1. CEREBELLUM
Functional anatomy

2. Location of cerebellum:
• Largest part of hindbrain
• Occupies most of posterior cranial fossa
• Lies behind pons & medulla
– forming roof of 4th ventricle
• Separated from posterior part of cerebrum
– by tentorium cerebelli

5. Important facts
• The hemispheres, vermis, flocculus, nodule,
and tonsil are major landmarks of the
cerebellar cortex.
• Afferent fibers end in the three-layered
cerebellar cortex. The Purkinje cells have
axons that end in the cerebellar nuclei.

6. • Motor part of the brain, serving to maintain
equilibrium and coordinate muscle
contractions.
• Makes a special contribution to synergy of
muscle action (i.e., to the synchronized
contractions and relaxations of different
muscles that make up a useful movement).

7. • Ensures that contraction of the proper
muscles occurs at the appropriate time, each
with the correct force.
• Participates in learning patterns of neuronal
activity needed for carrying out movements
and in the execution of the encoded
instructions.

8. • Imagined movements are accompanied by an
increase in cerebellar blood flow that is larger
than the increase detected in the motor areas
of the cerebral cortex.
• Evidence also suggests that the cerebellum
has sensory and cognitive functions.

9. • The cerebellum consists of a cortex, or surface
layer, of gray matter contained in transverse
folds or folia plus a central body of white
matter.
• Four pairs of central nuclei are embedded in
the cerebellar white matter.
• Three pairs of cerebellar peduncles,
composed of myelinated axons, connect the
cerebellum with the brain stem.

12. Cerebral peduncles:
• Joined to the brain stem via:
• Superior cerebellar peduncle –> Midbrain
• Middle cerebellar peduncle –> Pons
• Inferior cerebellar peduncle –> Medulla

15. Major contents of the cerebellar peduncles. For
simplicity, the inferior cerebellar peduncle is depicted
as containing only climbing fibers

16. Contents of Cerebellar Peduncles
• The superior cerebellar peduncle contains
cerebellar efferent fibers, the ventral
spinocerebellar tract, and tectocerebellar
fibers.
• The middle cerebellar peduncle consists of
fibers from the contralateral pontine nuclei

17. Contents of Cerebellar Peduncles
• Inferior cerebellar peduncle contains
olivocerebellar and dorsal spinocerebellar
fibers and the vestibulocerebellar and
fastigiobulbar connections.

23. Microstructure

25. Microscopic structure of cerebellar
cortex (3 layers
• External Molecular layer
• Middle Purkinje layer
– large flask shaped neurons
– arranged in single tier in a plane transverse to
folium
– dendrites produce profuse branching
– receive communications afferent fibres entering
cerebellum

26. – axons run to DEEP CEREBELLAR NUCLEI
• sole output of cerebellar cortex
– functionally
• inhibitory (GABA)
– Stimulate Purkinje cells, inhibits deep nuclei
• Internal Granular layer
– closely packed small neurons

28. All afferent input via 2 different fibres
• Mossy fibres
– entire inflow of cerebellum
• except from inferior olive
• particularly from cerebral cortex via pons
– they synapse in expanded MOSS-like appearance
with granule & Golgi cells in granular layer
– fast-firing
• rapid adjustment for ongoing movement

29. • Climbing fibres
– inflow from inferior olive
– run up and synapse with dendrites of single
Purkinje cell
– slow-firing
• helps in learning muscle habits

31. Origin of climbing fibers from the inferior olivary nucleus. The
axon of each olivary neuron has several branches, each of which
forms the single climbing fiber of one Purkinje cell.

33. • The fastigial, interposed, and dentate nuclei
receive branches of all cerebellar afferent
fibers and the output of the cortex.
• These nuclei contain the cerebellar efferent
neurons.

36. • The vestibular system is connected
ipsilaterally with the vestibulocerebellum,
which comprises the flocculonodular lobe and
the fastigial nucleus.
• This nucleus projects to the ipsilateral
vestibular nuclei and to the reticular
formation

37. • Proprioceptive signals are carried ipsilaterally
to the spinocerebellum, which consists of
vermis, paravermal zones, and interposed
nuclei.
• These nuclei project to the contralateral red
nucleus and to the posterior division of the
contralateral ventrolateral (VLp) thalamic
nucleus. The VLp projects to the primary
motor cortex.

38. Connections of vestibulocerebellum and vestibular nuclei.
Afferents-blue; efferents-red;neurons-black

39. Connections of spinocerebellum and vestibular nuclei.
Afferents-blue; efferents-red;neurons-black

40. Connections of pontocerebellum. Afferents-blue; efferents-red;neurons-
black