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  • Title: Nerve fibre organisation in the human optic nerve and chiasm: what do we really know?
    Author: Pawar PR, Booth J, Neely A, McIlwaine G, Lueck CJ.
    Journal: Eye (Lond); 2024 Aug; 38(12):2457-2471. PubMed ID: 38849598.
    Abstract:
    A recent anatomical study of the human optic chiasm cast doubt on the widespread assumption that nerve fibres travelling in the human optic nerve and chiasm are arranged retinotopically. Accordingly, a scoping literature review was performed to determine what is known about the nerve fibre arrangement in these structures. Meta-analysis suggested that the average number of fibres in each optic nerve was 1.023 million with an inter-individual range of approximately 50% of the mean. Loss of nerve fibres with age (approximately 3,400 fibres/year) could not account for this variability. The review suggested that there might be a retinotopic arrangement of nerve fibres in the orbital portion of the optic nerve but that this arrangement is most likely to be lost posteriorly with a more random distribution of nerve fibres at the chiasm. Limited studies have looked at nerve fibre arrangement in the chiasm. In summary, the chiasm is more 'H-shaped' than 'X-shaped': nerve fibre crossings occur paracentrally with nerves in the centre of the chiasm travelling coronally and in parallel. There is interaction between crossed and uncrossed fibres which are widely distributed. The review supports the non-existence of Wilbrand's knee. Considerable further work is required to provide more precise anatomical information, but this review suggests that the assumed preservation of retinotopy in the human optic nerve and chiasm is probably not correct. 摘要: 最近一项关于人类视交叉的解剖学研究对人视神经和视交叉中的神经纤维是否以视网膜区域定位的方式排列的普遍接受的观点提出了质疑。因此, 我们对文献综述进行了范围界定, 以确定这些结构中神经纤维排列的已知信息。Meta分析表明, 每条视神经中的平均纤维数量为102.3万条, 个体间差异约为平均值的50%。随年龄增长造成神经纤维的丢失(大约3400根/年)不能解释这种可变性。本综述提出, 视神经的眼眶部分可能存在神经纤维的视网膜定位排列, 但随后这种排列方式很有可能在视交叉处随着神经纤维的随机分布而消失。总之, 视交叉更多的是‘H’形而不是‘X’形: 神经纤维交叉出现在中央附近, 视交叉中心的神经沿冠状方向平行行进。广泛分布的交叉纤维和非交叉纤维之间存在相互作用。本综述支持Wilbrand膝不存在的说法。要获得更精确的解剖学信息还需大量的进一步研究, 但本综述提出, 在人类视神经和视交叉中视网膜区域对应的假设可能并不正确。.
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