Histology of cerecellum

1. Osh State University
International Medical Faculty
Cerebellum & Cerebral Cortex
Submitted to : Ulkan Mam
Submitted by : Abdullah, Rahul, Nikhat, Frazia
Group no. : INL-10B-22

2.  The cerebellum and cerebral cortex are two distinct
parts of the brain with different functions.
 Cerebellum: The cerebellum is a structure located at the
back of the brain, just above the brainstem. It is
primarily responsible for coordinating and fine-tuning
voluntary movement, balance, posture, and motor
learning. It receives information from various sensory
systems, such as the inner ear, to help maintain
equilibrium and coordinate movements. Additionally,
the cerebellum is involved in cognitive functions like
attention, language processing, and certain aspects of
memory.

3.  The cerebellum and cerebral cortex are two distinct
parts of the brain with different functions.
 Cerebral Cortex: The cerebral cortex, also known as the
neocortex, is the outermost layer of the brain and
covers the cerebrum, which is the largest part of the
brain. It is highly folded and convoluted, allowing for a
large surface area. The cerebral cortex plays a crucial
role in higher cognitive functions, including perception,
consciousness, memory, attention, language, problem-
solving, and decision-making. It is divided into various
regions called lobes, including the frontal, parietal,
temporal, and occipital lobes, each associated with
different functions.

4. Your cerebellum is a part of your brain located at the back
of your head, just above and behind where your spinal cord
connects to your brain itself. The name “cerebellum” comes
from Latin and means “little brain.”
For centuries, scientists believed your cerebellum’s job was
to coordinate your muscle movements.

7. Outer Layer (Cortex): The outer layer of the cerebellum is known as the cortex. It
consists of a highly folded and convoluted sheet of gray matter. The cortex can be
further divided into three layers:
1. a. Molecular Layer: The molecular layer is the outermost layer of the cerebellar
cortex. It contains a sparse population of small interneurons called stellate cells
and basket cells. This layer also contains the dendrites of Purkinje cells, which
extend into the molecular layer to receive inputs from other neurons.
2. b. Purkinje Cell Layer: The Purkinje cell layer is located below the molecular
layer and consists of large, flask-shaped neurons called Purkinje cells. These
are the most prominent neurons in the cerebellum. Purkinje cells have
extensive dendritic trees that form a characteristic fan-like pattern in the
molecular layer. They receive inputs from various sources and are the main
output neurons of the cerebellar cortex.
3. c. Granule Cell Layer: The granule cell layer is the innermost layer of the
cerebellar cortex. It contains a dense population of small granule cells, which
are the most numerous neurons in the brain. The axons of granule cells extend
into the molecular layer, where they form parallel fibers that run perpendicular
to the folia (the folds of the cerebellar cortex). These parallel fibers make
extensive synaptic connections with the dendrites of Purkinje cells.

8.  Deep Nuclei: Located beneath the cerebellar cortex, there
are four deep nuclei within the cerebellum:
1. a. Dentate Nucleus: The dentate nucleus is the largest
and most lateral of the deep nuclei. It receives inputs
mainly from the lateral regions of the cerebellar cortex.
2. b. Interposed Nuclei: The interposed nuclei consist of
two subdivisions: the emboliform nucleus and the
globose nucleus. They receive inputs from the
intermediate regions of the cerebellar cortex.
3. c. Fastigial Nucleus: The fastigial nucleus is the most
medial of the deep nuclei. It receives inputs from the
vermis, the midline portion of the cerebellar cortex.
 These deep nuclei serve as the major output centers of the
cerebellum. They send axons out of the cerebellum to
other brain regions, including the thalamus and brainstem,
to influence motor control and other functions.

