decussate

adj

1. Crossed; intersected; resembling a letter X.
2. Having anatomical structures or markings crossing each other, typically in an X shape or at right angles.
3. Having opposite leaves arranged alternately at right angles.

   “Juniperites, ju-ne-per-i′tis, s[ubstantive]. A genus of fossil plants, in which the branches are ranged irregularly; leaves short, obtuse, inserted by a broad base, opposite, decussate, and arranged in four rows.”

4. (rhetoric)Consisting of two rising and two falling clauses, placed in alternate opposition to each other.

   “a decussated period”

verb

1. To form an X or to cross or intersect.

   “The two trochlears decussate in the anterior medullary velum.”