Chapter 6 - Cerebellum

Question 1

Where is the cerebellum located?

Answer 1

• hind brain
• at the posterior cranial fossa
• inferior to the tentorium cerebelli (the cerebellum is covered superiorly by the tentorium cerebelli)

Question 2

Enumerate the neighbors of the cerebellum

Answer 2

1) superiorly: tentorium cerebelli
2) anteriorly: fourth ventricle, pons, and medulla oblongata

Question 3

The ovoid cerebellum is divided into (1) by a narrow median constriction called (2)

Answer 3

(1) right and left cerebellar hemisphere
(2) vermis

Question 4

The cerebellum is connected to the posterior part of the brainstem by 3 symmetrical bundles of nerve fibers namely:

Answer 4

1) superior cerebellar peduncle
2) middle cerebellar peduncle
3) inferior cerebellar peduncle

Question 5

Lobes of the cerebellum

Answer 5

1) anterior lobe
2) middle/ posterior lobe
3) flocculonodular lobe

lobes are separated by the following fissures:
* primary fissure
* uvulonodular fissure

Question 6

The anterior lobe of the cerebellum that may be seen superiorly is separated from the middle lobe by a wide V-shaped fissure called

Answer 6

Primary Fissure

Question 7

The largest part of the cerebellum

Answer 7

Middle lobe or Posterior lobe

situated between the primary and uvulonodular fissures

Question 8

Cerebellum

Separates the middle lobe and the flocculonodular lobe

Answer 8

Uvulonodular fissure

Question 9

Lobes of the Cerebellum

Memorize

Answer 9

Question 9

Lobes of the Cerebellum

Memorize

Answer 9

Question 10

Deep fissure separating the superior from the inferior surfaces of the cerebellum

Has no morphologic or functional significance

Answer 10

Horizontal fissure

Question 11

Cortical arrangement of the cerebellum

Answer 11

• outer cortex - gray matter
• inner white matter
• embbeded gray matter in the inner white matter (intracerebellar nuclei)

Question 12

The cut surface branched appearance when a section made through the cerebellum parallel with the median plane that divides the folia at right angles is called

Answer 12

Arbor vitae

means “Tree of life”

Question 13

3 layers of the cerebellar gray cortex

Answer 13

(from outer to inner)
1) molecular layer
2) purkinje layer
3) granular layer

MPG

Question 14

Two types of neurons found in the cerebellar molecular layer

Answer 14

1) outer stellate cells
2) inner basket celld

Neuroglial cells are found between neurons

Question 15

Large glogi type 1 neurons that are flask shaped and are arranged in a single layer

Answer 15

Purkinje cells

found at the purkinje layer of the cerbellum gray cortex

Question 16

What are the functional areas of the cerebellum

vertically divided

Answer 16

1) vermis
2) intermediate zones
3) lateral zones

Question 17

Part of the cerebellum that influences the movements of the long axis of the body namely the neck, thorax, abdomen, and hips

Answer 17

Vermis

Question 18

Area of the cerebellum that controls the muscle of the distal body parts such as the limbs and especially the hands and feet

Answer 18

Intermediate zone

Question 19

Function of the cerebral hemisphere’s lateral zone

Answer 19

Part of the cerebral hemisphere that is concerned with the planning of sequential movements of the entire body and is involved with the conscious assesment of movement errors

Question 20

Enumerate the four masses of gray matter embedded in the white matter of the cerebellum on each side

Answer 20

From lateral to medial:
1) dentate nuclei
2) emboliform nuclei
3) globose nuclei
4) fastigial nuclei

DEG F

Question 21

Largest of the cerebellar nuclei

Answer 21

Dentate

Question 22

Largest of the cerebellar nuclei that is shaped of a crumpled bag with the opening facing medially

its white fibers form part of the superior cerebellar peduncle

Answer 22

Dentate Nuclei

Question 23

Intracerebellar nuclei

ovoid and situated medial to the dentate nucleus

Answer 23

Emboliform nucleus

Question 24

Intracerebellar nuclei

consists of one or more rounded cell groups that lie medial to the emboliform nucleus

Answer 24

Globose nucleus

Question 25

Intracerebellar nuclei

lies near the midline in the vermis and close to the roof of the fourth ventricle - larger than the globose nucleus

Answer 25

Fastigial nucleus

Question 26

(True/False)

There is a large amount fo white matter at the vermis while only a small amount of white matter in each cerebellar hemisphere

Answer 26

False

There is a small amount of white matter in the vermis - resembers a tree trunk with branches (arbor vitae)

There is a large amount of white matter in each cerebellar hemisphere

Question 27

Three groups of fibers in the cerebellar white matter

Answer 27

1) intrinsic fibers
2) afferent fibers
3) efferent fibers

Question 28

Function of cerebellar white matter intrinsic fibers

Answer 28

connects different regions of the cerebellum specifically:
* folia of the cerebellar cortex and vermis at the same side
* right and left cerebellar hemispheres

