Lecture 3: The Cerebellum Flashcards
How does the cerebellum differ from the cerebral cortex?
Two other ways it differs from the cerebral cortex:
1. None of its activity directly contributes to consciousness
2. Its hemispheres possess ipsilateral representation of body parts.
Finer arrangement of transverse gyri “folia” and sulci gives greater expansion of surface area compared to cortex
What is the anatomical position of the cerebellum?
Develops from the?
Cerebellum affects movement on which Side of the body?
• In posterior cranial fossa.
• Inferior to the cerebrum, under the tentorium cerebelli
• Posterior to the pons and medulla oblongata
• Posterior/ superior border of the 4th ventricle
-develops from the metancephalon
-attached to brainstorm by 3 cerebellar peduncles.
-affects movement on ipsilateral side of body
Label the diagram of the cerebellum on slide 5, 6 and 7
The cerebellum is very small at birth but develops rapidly in the first 6 years
Yeh
The cerebellum
- develops from the?
- located in the?
- how is it attached to the brainstem?
- forms the roof of what?
- it is separated from the occipital and temporal loves by the?
- consists of ____and ____on its surface
- made up of 2
- ___% mass of brain and ____% of total neurons
- part of what system?
- cerebellum affects movement on same or opposite side of the body?
- how does the cerebellum coordinate movements?
- what does it monitor?
- it has input from what system? To monitor position of body?
Develops from metencephalon.
• Located in posterior cranial fossa.
• Attached to brainstem by 3 cerebellar peduncles.
• Forms roof of 4th ventricle.
• Separated from occipital and temporal lobes by tentorium cerebelli.
• Consists of folia and fissures on its surface.
• Made up of two lateral lobes = cerebellar
hemispheres.
• 10% mass of brain, 50% of total neurons.
Part of motor system.
• Cerebellum indirectly affects movements on
ipsilateral (same side) of the body.
• Coordinates complex movements by comparing motor commands with actual body movements and adjusting to improve accuracy & timing.
• Monitoring and feedback in real-time and most important at end stages of movement.
• Inputs from vestibular system so it can monitor position of body in space.
What are the 3 primary functions of the cerebellum?
Three primary functions:
- maintenance of posture and balance
- maintenance of muscle tone
- Coordinates smooth movements by influencing timing and force of contractions of voluntary muscles.
Cerebellar lobes
Function of the anterior lobe?
• Anterior to primary fissure.
• Maintains coordination of limb movements wile
movements are being executed.
• Receives input from limb (chiefly lower limb) muscle spindles (stretch receptors) and Golgi tendon organs via the spinocerebellar tracts.
• Role in regulation of muscle tone.
• TEST FOR LESION: Heel-shin test=> Slide heel of one foot smoothly down shin of other leg.
Cerebellar lobes
Function of the flocculonodular lobe?
Flocculonodular lobe (vestibulocerebellum):
• Consists of nodulus (of the vermis) and the flocculus (most ancient part of cerebellum).
• Receives input from vestibular system so it can monitor the position of the body in space.
• Play a role in maintenance of posture and balance and eye movements.
Cerebellar lobes
Posterior lobe function?
• Lies between primary fissure and posterolateral fissure.
• Receives massive input from cerebral cortex.
• Plays role in co-ordination of voluntary motor
activity.
• Stores all sequential components of skilled movements.
Label the shit out of slide 17 and 19
Ye
What is a peduncle?
What is the function of the superior cerebellar peduncle?
Middle cerebellar peduncle?
Inferior cerebellar peduncle?
Tracts of afferent & efferent axons enter or leave the cerebellum through the cerebellar peduncles.
• Superior cerebellar peduncle: connects cerebellum to pons and midbrain.
• Middle cerebellar peduncle: connects the cerebellum to the pons.
• Inferior cerebellar peduncle: connects the cerebellum to the medulla.
Tracts of afferent & efferent axons enter or leave the cerebellum through the cerebellar peduncles.
• Superior cerebellar peduncle: connects cerebellum to pons and midbrain.
• Middle cerebellar peduncle: connects the cerebellum to the pons.
• Inferior cerebellar peduncle: connects the cerebellum to the medulla.
Name the afferent tracts and what they do
Dorsal spinocerebellar tract: carries proprioceptive information from muscles spindles and tendon organs of individual lower limb muscles to the cerebellum via inferior cerebellar peduncle.
• Cuneocerebellar tract: carries equivalent information from upper limb which also enters via inferior cerebellar peduncle.
• Trigeminocerebellar tract: carries info from
TMJ, masticatory and external ocular muscles.
• Ponto-cerebellar tract: carries info from motor cortex to cerebellum through contralateral middle cerebellar peduncle.
• Vestibulocerebellar tract: vestibulocerebellar impulses from vestibular nuclei carry info about position and movement of head and enter cerebellum through inferior cerebellar peduncle.
What is the cerebellar nuclei and what do they do?
What are the 4 main nuclei?
Cerebellar nuclei
• Contain most of the cell bodies of EFFERENT neurons of the cerebellum.
• Receive projections from Purkinje cells in cerebellar cortex.
• Four nuclei containing most of efferent neurons:
• Dentate nucleus
• Emboliform nucleus
• Globose nuclei
• Fastigial nucleus
Interposed nuclei all the above
Purkinje cell axons project to cerebellar nuclei based on their position:
• Dentate nucleus (most lateral, largest – input from lateral parts of hemispheres)
• Emboliform nucleus
• Globose nucleus
• Fastigial nucleus (most medial – input from vermis & flocculonodular lobes)
• Cerebellar nuclei project to motor centres of the thalamus, brainstem and spinal cord.
Describe the layers of the cerebellar cortex
Molecular layer (outer layer) • Purkinje cell layer
• Granular layer
• White matter of cerebellum deep to granular layer contains cerebellar nuclei.
Slide 29 and 30
What is the blood supply to the cerebellum?
• Cerebellum supplied by 3 large arteries:
• Posterior inferior cerebellar artery (PICA)
• Anterior inferior cerebellar artery (AICA)
• Superior cerebellar artery (SCA)
Side 33 for image
- Does the cerebellum initate movements?
- What type of fibres (afferent/efferent) does the superior cerebellar peduncle carry?
- What type of information does the spinocerebellar tract carry?
- Which is the most superficial layer of the cerebellar cortex?
- Which is the largest cerebellar nucleus?
Yep
