14. The Cerebellum.pdf

THE CEREBELLUM DR NADINE RAMPF | PHD [email protected] LECTURE OUTLINE Gross anatomy 04 Cerebellar cortex 06 Intracerebellar nuclei 08 White matter 10 Functional divisions 12 Blood supply 15 02 OBJECTIV...

THE CEREBELLUM DR NADINE RAMPF | PHD [email protected] LECTURE OUTLINE Gross anatomy 04 Cerebellar cortex 06 Intracerebellar nuclei 08 White matter 10 Functional divisions 12 Blood supply 15 02 OBJECTIVES Describe the external features of the cerebellum (lobes, fissures) Describe briefly the internal structure of the cerebellum List the cerebellar nuclei, know their function and main connections Relate the anatomical to the functional subdivisions of the cerebellum Describe the important connections of each subdivision 03 LECTURE OUTLINE Gross anatomy Cerebellar cortex Intracerebellar nuclei White matter Functional divisions Blood supply 04 GROSS ANATOMY Located in the posterior cranial fossa and posterior to the 4th ventricle, pons and medulla Covered superiorly by the tentorium cerebelli Two hemispheres joined by narrow median vermis Connected to the brainstem via superior, middle and inferior cerebellar peduncles 3 lobes 1. Anterior (paleocerebellum) On superior surface Separated from middle lobe by V-shaped primary fissure 2. Middle (neocerebellum) Sometimes called posterior lobe Located between primary and uvulonodular fissures 3. Flocculonodular (archicerebellum) Located posterior to the uvulonodular fissure Horizontal fissure separates superior and inferior surface Composed of outer layer of gray matter (cortex) and core of white matter Intracerebellar nuclei within the white matter 05 LECTURE OUTLINE Gross anatomy Cerebellar cortex Intracerebellar nuclei White matter Functional divisions Blood supply 06 CEREBELLAR CORTEX Folds (folia) lying in the coronal or transverse plane Each fold or folium contains a core of white matter covered superficially by gray matter A section made through the cerebellum parallel with the median plane divides the folia at right angles The cut surface has a branched appearance, called the arbor vitae The gray matter of the cortex throughout its extent has a uniform structure and divided into three layers: Molecular layer (external) Purkinje cell layer (middle) Granular layer (internal) 07 LECTURE OUTLINE Gross anatomy Cerebellar cortex Intracerebellar nuclei White matter Functional divisions Blood supply 08 INTRACEREBELLAR NUCLEI Dentate nucleus Largest of the cerebellar nuclei Has the shape of a crumpled bag with the opening facing medially Interior of the bag is filled with white matter made up of efferent fibers that leave the nucleus through the opening to form a large part of the superior cerebellar peduncle The emboliform Ovoid and situated medial to the dentate nucleus, partially covering its hilus Globose nucleus Consists of one or more rounded cell groups that lie medial to the emboliform nucleus Fastigial nucleus Lies near the midline in the vermis and close to the roof of the fourth ventricle Larger than the globose nucleus The intracerebellar nuclei are composed of large, multipolar neurons with simple branching dendrites The axons form the cerebellar outflow in the superior and inferior cerebellar peduncles 09 LECTURE OUTLINE Gross anatomy Cerebellar cortex Intracerebellar nuclei White matter Functional divisions Blood supply 10  WHITE MATTER Small amount of white matter in the vermis Large amount of white matter in each cerebellar hemisphere Consists of three groups of fibres: Intrinsic Does not leave the cerebellum Connect different regions of the organ Some interconnect folia of cerebellar cortex and vermis on the same side Others connect the two cerebellar hemispheres together Afferent Form greater part of white matter and proceed to cerebellar cortex Enter cerebellum mainly through inferior and middle cerebellar peduncles Efferent Commence as the axons of the Purkinje cells of the cerebellar cortex The great majority of the Purkinje cell axons pass to and synapse with the neurons of the cerebellar nuclei (fastigial, globose, emboliform, and dentate) A few Purkinje cell axons in the flocculonodular lobe and in parts of the vermis bypass the cerebellar nuclei and leave the cerebellum without synapsing Fibres from the dentate, emboliform and globose nuclei leave the cerebellum through the superior cerebellar peduncle Fibres from the fastigial nucleus leave through the inferior cerebellar peduncle 11 LECTURE OUTLINE Gross anatomy Cerebellar cortex Intracerebellar nuclei White matter Functional divisions Blood supply 12 FUNCTIONAL AREAS The cerebellar cortex can be divided into three functional areas The cortex of the vermis Influences the movements of the long axis of the body (i.e. the neck, shoulders, thorax, abdomen, and hips) Intermediate zone Immediately lateral to the vermis Control the muscles of the distal parts of the limbs, especially the hands and feet Lateral zone Concerned with the planning of sequential movements of the entire body Involved with the conscious assessment of movement errors 13 FUNCTIONAL SUBDIVISIONS t st Oldes Newe ARCHICEREBELLUM PALEOCEREBELLUM NEOCEREBELLUM Vestibulocerebellum Spinocerebellum Cerebrocerebellum Part of cerebellum Flocculonodular lobe Vermis and paravermis Rest of cerebellum Nuclei Fastigeal Globose and emboliform Dentate Afferents From vestibular nuclei (through ICP) From spinal cord (dorsal & ventral From pons (through MCP) spinocerebellar tracts through ICP and SCP, respectively) Efferents To vestibular nuclei (through ICP) To red nucleus (through SCP) To red nucleus but mostly to ventral lateral nucleus of thalamus (through SCP) then to motor cortex Function Controls balance Influences posture & muscle tone Coordination of voluntary movements 14 LECTURE OUTLINE Gross anatomy Cerebellar cortex Intracerebellar nuclei White matter Functional divisions Blood supply 15 BLOOD SUPPLY The cerebellum is supplied by branches of the vertebrobasilar system 3 Branches: Superior cerebellar artery Supply superior region of the cerebellum Anterior inferior cerebellar artery Supply anterior and inferior regions of the cerebellum Posterior inferior cerebellar artery Supply the cerebellar nuclei, inferior region and vermis of the cerebellum 16  THANK YOU FOR YOUR ATTENTION Content for this lecture: Chapter 6 | Snell's Clinical Neuroanatomy, 8th Edition