11.  Motor Coordination: The cerebellum is primarily responsible for
coordinating voluntary movements and maintaining muscle tone and
posture. It receives input from the sensory systems, such as the inner
ear, to integrate sensory information and fine-tune motor output. This
coordination enables smooth, precise, and coordinated movements.
 Balance and Equilibrium: The cerebellum plays a crucial role in
maintaining balance and equilibrium. It receives information from
sensory organs like the inner ear and helps adjust body posture and
position to ensure stability during standing, walking, and other
activities.
 Motor Learning and Skill Acquisition: The cerebellum is involved in
motor learning processes. It helps in the acquisition and refinement of
motor skills, such as playing a musical instrument or riding a bicycle. It
receives feedback about the outcome of motor actions and makes
necessary adjustments to improve future performance.
 Cognitive Functions: Although traditionally associated with motor
control, the cerebellum also contributes to certain cognitive functions. It
has connections with the cerebral cortex and is involved in attention,
language processing, working memory, and aspects of executive
functions.

12. Your cerebral cortex is the outer layer that lies on
top of your cerebrum. Your cerebrum is the largest
area of your brain. Your cerebrum divides your brain
into two halves called hemispheres. The hemispheres
are attached by a bundle of nerve fibers called the
corpus callosum.

14.  Microscopically, the cerebral cortex is composed of cell
bodies of billions of neurons, their dendrites, myelinated
and unmyelinated axons which altogether form a unique,
multilayered arrangement.
 In addition, it contains a dense population of
supporting glial cells which include
oligodendrocytes, astrocytes, microglia, and ependymal
cells, and blood vessels. The neuronal cells of the cortex
consist of six main cell types:
 These are the pyramidal cells (the main output neurons of
the cerebral cortex), fusiform cells, stellate (granular)
cells, basket cells, horizontal cells of Cajal-
Retzius and cells of Martinotti. Histologically, the cerebral
cortex is organized into six layers or horizontal laminae
based on the size and shape of the neuronal bodies.

15.  These layers are designated by Roman numerals, and
from superficial (at the pial surface) to deep, they are the:
 Molecular (plexiform) layer (I): Contains mainly nerve axons
and a few scattered horizontal cells of Cajal-Retzius
 External granular layer (II): Composed of a varying density
stellate (granular) cells and pyramidal cells
 External pyramidal layer (III): Contains predominantly
pyramidal cells of varying sizes
 Internal granular layer (IV): Consists mostly of the stellate
cells and a smaller portion of the pyramidal cells. It is usually
the narrowest layer
 Internal pyramidal layer (V): Contains mainly medium-sized
to large pyramidal cells
 Multiform (fusiform) layer (VI): Composed different types of
neuron types, mostly fusiform cells with less dominant
pyramidal cells and interneurons

18.  Additionally, the cerebral cortex can be divided into
three functional areas:
 primary, secondary and associative.
 The cortical areas responsible for the elementary
functions of either motor or sensory are primary
areas. Secondary areas are located around every
primary area and receive afferent projections from
the corresponding primary areas and the thalamus.
They are responsible for integrating the raw signal
from the primary areas with the information received
from the thalamus, to refine the primary area stimuli.
Association areas, on the other hand, are cortical
areas that integrate, process and analyze different
kinds of stimuli that reach the brain and are involved
in mediating higher mental functions.

20.  Sensory Perception: Different regions of the cerebral cortex process
sensory information from various senses, such as vision, hearing,
touch, taste, and smell. These sensory areas help in perceiving and
interpreting the external environment.
 Motor Control: The cerebral cortex contains the primary motor
cortex, which is responsible for initiating voluntary movements. It
sends signals to the muscles and coordinates motor actions based
on information from other brain areas, including the cerebellum.
 Cognitive Functions: The cerebral cortex is closely associated with
higher cognitive functions. Different regions of the cortex are
involved in memory, attention, language processing, problem-
solving, decision-making, creativity, and emotional regulation. For
example, the prefrontal cortex is crucial for executive functions like
planning, reasoning, and self-control.
 Consciousness and Awareness: The cerebral cortex is involved in
generating and maintaining conscious awareness. It allows us to be
aware of our surroundings, ourselves, and engage in introspection
and self-reflection.