Nerve tract

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Among neural pathway a line structure is bundled nerve fibers understood that neuroanatomically in the peripheral nervous system and (PNS) as a nerve or nerve and in the central nervous system and (CNS) as a web or tract is referred to.

These more or less closed lines bundle nerve fibers ( Latin fibrae ) or nerve fascicles ( fasciculi ), which pull together over a greater distance; often these have a spatially similar origin or a similar goal or both. For example, the spinothalamic tract in the CNS carries nerve fibers that originate from the spinal cord and end in the thalamus and are named after their place of origin and destination. The central tracts are assigned to the white matter of the brain or spinal cord and usually connect core areas that belong to the gray matter . In addition to tracts , other terms such as fibrae, fasciculus, funiculus, lemniscus, stria, commissura or decussatio are used for individual (nerve) pathways in the CNS .

Critical onomatology

Schematic overview of the visual path.
Sometimes the branches to deeper centers than those of the primary cerebral cortex are tacitly omitted in the representation of long tracts , as here in the picture the connections to the midbrain and diencephalon. The present representation is often accepted as the actual visual path .

According to the anatomical onomatology by Hermann Triepel (1871–1935), Josef Hyrtl (1810–1894) already dealt with the term tractus (Latin for “the train”, “the elongated organ”) in detail. This term is derived from the Latin trahere ' to pull'. According to Ludwik Fleck (1896–1961), cognitive criteria are influenced by historical and social factors. When asked whether the concept of “train” was also anatomically influenced by technical development in the sense of a machine paradigm, one should refer to the criticism of the concept of nervous centers or localization in neurology. In neuroanatomy, even long railways cannot be compared with express trains or as long-distance connections between origin and destination. Furthermore, also notes that the pathways of the brain and the spinal cord never run as completely closed systems. They not only run from the receptor to the center or from center to center, as the name of the pathway usually expresses. Rather, many fibers always shear out of the long afferent tracts, for example, and come into contact with the reflex apparatus. It is therefore important to also observe the level scheme of the stimulus response . For example, the central visual pathway does not run as a completely closed path between the retina and the cerebral cortex, but rather divides into different paths beforehand ( Radiatio tractus optici ). Of these, only the “pars geniculata” to the corpus geniculatum laterale is to be considered as an actually ascending sensory pathway. The remaining tracts (pars mesencephalica and pars thalamica) are to be regarded as sensitive reflex tracts (for example for accommodation and pupillary reflexes as well as for flight reflexes). The nerve tracts therefore represent a combination of the "express train" and "slow train" system on a common "track".

More examples of neural pathways

Web links

Individual evidence

  1. a b duct . In: Helmut Ferner : Anatomy of the nervous system and the human sensory organs. 2nd Edition. Reinhardt, Munich 1964, p. 66.
  2. ^ Railway . In: Norbert Boss (Ed.): Roche Lexicon Medicine . 2nd Edition. Hoffmann-La Roche AG and Urban & Schwarzenberg, Munich 1987, ISBN 3-541-13191-8 , p. 154, cf. a.
  3. see current Terminologia Anatomica ( TA ), p. 104 .
  4. ^ Hermann Voss , Robert Herrlinger : Taschenbuch der Anatomie. Nervous system, sensory system, skin system, incremental system, Volume III. 12th edition. VEB Gustav-Fischer, Jena 1964; on “Corpus geniculatum” as a true center of vision: p. 68.
  5. tractus (onomatolog.). In: Hermann Triepel : The anatomical names. Their derivation and pronunciation , edited by Robert Herrlinger . 26th edition. Published by JF Bergmann, Munich 1962, p. 75.
  6. ^ Joseph Hyrtl : Onomatologia anatomica . History and criticism of the anatomical language of the present. Vienna 1880.
  7. Peter R. Hofstätter (Ed.): Psychology . The Fischer Lexicon, Fischer-Taschenbuch, Frankfurt a. M. 1972, ISBN 3-436-01159-2 , p. 285.
  8. ^ Hermann Voss , Robert Herrlinger : Taschenbuch der Anatomie. Nervous system, sensory system, skin system, incremental system, Volume III. 12th edition. VEB Gustav-Fischer, Jena 1964; to chap. "The central visual pathway": p. 68.