis?

Answer 40

SCA (Superior Cerebellar Artery, branch of the Basilar artery).

Question 41

Which artery supplies the middle cerebellar peduncle and part of the anterior cerebellum?

Answer 41

AICA (Anterior Inferior Cerebellar Artery, branch of the Basilar artery).