HISTOLOGICAL FEATURES OF

CEREBRUM

CEREBELLUM

Prof.J.Anbalagan

CEREBELLUM

CEREBELLUM • Hind brain-

– small brain

• Posterior cranial fosse

• Forms roof of IV ventricle

• Fissures and folia

CEREBELLUM

• Receives sensory data

– Same side spinal cord

– Dorsal and ventral spinocerebellar tract

• Receives Motor data

– from cerebrum opposite side

– Cortico pontine fibers

• Output is motor in function

CEREBELLUM

• Cerebellum – controls the activity of cerebrum and

spinal cord

–dysfunctions • manifested by disturbances in the motor

functions without voluntary paralysis

• Resulted in clumsy, poorly coordinated

loss of skillful movements

CEREBELLUM-Functions

• Responsible for Equilibrium Controls eye and head movements balancing

Postural changes Muscle tone

Smooth execution of voluntary

movements Accuracy Perfection control

White fibers - afferent

• Mossy fibers – Spinal cord

– Vestibular nucleus

– Pons

• Enters through inferior and middle cerebellar peduncle

• Synopses with Purkinje cells through granular cells

White fibers- afferent

• Climbing fibers

– Olivary nucleus

– Accessory olivary nucleus

• Through inferior peduncle

• Enters directly to molecular layer

• Synapses with Purkinje 1:1

White fibers - efferent

• Axons of Purkinje

( except archicerebellum)

• Deep nuclei of cerebellum

• Through superior cerebellar peduncle

Cerebellum-cortex • Pia mater

• Cortex and white fibers

• Cortex-Three layers

• Type of cells

– Stellate cells – Basket cells – Purkinje cells – Granule cells – Golgi type II

• White fibers

– Climbing fibers – Mossy fibers

CEREBELLUM • Layers of cerebellum

• Molecular layer – Dendrite orborization – Densely packed axons run

parallel to surface – Superficially stellate cells – Deeper stellate cells

known as basket cells

• Purkinje layer

• Granular layer – Closely packed granule

cells – Shows clear zones -

glomeruli

CEREBELLUM

PURKINJE NEURON

Stellate cells

Basket cell

CEREBELLUM-GOLGI STAIN

PURKINJEE NEURONS

Cerebellum-dendrite tree

Cerebellum-granular layer-(rosette)

Molecular layer

Granular layer

Purkinje layer

CEREBELLUM MOLECULAR

LAYER

GRANULAR

LAYER

MOLECULAR LAYER

GRANULAR LAYER

PURKINJE LAYER

Cerebrum

• White matter

–Nerve fibers

• Commissural

• Association

• Projection

• Gray matter

–Neurons

–Neuroglia cells

Cerebral cortex- type of neurons

• Six type of neurons • Pyramidal

– Triangular

– Dendrite arises from three angles

– Axon from the base of cell

– Prominent nucleus and Nissl substances

– Small sized pyramidal neuron10-12 micron

– Medium sized neuron 40-50 micron

– Large sized (Betz cells ) > 100 micron

• Stellate/granular cells – Polygonal/triangular

shape

– Dark condensed nucleus

– Dendrites arises all over

– Axon terminate next layer and goes deeper

• Fusiform cells – Oriented perpendicular

to the surface

– One dendrites towards superficially

– One axon towards deeper layer

STELLATE

F

U

S

I

F

O

R

M

• Horizontal cells of Cajal

– Spindle shaped

– Parallel to the surface

– Internuncial type

• Cell of Mortinotti

– Small triangular cells

– Axons goes towards surface

• Golgi type II

– Process ends close to cell body

– Local circuit

CAJAL

MORTINOTTI

GOLGI

Layers of cerebral cortex • Outer Molecular layer

– Horizontal cells + Golgi type II

– Tangential nerve fibers from pyramidal, fusiform and cells of Mortinotti

• Outer granular layer – Small pyramidal cells + stellate

cells

– Dendrites end in first layer

– Axons forms association

• Outer pyramidal layer – Medium and large pyramidal cells

– Axons forms association and commissural fibers

OM

OP

OG

• Inner granular layer – Packed stellate cells – Lot of fibers as band-

Outer band of Baillarger

• Inner pyramidal/ganglion – Large Betz cells – Axons continues as

projection fibers – Horizontal fibers forms

inner band of Baillarger

• Multiform layer/fusiform cells – Spindle shaped cells – Granular, fusiform and

stellate type

Outer band

Inner band

Molecular layer

Outer granular layer

Outer pyramidal layer

Inner granular layer

Inner pyramidal layer

Pleomorphic layer

Pyramidal neuron

Cerebrum-cortex

G