1、cerebellum(小脑),cerebellum,Location: The cerebellum lies behind the pons and medulla oblongata in post. cranial fossa,cerebellum,External features:The cerebellum consists of two cerebellar hemispheres and the vermis小脑蚓 . The tonsils of cerebellum are two elevated masses on the inferior surface of the
2、 hemispheral portion just behind the flocculonodular lobe and nearby the foramen magnum. Vermis of cerebellum consists of uvula (蚓垂) and pyramid of vermis, nodule etc.,cerebellum,Lobes of cerebellumThe cerebellum can also be divided by its connections and phylogenetically(种系发生) into such three porti
3、ons : the flocculonodular lobe (the vestibulocerebellum or archicerebellum),the anterior lobe (the spinocerebellum or paleocerebellum ),the posterior lobe (cerebrocerebellum or neocerebellum),cerebellum,Grey matter: cortex and four pairs of central nuclei embedded in the medullary center. white matt
4、er: medullary,I The cerebellar cortex,Three layers in histologic sections: molecular layer, the layer of purkinje cells, the granule cell layer.,I The cerebellar cortex,two types of afferent fibres to the cortex:Mossy fibres terminate in synaptic contact with granule cells of the innermost layer cli
5、mbing fibres enter the molecular layer and wind among the dendrites of purkinje cells .The only fibres leaving the cortex are axons of purkinje cells .These fibres terminate in central nuclei of the cerebellum ,with the exception of some fibres from the cortex of the flocculonodular lobe that procee
6、d to the brain stem.,II The cerebellar nuclei,Four pairs of nuclei fastigial nucleusglobose nucleusemboliform nucleusdentate nucleus,II The cerebellar nuclei,The dentate nucleus is the largest one and lies most laterally .It receives the fibres from the cerebellar cortex .The fibres arise in the den
7、tate nucleus as the bulk of the superior cerebellar peduncle to reach the red nucleus and the thalamus .,小脑上脚交叉,III The white matter,The projection fibres are three large bundles or peduncles1)The inferior cerebellar peduncle (the restiform body 绳状体) 2)The middle cerebellar peduncle (brachium pontis
8、 脑桥臂) 3)The superior cerebellar peduncle (brachium conjunctivum 结合臂 ),III The white matter,1)The inferior cerebellar peduncle It is composed of the fibres from the inferior olivary complex, the dorsal spinocerebellar tract ,the reticular formation in the medulla, the vestibular nuclei and vestibular
9、 nerve .also contains the efferent fibres proceed from the flocculonodular lobe and fastigial nucleus to the vestibular nuclei and the reticular formation in the medulla and pons,III The white matter,2)The middle cerebellar peduncleIt continues from the dorsolateral region of the pons and is compose
10、d almost exclusively of the corticopontocerebellar fibres.,III The white matter,3)The superior cerebellar peduncle It connects the cerebellum with the midbrain. It consists mainly of the efferent fibres from the globose, emboliform, and dentate nuclei (e.g., the cerebellorubral tract and the dentato
11、thalamic tract ). It also contains the afferent fibres, such as the anterior (ventral ) spinocerebellar tract.,IV The function of cerebellum,The vestibulocerebellum archicerebellum is concerned with the maintenance of equilibrium; The spinocerebellum paleocerebellum influences muscle tonus and synergy of muscles during stereotyped movements such as those of postural changes and locomotion ; The pontocerebellum neocerebellum ensures the coordination of muscles for accuracy of nonstereotyped movements . The three divisions overlap to some extent in both the cortex and the central nuclei .,
