The Human Design bodygraph has nine centres where the chakra scheme most often cited in modern Western usage has seven. The Spleen is one of the two additions.
No classical original
The Head, Ajna, Throat, Heart, Sacral, Solar Plexus and Root all occupy positions that a classical centre occupies, whatever the differences in what each scheme says about them. The Spleen does not. Neither does the G or Identity centre. Both were introduced with the system in 1987.
Where the name comes from
The organ has a long history in humoral medicine and in several traditional medical systems, so a reader meeting the word may reasonably expect a link to one of them. Human Design's use of the name is its own, and this atlas does not assert a derivation it cannot establish.
Why the additions matter
Two centres with no source counterpart mean the bodygraph cannot be checked against the scheme it adapts. Whatever the system says about this centre rests on its own authority, published by Ra Uru Hu in 1987, and on nothing older.
The other side
The sevenfold chakra scheme is itself a modern popular settlement of a tradition that described varying numbers of centres. The comparison here is between a 1987 construction and that settlement, not between a new system and an unchanging original.
Sources Rainbow Body: A History of the Western Chakra System from Blavatsky to BrennanKurt Leland with The Human Design SystemRa Uru Hu (Alan Robert Krakower)