Tracts的用法和樣例：
例句
- Neurons are concentrated in clusters with defined nerve tracts leading in and out.
神經元聚集成束，束定義為引進引出的神經束。 - The midbrain nuclei include four motor tracts that send upper motor neuronal axons down the spinal cord to lower motor neurons.
中腦核包括四條運動束，用以傳送上位運動神經元的軸突經脊髓至下運動神經元。
