A primitive in the Greek. In anatomy, it imports a knot in which nerves from different sources are intimately mixed. Where two nerves join together, there is generally a ganglion, or plexus; as may be seen at the beginning of all the nerves of the medulla spinalis, and in many other parts of the body. See Plexus, and Cerebrum.

In surgery, it is a moveable tumour formed on the tendons; generally about the carpus; but always near the skin, and not attended with any uneasiness. Ganglions are supposed to be formed of lymph, secreted within the vaginae of tendons, differing in their form and consistence, though they never suppurate. Mr. Sharp reckons these tumours among those encysted ones called meliccris. Dr. Cullen ranks it as a genus in the class locates, and order lumores, and defines it, a hard moveable extuberation, fixed upon a tendon.

Mr. Sharp assures us, that he hath frequently succeeded by making an incision through their whole length, at the same time dividing the ligament of the wrist, and afterwards dressing as in wounds in general. Mr. Warner gives two instances of his successfully extirpating them: he observes, that the objection from danger of wounding the subjacent tendon or ligament is of little importance, since these parts can be generally avoided; and the accident occurs daily in wounds without danger. He recommends the cutting away part of the cyst, and then destroying the rest by digestion. A seton passed through them is a safe and easy cure. See

Sharp's Operations in Surgery, in the chapter on encysted tumours. Warner's Cases in Surgery. Heister's Surgery. Bell's Surgery, vol. v. p. 476.