Cerebellum

Question 1

What are the functions of the cerebellum?

Answer 1

Coordinating movements, maintaining posture, motor learning, and procedural memory

Question 2

What is the molecular layer of the cerebellum?

Answer 2

Lies next to pial surface and has a few neurons; cell bodies of basket cells and stellate cells are there

Question 3

What is the purkinje layer of the cerebellum?

Answer 3

Contains purkinje cell bodies

Question 4

What is the granular layer of the cerebellum?

Answer 4

Deepest layer; contains granule cells and a few golgi cells

Question 5

What is the white matter of the cerebellum?

Answer 5

Axons of neurons

Question 6

What are purkinje cells?

Answer 6

Output cells from cerebellar cortex; inhibit the cerebellar nuclei and the vestibular nuclei; neurotransmitter is GABA; highly differentiated with many dendrites

Question 7

What are granule cells?

Answer 7

Smallest neurons; only excitatory neurons; neurotransmitter is glutamate

Question 8

What are stellate cells?

Answer 8

Their axons synapse only with purkinje cells and inhibit them; star-shaped dendrites

Question 9

What are golgi cells?

Answer 9

Inhibitory neurons; neurotransmitter is GABA; large scattered neurons with short axons

Question 10

What are basket cells?

Answer 10

Their axons synapse with purkinje cells and inhibit them; neurotransmitter is GABA

Question 11

What are the types of afferent fibers in the cerebellum?

Answer 11

Climbing and mossy fibers

Question 12

What are climbing fibers?

Answer 12

From inferior olive; myelinated with excitatory influence on purkinje cells; convey info regarding movement errors to the cerebellum

Question 13

What are mossy fibers?

Answer 13

From spinal cord, reticular formation, vestibular system, and pontine nuclei; synapse with granulocytes; convey somatosensory, arousal, equilibrium, and cerebral cortex motor info to cerebellum

Question 14

What are the functional divisions of the cerebellum?

Answer 14

Archicerebellum/vestibulocerebellum, paleocerebellum/spinocerebellum, and neocerebellum/pontocerebellum

Question 15

What is the vestibulocerebellum?

Answer 15

Functional name for flocculonodular lobe; receives info directly from vestibular receptors; sends output to the vestibular nuclei; also receives info from visual areas; functions to influence eye movements and postural muscles of head and body

Question 16

What is the spinocerebellum?

Answer 16

Functional name for vermis and paraventral region; somatosensory info, internal feedback from spinal interneurons and sensorimotor cortex; functions to control ongoing movement via the brainstem descending tracts; axial and lower extremity movements as well as gait and station

Question 17

What is the pontocerebellum?

Answer 17

Input from cerebral cortex (premotor, sensorimotor, and others) via pontine nuclei; functions in coordination of voluntary movements, planning of movements, and timing (mainly upper extremity)

Question 18

What are the afferent pathways entering the cerebellum?

Answer 18

Vestibular system (vestibular nuclei, cranial nerve VIII), anterior/posterior spinocerebellar tract, cuneocerebellar tract, cortico-pontocerebellar, cortico-olivocerebellar, and cortico-reticulocerebellar tracts

Question 19

What axons are in the posterior spinocerebellar tract?

Answer 19

Axons carrying unconscious proprioception from lower limb

Question 20

What axons are in the cuneocerebellar tract?

Answer 20

Axons carrying unconscious proprioception from upper limb

Question 21

Describe the superior cerebellar peduncle

Answer 21

Major efferent route from the globose, emboliform, and dentate nuceli; afferent fibers from ventral spinocerebellar tract run here too

Question 22

Describe the middle cerebellar peduncle

Answer 22

Largest peduncle; afferent fibers from pontine nuclei relayed to cortex

Question 23

Describe the inferior cerebellar peduncle

Answer 23

Primarily afferent pathways from spinal cord

Question 24

What nuclei are considered deep nuclei?

Answer 24

Fastigial, globose, emboliform, and dentate

Question 25

Describe ataxia as it relates to the cerebellum

Answer 25

Common to all lesions of cerebellum; voluntary, normal strength, jerky, and inaccurate movements not associated with hyperstiffness

Question 26

Unilateral lesions in the cerebellum affect the _________ side

Answer 26

Ipsilateral

Question 27

What do lesions of the vestibulocerebellum (connections between vestibular system and flocculonodular lobe) cause?

Answer 27

Nystagmus, truncal ataxia (difficulty maintaining sitting and standing balance), and truncal instability (titubation, can't tandem walk)

Question 28

What do lesions in the spinocerebellum cause?

Answer 28

This is where connections between the cutaneous and proprioceptive information coming from the spinal cord to the vermis and paravermis regions; causes gait and truncal ataxia (wide base, staggering base)

Question 29

What are midline ataxias? Give examples

Answer 29

Ataxic syndromes caused by vestibulocerebellar and spinocerebellar disease; truncal instability and equilibratory (gait) ataxias

Question 30

What is truncal instability (titubation)?

Answer 30

Tremor of the trunk in an anterior-posterior plane at 3-4 Hz

Question 31

What is equilibratory (gait) ataxia?

Answer 31

Wide based, irregular steps with lateral veering

Question 32

What do lesions of the cerebrocerebellum cause?

Answer 32

Dysarthria (slurred, poorly articulated speech), ataxic gait, decomposition of movements

Question 33

How do limb ataxias manifest?

Answer 33

Dysdiadochokinesia, dysmetria, and action tremors

Question 34

What is dysdiadochokinesia?

Answer 34

Inability to rapidly alternate movements

Question 35

What is dysmetria?

Answer 35

Inability to accurately move an intended distance

Question 36

What is an action tremor?

Answer 36

Shaking of the limb during voluntary movement

Question 37

What do you find in someone with appendicular ataxia?

Answer 37

Hypotonia, decompositon of movement, dysmetria (inability to accurately move an intended distance), and dysdiadochokinesia

Question 38

Compare and contrast cerebellar ataxia and sensory ataxia

Answer 38

Cerebellar: romberg test positive, unable to stand with feet together with or without eyes open, normal vibratory sense, proprioception and ankle reflexes Sensory: can stand with feet together with eyes open, but not closed (positive romberg test) but abnormal vibratory sense, proprioception, and ankle reflexes

Question 39

What exams/observations should you make when examining the vestibulocerebellum and spinocerebellum?

Answer 39

Station, walking, tandem gait

Question 40

What exams/observations should you make when examining the cerebrocerebellum?

Answer 40

Rapid alternating movements, finger-to-nose, toe-to-finger, heel-to-shin, rebound and check reflex, and speech