anatomy of the cerebellum

1. CEREBELLUM
DR. JAMIL ANWAR

2. The cerebellum is
situated in the
posterior cranial
fossa. It is the largest
part of the hindbrain
and lies posterior to
the fourth ventricle,
the pons, and the
medulla oblongata.

3. CEREBELLUM
 The cerebellum is located
behind the dorsal aspect of
the pons and the medulla.
 A midline portion, the
vermis, separates two
lateral lobes, or cerebellar
hemispheres.
 The cerebellum consists of
the cerebellar cortex and
the underlying cerebellar
white matter
 Four paired deep
cerebellar nuclei are
located within the white
matter of the cerebellum

4. The cerebellum is
divided into three main
lobes:
the anterior lobe
the middle(posterior)
lobe
 the flocculonodular
lobe.
A deep horizontal fissure that is found
along the margin of the cerebellum
separates the superior from the
inferior surfaces; it is of no
morphologic or functional significance

7. Structure of the Cerebellum
The cerebellum is composed of
an outer covering of gray matter
called the cortex and inner white
matter.

8. A section made through the cerebellum parallel
with the median plane divides the folia at right
angles, and the cut surface has a branched
appearance, called the arbor vitae.

9. The gray matter of the
cortex throughout its
extent may be divided into
three layers:
(1) an external layer, the
molecular layer
(2) a middle layer, the
Purkinje cell layer
(3) an internal layer, the
granular layer .

11. Functional Areas of the Cerebellar Cortex
Clinically it is possible to divide up the cerebellar cortex
into three functional areas.
1.The cortex of the vermis influences the movements of
the long axis of the body, namely, the neck, the
shoulders, the thorax, the abdomen, and the hips.
2.Immediately lateral to the vermis is a so-called
intermediate zone of the cerebellar hemisphere. This
area has been shown to control the muscles of the
distal parts of the limbs, especially the hands and feet.
3.The lateral zone of each cerebellar hemisphere
appears to be concerned with the planning of sequential
movements of the entire body and is involved with the
conscious assessment of movement errors.

12. Intracerebellar Nuclei
Four masses of gray matter are embedded in the white
matter of the cerebellum on each side of the midline.
From lateral to medial, these nuclei are the dentate, the
emboliform, the globose, and the fastigial.

13. White Matter
There is a small amount of white matter in
the vermis; it closely resembles the trunk
and branches of a tree and thus is termed
the arbor vitae . There is a large amount of
white matter in each cerebellar
hemisphere.
The white matter is made up of three
groups of fibers:
(1) intrinsic,
(2) afferent,
(3) efferent.

14. Cerebellar Peduncles
The cerebellum is linked to
other parts of the central nervous
system by numerous efferent and
afferent fibers that are grouped
together on each side into three
large bundles, or peduncles.
 The superior cerebellar
peduncles connect the cerebellum
to the midbrain,
 the middle cerebellar
peduncles connect the cerebellum
to the pons, and
the inferior cerebellar peduncles
connect the cerebellum to the
medulla oblongata.

17. CEREBELLAR FUNCTIONS
 The cerebellum has several main functions:
 coordinating skilled voluntary movements by
influencing muscle activity,
 controlling equilibrium and muscle tone through
connections with the vestibular system and the
spinal cord.
 There is a somatotopic organization of body parts
within the cerebellar cortex.
 In addition, the cerebellum receives collateral input
from the sensory and special sensory systems.

18. Each cerebellar hemisphere is connected by
nervous pathways principally with the same
side of the body; thus, a lesion in one
cerebellar hemisphere gives rise to signs
and symptoms that are limited to the same
side of the body.

19. Diagnosis of Cerebellar disorders
The main clinical features of cerebellar disorders include
incoordination, imbalance, and troubles with stabilizing eye
movements.
There are two distinguishable cerebellar syndromes –
1. midline and
2.hemispheric.
1.Midline cerebellar syndromes are characterized by
imbalance.
Persons are unsteady, they are unable to stand in with eyes
open or closed, and are unable to well perform tandem gait.
trunkal ataxia .
"titubation" or a bobbing motion of the head or trunk.
also often affect eye movements.
 There may be nystagmus, ocular dysmetria.

20. Hemispheric cerebellar syndromes are characterized by
incoordination of the limbs.
There may be decomposition of movement, dysmetria, and
rebound.
 Dysdiadochokinesis is the irregular performance of rapid
alternating movements.
Intention tremors may be present on an attempt to touch an
object.
A kinetic tremor may be present in motion.
The finger-to-nose and heel-to-knee tests are classic tests of
hemispheric cerebellar dysfunction.

21. THANKS