THE CEREBELLUM

INTRODUCTION

• Largest part of the hindbrain. • Situated in the posterior cranial

fossa behind the pons and medulla.

• It is an infratentorial structure.

RELATIONS OF CEREBELLUM

EXTERNAL FEATURES

• Two cerebellar hemispheres .• Median vermis.• Two surfaces ----superior and inferior• Anterior and posterior cerebellar notches• Vallecula separating the right and left

hemispheres.• 3 fissures…fissura prima,horizontal fissure and

posterolateral fissure • 3 lobes in each hemisphere .. anterior , posterior

and flocculonodular.

EXTERNAL FEATURES

FISSURES AND LOBES

MORPHOLOGICAL AND FUNCTIONAL DIVISIONS

GREY MATTER OF THE CEREBELLUM

• Consists of the cortex and the nuclei.

• 4 pairs of nuclei…n.dentatus n.emboliformis,n.globosus,and n.fastigii (lateral-medial…Don’t Eat Greasy Food)

Horizontal section showing grey matter

Internal structures

Cerebellar cortex

Dentate nucleus

Fastigial nucleus

Globose nucleus

Emboliform nucleus

medullary center

CONNECTIONS• Fibres are grouped to form 3

peduncles ;superior ,middle and inferior.

• Connect the cerebellum to midbrain ,pons and medulla.

• Middle and inferior are afferent

• Superior is efferent in nature.

Peduncles of the cerebellum

CONSTITUENTS OF THE PEDUNCLES

• SUPERIOR PEDUNCLE :

Afferent tracts:

ant. spinocerebellar Tectocerebellar

dentatoolivary

fastigoreticular

Efferent tracts:

cerebellorubral

dentatothalamic

MIDDLE PEDUNCLE

• mainly afferent: pontocerebellar

• Largest of the 3 peduncles.

INFERIOR PEDUNCLE:

Afferent tracts post.spinocerebellar cuneocerebellar olivocerebellar parolivocerebellar reticulocerebellar vestibulocerebellar ant.ext. arcuate fibres Stria medullaris trigeminocerebellar

• Efferent tracts cerebellovestibular cerebelloolivary cerebelloreticular

Blood supply of cerebellum

• Superior cerebellar A.• Ant.inf. Cerebellar A.• Post.inf.Cerebellar A.

The first two are branches of the Basilar artery ,while the last is a branch of the Vertebral A.

Functions of the cerebellum

• Coordination of voluntary movements …….dysfunction causes incoordination of movements.

• Control of tone,posture,and equilibrium…..

lesions will cause hypotonia and disturbances of equilibrium.

• Cerebellar syndrome : S/S are: muscular hypotonia intention tremors adiodochokinesia nystagmus ataxic gait scanning speech

AND FINALLY….…….

THE END!!!