三、小脑 Third, the cerebellum
（一）位置 (A) Location
小脑位于颅后窝内，延髓和脑桥的后方。 Fossa, located in the medulla and pons rear posterior cerebellum.
（二）外形 (B) the shape
主要有小脑半球、小脑蚓、小脑扁桃体等结构。 There are cerebellar hemispheres, cerebellar vermis, cerebellar tonsil and other structures.
小脑扁桃体：位于小脑的下面，邻近枕骨大孔，当颅内压升高时，可挤向枕骨大孔压迫延髓，形成小脑扁桃体疝，而危及生命。 Tonsillar: Located below the cerebellum, near the foramen magnum, when intracranial pressure can be pressed against the oppression of the foramen magnum medulla form tonsillar herniation, and life-threatening.
（三）内部结构 (C) the internal structure
表面为皮质，深面为髓质，髓质中含小脑核。 Surface of the cortex, the deep surface of the medulla, cerebellar nuclei containing medulla.
（四）功能 (Four) function
1． 1. 维持身体平衡 Maintain body balance
2． 2. 调节肌张力 Regulate muscle tone
3． 3. 协调肌群运动 Coordinated muscle movement
小脑功能 Cerebellar function
小脑本领强 Strong ability cerebellum
平衡肌紧张 Balance muscle tension
协调肌运动 Coordinated muscle movement
千万莫损伤 Do they damage
（五）第四脑室 (E) the fourth ventricle
1． 1. 位置 Location
是位于延髓、脑桥、和小脑之间的腔隙。 Is located in the medulla oblongata, lacunar pons, and cerebellum between. 底为菱形窝，顶伸入小脑内。 Bottom of rhomboid fossa, top stretching cerebellum.
2． 2. 沟通 Communication
下通脊髓中央管，上通中脑水管，借第四脑室正中孔和外侧孔与蛛网膜下腔相通。 Under the central canal of the spinal cord pass on through the cerebral aqueduct, by the middle of the fourth ventricle and the lateral bore hole communicates with the subarachnoid space.
