Genesis and Significance of Palmar and Digital Creases

Our studies of skin creases in the early developing hand and in a variety of malformed hands show that these creases, which develop between 7 and 14 weeks of fetal life, are secondard to the early flexion planes in the developing hand. Thus with lack of development or flexion of a digital joint no underlying digital crease was found of a digital joint no underlying digital crease was found; and with lack of formations or oppositional function of the thumb there was no thenar palmar crease. The normal distal palmar sloping crease was found to be related to the sloping flexional plane of the 3rd, 4th, and 5th metacarpal-phalangeal joints and the usual mid-palmar crease represents the plane of skin folding between the sloping distal crease and the thenar crease. The occurrence of a single horizontal palmar crease, the simian crease, was found by roentogenographic studies to be related to a diminished slope of the 3rd, 4th, and 5th metacarpal-phalangeal joints such that only a single early horizontal plane of flexion existed in the skin of the upper palm. Thus hand creases provide a record of the early flexional planes of function in the developing hand and any crease abnormality should always be interpreted as an indication of a more primary defeat in form and/ or function of the early developing hand.