Cerebellum and Fourth Ventricle Flashcards
Parts of cerebellum
- cerebellar hemispheres connected by vermis
- superior vermis contd. with sup. surface of cerebellum
- inf. vermis more demarcated
Surfaces of cerebellum
- convex superior surface
- inferior surface has deep notch - vallecula
- floor of vallecula formed by inf. vermis
- ant. cerebellar notch has pons, medulla
- post. cerebellar notch has falx cerebelli
Fissures of cerebellum
- Primary: on superior surface
- Horizontal: on lateral and posterior margin. separates superior and inferior surfaces
- Posterolateral: on inf. surface. Separates cerebellum from flocculus
Archicerebellum
- oldest
- flocculonodular lobe + lingula
- Nucleus fastigii
- Maintenance of equilibrium, tone and posture
Paleocerebellum
- Anterior lobe + pyramid + Uvula
- Nucleus globosus, nucleus emboliformis
- Crude mvmts of limbs
Neocerebellum
- Posterior lobe except pyramid, uvula
- Nucleus dentatus
- Skilled voluntary mvmts
Layers of cerebellar cortex
- Outer molecular
- Purkinje cell
- Inner granular
Molecular layer of cerebellum
- mainly dendrites of purkinje cells
- 2 types of nerve cells: basket, stellate
Basket cells: long processes
Stellate cells: short processes
*Both inhibit Purkinje cells
Purkinje cell layer of cerebellum
- flask shaped purkinje cells
- dendrites enter upper molecular layer
- dendrites synapse with basket cells, granule cells, climbing fibres
- axons enter lower granular layer and relay to intracerebellar nuclei (-)
Granule layer of cerebellum
- small granule and large golgi cells
- dendrites of granule cells synapse with mossy fibres
- axons of granule cells enter molecular layer and form parallel fibres by branching into T junction which synapse with Purkinje cells
Intracerebellar nuclei
Lat to Med
- Dentate
- Emboliform
- Globose
- Fastigial
Climbing fibres
- from inf. olivary nucleus
- sends collateral to intracerebellar nucleus
- then makes monosynaptic connection with purkinje cell
- produces Aspartate
Mossy fibres
- all afferents except from inf. olivary nucleus
- synapse with granule cells and Golgi cells
- produce Glutamate
Dentate nucleus
- largest
- nucleus of neocerebellum
- gives dentatorubral and dentatothalamic fibres
Emboliform nucleus
- oval
- nucleus of palaeocerebellum
- gives fibres to red nucleus through sup. cerebellar peduncle
Fastigial nucleus
- Nucleus of archicerebellum
- receives from flocculonodular lobe
- sends fibres to vestibular and reticular nuclei
Afferent fibres in inferior cerebellar peduncle
- Cuneocerebellar: ipsi. accessory cuneate n.
- Olivocerebellar: contra. inf. olivary n.
- Parolivocerebellar: contra. accessory olivary n.
- Reticulocerebellar: reticular n.
- Vestibulocerebellar: vestibular n.
- Posterior spinocerebellar: ipsi. Clarkes column
Efferent fibres of inferior cerebellar peduncle
- Cerebellovestibular: ipsi. flocculonodular lobe
- Cerebelloreticular: fastigial n. to pontine and medullary reticular formation
- Cerebelloolivary
Afferent fibres of middle cerebellar peduncle
- Pontocerebellar
- Reticulocerebellar
- Seratogenic: from raphae n.
NO EFFERENTS
Afferent fibres of superior cerebellar peduncle
- Anterior spinocerebellar tract
- Tectocerebellar
- Trigeminocerebellar
- Ceruleocerebellar: locus ceruleus
- Hypothalamocerebellar
Efferent fibres of superior cerebellar peduncle
- Cerebellorubral
- Dentatorubral/thalamic
- Cerebelloolivary
- Cerebelloreticular
Functions of cerebellum
Comparator function
- Cerebral cortex sends simultaneous signals to cerebellum and LMN for voluntary mvmt
- Cerebellum compares intended and actual mvmt
- If it senses mistakes, it sends signals to cortex to correct mvmt
Therefor, smooth, coordinated mvmt
Arterial supply of cerebellum
- Superior cerebellar
- Anterior inferior cerebellar
- Posterior inferior cerebellar
Cerebellar lesions
- Staggering gait
- Nystagmus
- +ve Romberg sign
PALAEO: - Flail joints
- Pendular knee jerk
- Ataxia
NEO: - Dysmetria (distance)
- Intention tremors
- Dysdiadochokinesia (rapid pronation and supination)
- Scanning speech
- Rebound phenomenon
Lateral recesses of 4th ventricle
- on each side
- reaches upto flocculus
- opens into subarachnoid space as foramen of Luschka
Median dorsal recess of 4th ventricle
- extends into core of cerebellum
- lies cranial to nodule
Lateral dorsal recesses of 4th ventricle
- above inferior medullary velum
- lateral to nodule
Lateral boundaries of 4th ventricle
Inferolaterally: inf. cerebellar peduncle
Superolaterally: sup. cerebellar peduncle
Roof of 4th ventricle
Upper part: sup. medullary velum
Lower part: inf. medullary velum with foramen Magendie
Tela choroidea
- double layer fold of pia mater
- b/w inferior vermis and inf. medullary velum
- dorsal layer lines inf. vernis
- ventral layer contd. with pia mater covering cerebellum
Choroid plexus of 4th ventricle
- b/w 2 layers of tela choroidea
- projects from lower part of roof of 4th ventricle
- from branches of posterior inferior cerebellar A
- T shaped: T limb into foramen of Luschka
Floor of 4th ventricle
- posterior surface of pons, upper part of medulla
- Stria medullaris divides upper and lower parts
- Medial sulcus with medial eminence bounded by sulcus limitans
- sup. and inf. fovea
- locus ceruleus
- facial colliculus
- hypoglossal and vagal triangle
- area postrema
