This article describes the identification of the first known specimen in which an articular origin for an intraneural cyst was recognized. Prompted by early citations in the 20th century of a valuable 1904 tibial intraneural ganglion housed at St. Bartholomew's Hospital in London, we traveled there to research it. We fortuitously discovered a citation to an earlier joint-related specimen, one that had not previously been referenced correctly in subsequent publications on intraneural cysts for more than a century. The original anatomic description dating to 1884, summarized in 3 lines in a museum catalog, was attributed to T. Swinford Edwards. This cadaveric specimen affected the deep branch of the ulnar nerve and arose from a carpal joint. Additional information was provided in a Transactions in 1884. An original drawing of the specimen was published in a textbook written in 1889 by Anthony Bowlby, a former curator, both of which credited F. (Frederick) Swinford Edwards, a demonstrator in anatomy and surgery at St. Bartholomew's. Unfortunately, the specimen could not be located and is presumed lost. To establish this specimen as the first known example of a joint-related intraneural cyst, we completed a review of >400 other cases and confirmed this statement. The first observation of an articular origin for an intraneural cyst, made by 2 eminent surgeons, has not been properly acknowledged. Considered with a modern perspective, this historical case solidifies the articular (synovial) origin for these unusual intraneural cysts, a finding that has important treatment implications.