A term denoting the situation in which the boundary between the fourth and fifth postcingular homologues (IV/V) appears to be significantly distal in location relative to the boundary between the third and fourth precingular homologues (4/5), as if the hyposome has been rotated distally with regard to the episome. Such configurations are termed sinistrally contorted. The present use of the term sinistral is analogous to its use in structural geology in describing relative movements along faults. See also dextral torsion and neutral torsion. Refer to Text-Figure 83A.