THE CEREBELLUM
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!!!