Palmar crease

A hand showing a single transverse palmar crease, also known as a simian line.

A palmar crease is a line that appears on the palm of the hand. These creases are formed during the development of the fetus and are present at birth. The pattern and number of palmar creases can vary among individuals and can sometimes be associated with certain medical conditions.

Types of Palmar Creases

There are typically three main palmar creases on a human hand:

• The distal transverse palmar crease, also known as the "head line," runs across the upper part of the palm.
• The proximal transverse palmar crease, also known as the "heart line," runs below the distal crease.
• The radial longitudinal crease, also known as the "life line," curves around the base of the thumb.

Single Transverse Palmar Crease

A single transverse palmar crease, commonly referred to as a "simian line," is a single line that runs across the palm, merging the distal and proximal transverse creases into one. This feature is present in approximately 1% of the general population.

Medical Significance

The presence of a single transverse palmar crease can be a normal variant, but it is also associated with certain genetic disorders and syndromes. For example, it is more commonly observed in individuals with Down syndrome, Fetal alcohol syndrome, and other chromosomal abnormalities.

Development

Palmar creases develop during the 12th week of gestation as the fetus moves its hands. The creases are formed by the flexion of the hand and are influenced by genetic and environmental factors. Once formed, the pattern of palmar creases remains unchanged throughout a person's life.

Related Pages

• Dermatoglyphics
• Down syndrome
• Fetal alcohol syndrome
• Genetic disorders