Flexor digitorum sublimis spiral. Flexor digitorum sublimis separates just distal to level of metacarpophalangeal joint with finger in extension. It winds around profundus tendon to chiasma of Camper, where it decussates to insert in middle phalanx. Superficial portion of proximal sublimis tendon becomes deep at level of chiasma of Camper. If laceration is sustained in sublimis at midpoint of this spiral arrangement of both slips, proximal and distal ends rotate through 90 degrees, but in different directions. An unwary surgeon would be presented with two ends that do match, that appear to lie in good relationship, and that can be so sutured. If this is done, channel for profundus tendon is obliterated. If error is not noted and corrected, effect would be to block excursion of tendon and eliminate satisfactory motion.