| 单词 | pyramidal tract |
| 释义 | > as lemmaspyramidal tract pyramidal tract n. Anatomy a major bundle of nerve fibres connecting motor areas of the cerebral cortex with the lower motor neurons of the spinal cord, and forming the pyramid on the ventral surface of the medulla oblongata. ΚΠ 1857 W. S. Kirkes Man. Physiol. 339 The restiform bodies are separated from each other posteriorly by two narrow columns, the posterior pyramids, or posterior pyramidal tracts, one on each side of the posterior fissure. 1945 Penguin New Biol. 1 57 In mammals there is a direct pathway of communication, the pyramidal tract, from neurons of the cerebral hemisphere to the motor neurons of the spinal cord. 1990 Lancet 8 Sept. 602/1 Tremor and pyramidal tract signs, particularly brisk reflexes with or without extensor plantar responses, are found in many patients. pyramidal tract spec. (a) Anatomy. The whole extent of an organ or system of organs, as the alimentary or digestive tract, or a continuous longitudinal structure, such as one strand or division of a nerve-cord; esp. applied to particular regions of the brain or spinal cord, as the olfactory tract, optic tract, pyramidal tract, etc. Cf. fibre tract n. at fibre n. Compounds 2. (b) Ornithology. A feathered area of the skin of a bird (= pteryla n.), as distinguished from a featherless space.extracted from tractn.3< as lemmas |
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