The Cerebellum 小 脑

Position: lies above and behind the medulla oblongata and pons; occupies posterior cranial fossa Cerebellum

External features Three peduncles 三对脚 Inferior cerebellar peduncle 小脑下脚 connect with medulla and spinal cord, contain both afferent and efferent fibers

External features Three peduncles 三对脚 Middle cerebellar peduncle 小脑中脚 connect with pons, contain afferent fibers Superior cerebellar peduncle小脑上脚 connect with midbrain, contain mostly efferent fibers

External features Tonsil of cerebellum 小脑扁桃体: two elevated masses on inferior surface of hemisphere, just nearby foramen magnum

Lobes of cerebellum Two deep fissures Primary fissure 原裂 Posterolateral fissure 后外侧裂 Three lobs 1. Flocculonodular lobe绒球小结叶: flocculus 绒球 and nodule 小结 2. Anterior lobe 3. Posterior lobe corpus of cerebellar 小脑体

Lobes Anterior lobe corpus of Cerebellum 小脑体 Primary fissure Posterior lobe nodule 小结 Flocculus 绒球 Flocculonodular lobe 绒球小结叶 Posterolateral fissure

Ⅱ. Internal structures Gray matter Cerebellar cortex 小脑皮质 Cerebellar nuclei 小脑核 Dentate nucleus 齿状核 Fastigial nucleus 顶核 Interposed nuclei 中间核 Emboliform nucleus 拴状核 Globose nucleus 球状核

Ⅱ. Internal structures White matter— medullary center小脑髓体 Cerebellar cortex Fastigial nucleus Globose nucleus Dentate nucleus Emboliform nucleus medullary center

Three functional divisions Spinocerebellum 脊髓小脑( paleocerebellum 旧小脑) : vermis and intermediate zone Cerebrocerebellum 大脑小脑(neocerebellum 新小脑): lateral zone Vestibulocerebellum 前庭小脑 ( archicerebellum原小脑): Flocculonodular lobe and vestibular nuclei vermis intermediate zone lateral zone Flocculonodular lobe

Middle cerebellar peduncle 小脑中脚 Ⅲ. Connections and peduncles of cerebellum Middle cerebellar peduncle 小脑中脚 is composed of fibres which arises in the opposite side of the pontine nuclei and pass to the erebellum, transmit impulses which reach the the pons from the cerebral cortex.

inferior cerebellar peduncle 小脑下脚 Ⅲ. Connections and peduncles of cerebellum inferior cerebellar peduncle 小脑下脚 This peduncle consists mainly of afferent fibres to the cerebellum，inlude posterior spinocerebellar tract； the fibers from the inferior olivary nucleus, the fibers from vestibular nuclei and nerve. It also transmits efferent fibres to the medulla oblongata.

superior cerebellar peduncle 小脑上脚 Ⅲ. Connections and peduncles of cerebellum superior cerebellar peduncle 小脑上脚 This is the principal efferent pathway from the cerebellum, its fibres arises mainly from the dentate nucleus齿状核, and passes anterosuperiorly to the opposite thalamus丘脑 and red nucleus of the midbrain.

IV. Connections and function of cerebellum Vestibulocerebellum 前庭小脑 Afferents fibers 传入纤维: receive input from vestibular nuclei and vestibular n.. Efferents fibers 传出纤维: to the vestibular nucleus → vestibulospinal tract → anterior horn.of spinal cord. → medial longitudinal fasciculus 内侧纵束→ motor nuclei asociated with movement of eyeball。 Function: involved in eyeball movements and maintain the balance of the body

IV. Connections and function of cerebellum Spinocerebellum 脊髓小脑 Afferent fibers: receive somatic sensory information via spinocerebellar tracts. Efferent fibers: to the fastigial nucleus顶核→ vestibular nuclei → vestibulospinal tract → motor neurons of anterior horn

IV. Connections and function of cerebellum Spinocerebellum 脊髓小脑 Efferent fibers: to the interposed nuclei中间核 → ① contralateral red nucleus → rubrospinal tract →motor neurons of anterior horn of spinal cord ② contralateral thalamus对侧丘脑→cerebral cortex大脑皮质

IV. Connections and function of cerebellum Spinocerebellum Function: play an important role in control of muscle tone and coordination of muscle movement on the same side of the body

IV. Connections and function of cerebellum Cerebrocerebellum Afferents: receives input from the cerebral cortex via the pontine nuclei middle cerebellar peduncle Efferents: to dentate nucleus 齿状核→ contralateral thalamus → primary motor cortex → corticospinal tract → motor neurons of anterior horn Function: coordination of muscle movement of limbs.