Decussation

Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (decussis), from Latin decem 'ten' and as 'as').

Similarly, the anatomical term chiasma is named after the Greek uppercase 'Χ' (chi).

Examples include: The origin of the contralateral organization, the optic chiasm and the major decussations on the nervous system of vertebrates has been a long standing puzzle to scientists.

[2] The visual map theory of Ramón y Cajal has long been popular[3][4] but has been criticized for its logical inconsistence.

[5] More recently, it has been proposed that the decussations are caused by an axial twist by which the anterior head, along with the forebrain, is turned by 180° with respect to the rest of the body.

Section of the medulla oblongata at the level of the decussation of the pyramids
Decussate phyllotaxis of Crassula rupestris
In this "true bug", Dysdercus decussatus , in the family Pyrrhocoridae , the specific epithet refers to the bandolier -like markings on the back.