Székely G
Department of Anatomy, University Medical School, Debrecen, Hungary.
Eur J Morphol. 1994 Aug;32(2-4):217-24.
Changes of cranial nerve nuclei are investigated at three crucial points of phylogenesis in frogs, lizards and rats. Profound changes can be observed in the trigeminal and facial motor nuclei parallel to transformation of the primary mandibular joint into the secondary mandibular joint. New muscles appear for mastication and facial expression and they are innervated by new types of neurons. The muscular tongue appears first in tetrapods coinciding with terrestrial life. It can be shown that an entirely new type of neuron develops at the medullospinal junction for the innervation of the intrinsic tongue muscles. These muscles and their neurons are not homologous to somatic muscles and spinal cord neurons. The external eye muscles and their innervation are present from the early craniates through apes in virtually the same pattern of organization. They evolved coincidently with the head and are not homologous to any other structures. It is concluded that if we accept the 'neogenesis' view in head evolution, all contradictions imposed, by the 'segment theory', upon the interpretation and classification of cranial nerve nuclei can be circumvented.
在青蛙、蜥蜴和大鼠进化发育的三个关键节点研究脑神经核的变化。随着原发性下颌关节向继发性下颌关节的转变，可观察到三叉神经和面神经运动核发生了深刻变化。出现了用于咀嚼和面部表情的新肌肉，并且由新型神经元支配。肌肉性舌首先出现在与陆地生活同时期的四足动物中。可以证明，在延髓脊髓交界处发育出一种全新类型的神经元，用于支配舌内肌。这些肌肉及其神经元与躯体肌肉和脊髓神经元不同源。从早期有头动物到猿类，眼外肌及其支配以几乎相同的组织模式存在。它们与头部同时进化，与任何其他结构都不同源。得出的结论是，如果我们在头部进化中接受“新生说”观点，那么“节段理论”在解释和分类脑神经核时所带来的所有矛盾都可以避免。
