short notes of cerebellum

1. Dept.of Rachana Sharir
Dr Samadhan M Patil

2. Aim
To study of Cerebellum with special reference to Human
anatomy book (B D Chaurasia - 7 th edition)

3. Introduction
 The cerebellum is the largest part of the hind brain
 Situated in the Posterior cranial fossa behind the pons and medulla
 It is an infratentorial structure that co-ordinates voluntary movements of
the body
 Small in size
 Important functions for maintaining tone, posture, and equilibrium of
the body

4.  Controls the same side of the body Directly or indirectly (ipsilateral
control)
 It does not initiate movement, but it contributes to coordination, precision
and accurate timing
 Cerebellum functions as comparator
 The grey matter is highly folded to accommodate millions of neurones in
a small area, called Arbor vitae

6. Relations
 Anteriorly: Fourth ventricle, Pons and Medulla
 Postero-inferiorly: Squamous occipital bone
 Superiorly: Tentorium cerebelli

8. External features
 Consists of two cerebellar hemispheres, that are united to each other through a
median Vermis
 It has -
Two surfaces: 1) Superior 2) Inferior
Three fissure: 1) Fissura prima 2) Horizontal fissure 3) Postero-lateral fissure
Three lobes: 1) Anterior 2) Middle/Posterior 3) Flocculonodular
Three parts: 1) Archicerebellum 2) Paleocerebellum 3) Neocerebellum
Three functional zones: 1) Median/Vermis 2) Intermediate 3) Lateral

9. Surfaces
The horizontal fissure separates the superior surface from the inferior
surface
1. Superior surface:
Slightly convex
The two hemisphere continuous with each other
2. Inferior surface:
Shows a deep median notch called vallecula
Anterior aspect: wide and deep notch (Pons and Medulla)
Posterior aspect: narrow and deep notch (falx cerebelli)

10. Lobes
1. Anterior lobe:
Lies on the anterior part of the superior surface
Separated from the middle lobe by the fissure prima
2. Middle/Posterior lobe:
Largest of three lobes
Situated on both superior and inferior surfaces
Limited anteriorly by the fissure prima (superior surface) and
posteriorly by the postero-lateral fissure (inferior surface)

11. 3. Flocculonodular lobe:
Smallest lobe
Lies on the inferior surface, in front of the postero-lateral fissure

14. Parts
Sr No Parts of Vermis Subdivision of cerebellar hemispher
1 Lingula -
2 Central lobule Ala
3 Culmen Quadrangular lobule
4 Declive Simple lobule
5 Folium Superior semilunar lobule
6 Tuber Inferior semilunar lobule
7 Pyramid Biventral lobule
8 Uvula Tonsil
9 Nodule Flocculus

16. Functional subdivision
1. Archicerebellum:
It includes of the Flocculonodular lobe and the lingula
Connections: Chiefly Vestibular
Control axial musculature, bilateral movements for locomotion, and equilibrium
2. Paleocerebellum:
It includes Anterior lobe (except lingula), the pyramid and the uvula of the
inferior vermis
Connections: Chiefly spinocerebellar
Controls tone, posture, and crude movement of the limbs

17. 3. Neocerebellum:
Largest part of Cerebellum
It includes Middle/Posterior lobe except the pyramid and uvula of the
inferior Vermis
Concerned with the regulation of fine movements of the body

19. Functional zones
1. Vermis/ Median zone: for trunk and girdle movement
 Control of extensor muscles trunk, neck, shoulder and hip
 Through vestibule spinal and reticulospinal tract
2. Intermediate zone: for hands/feet
 Control of muscles of flexor group via rubrospinal tract
3. Lateral zone: for planning and programming movement
 As per above and coordination muscular activities of distal parts of
limbs
 Through dentate rubrothalamocortical tract, descending Corticospinal
and rubrospinal tracts

21. Internal features
 The structure of Cerebellum is uniform throughout, i.e. is homotypical
 Gray matter consists of the cerebellar cortex and the cerebellar nuclei
 There are four pairs of nuclei: 1) Nucleus fastigii (Flocculonodular lobe) 2)
Nucleus emboliformis (Paleo Cerebellum) 3) Nucleus dentatus (Neo
Cerebellum) 4) Nucleus globosus (Paleo Cerebellum)
 The cortex contains three layers as follows: 1) Molecular layer 2) Intermediate
layer/Purkinje cell layer 3) Inner layer/Granular cell layer

24. Connection of Cerebellum
 The fibres entering or leaving the cerebellum are grouped to form three
peduncles which connect the cerebellum to the midbrain, the pons and
the medulla
 Three peduncle
1. Superior cerebellar peduncle: Connects to Midbrain
2. Middle cerebellar peduncle: Connects to Pons
3. Inferior cerebellar peduncle: Connects to Medulla oblongata

26. Blood supply
 Superior cerebellar artery
 Anterior inferior cerebellar artery
 Posterior inferior cerebellar artery

27. Clinical anatomy
 Truncal Ataxia: lesion of vermis
 Gait Ataxia/Staggering gait: lesion of anterior lobe
 Nystagmus: loss of vermis to labyrinth connections
 Incoordination of voluntary movements of the upper limb: Neocerebellar
lesions
 Defective phonation and articulation: Middle lobe defect
 Cerebellum cognitive affective syndrome: thrombosis of one of
cerebellar artery