Think of a knot on a smooth line. Somewhere along a cord that should run evenly, material gathers and the line swells into a small round rise. That is the one picture this word keeps: a swelling where something has collected. On a in the wrist, what collects is fluid, and you can see and press the lump. On a nerve, what collects is cell bodies, and the swelling becomes a junction where signals meet before travelling on. From there writers borrow the knot once more, for any place where everything in a city or a trade ties together.
From the word’s history
The source records the word as borrowed from Ancient Greek ganglion, glossed as an encysted tumour on a tendon or aponeurosis.
來源記錄它借自古希臘文 γαγγλίον，而希臘文的解釋是「長在肌腱或腱膜上的囊腫」。也就是說，手腕上那顆包才是這個字最早在講的東西。神經上的那一團細胞為什麼共用同一個名字，來源沒有說明；把它們連在一起的「結」是我們給學習者的教學畫面，不是在主張歷史上的先後。
Wiktionary, "ganglion"
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