Question 29

Fibers from the dentate, emboliform, and globose nuclei leave the cerebellum through ()

Answer 29

superior cerebellar peduncle

Question 30

Fibers from the fastigial nucleus leave through ()

Answer 30

Inferior cerebellar peduncle

Question 31

Two main lines of input to the cerebellar cortex

Excitatory to the Purkinje cells

Answer 31

1) climbing fibers
2) mossy fibers

Question 32

Climbing fibers definition

Answer 32

terminal fibers of the olivocerebellar tracts

A single purkinje neuron makes a synaptic connection with only one climbing fiber while one climbing fiber makes contact with 1 to 10 purkinje neurons

Question 33

Mossy fibers definition

Answer 33

Terminal fibers of all cerebellar afferent tracts except for the olivocerebellar tract

Diffuse excitatory effect

A single mossy fiber may stimulate thousands of Purkinje cells through the granule cell

Question 34

Function of stellate, basket and golgi cells of the cerebellar cortex

Answer 34

inhibitory interneurons

limits the area of cortex excited and influences the degree of Purkinje cell excitation produced by climbing and mossy fiber input

Question 35

Forms the center of a functional unit of the cerebellar cortex

Answer 35

Purkinje cells

1. Once excited or inhibited, the Purkinje cells will send inhibitory impulses to the intracerebellar nuclei
2. the intracerebellar nuclei will modify muscular activity through motor control areas of the brainstem and cerebral cortex

Question 36

Neurotransmitters used by excitatory climbing and mossy afferent fibers

Answer 36

Glutamate

as the excitatory transmitter on the dendrites of the purkinje cells

other neurotransmitters used are norepinephrine and serotonin

Question 37

Connects the cerebellum and the midbrain

Answer 37

superior cerebellar peduncle

Question 38

Connects the cerebellum and the pons

Answer 38

middle cerebellar peduncle

Question 39

Connects the cerebellum and the medula oblongata

Answer 39

inferior cerebellar peduncle

Question 40

Cerebellar Afferent Pathways

Answer 40

Question 41

Cerebellar Efferent Pathways

Answer 41

Question 42

Cerebral functions control which side of the body?

Answer 42

Ipsilateral side

Question 43

What is ataxia?

Answer 43

Ataxia is a neurological condition that affects a person’s ability to control their voluntary movements. It can result in problems with coordination, balance, speech, and eye movements. Ataxia may be caused by various factors including genetic disorders, head injury, stroke, or certain medications. There are different types of ataxia, including hereditary ataxia, acquired ataxia, and sporadic ataxia. Treatment options for ataxia may include medications, physical therapy, and occupational therapy.

Question 44

What is dysmetria?

Answer 44

Dysmetria is a neurological condition that affects a person’s ability to accurately measure distances and control the range and direction of their movements. It is a type of ataxia and is often seen in people with cerebellar disorders. Dysmetria can cause movements to be too short or too long, resulting in clumsiness, difficulty with fine motor skills, and problems with coordination and balance. Dysmetria may be caused by a variety of factors, including genetic disorders, head injury, stroke, or certain medications. Treatment options for dysmetria may include physical therapy and occupational therapy to help improve motor skills and coordination.

Question 45

Cerebellar Signs

Answer 45

Cerebellar signs refer to a group of neurological signs that reflect dysfunction of the cerebellum, which is the part of the brain responsible for motor coordination, balance, and muscle tone. Some of the common cerebellar signs include:

1) Ataxia: Impaired coordination of voluntary movements, resulting in unsteady gait, poor balance, and difficulty with fine motor skills

2) Dysmetria: Difficulty with judging the distance and range of movements, causing over or undershooting of targets.

3) Dysdiadochokinesia: Difficulty with rapid alternating movements, such as pronation-supination or tapping movements.

4) Intention tremors: Involuntary shaking of limbs that occurs during voluntary movements.

5) Hypotonia: Reduced muscle tone, resulting in a floppy appearance of limbs.

6) Rebound phenomenon: Inability to halt movements and maintain a steady posture when resistance is suddenly removed.

7) Nystagmus: Involuntary rhythmic oscillation of the eyes.

These cerebellar signs can be caused by a variety of conditions, including genetic disorders, stroke, brain injury, and degenerative diseases. The presence of these signs can help doctors diagnose and localize the underlying neurological problem.

Question 46

What is cerebellar infarct?

Answer 46

Cerebellar infarct is a type of stroke that occurs when there is a blockage of the blood vessels supplying blood to the cerebellum, a part of the brain responsible for motor coordination, balance, and muscle tone. Cerebellar infarcts can be caused by a variety of factors, including atherosclerosis, blood clots, or emboli, and can result in symptoms such as vertigo, nausea, vomiting, dizziness, difficulty with speech, and difficulty with coordination and balance. Cerebellar infarcts can be diagnosed with imaging studies, such as CT or MRI scans, and treated with medications to dissolve blood clots or surgery to remove the blockage. Rehabilitation may also be necessary to help patients regain motor coordination and balance.