A histological study of the philtrum.

Area of Science:

• Anatomy
• Histology
• Morphology

Background:

• The philtrum, a distinct anatomical feature of the human upper lip, has a unique morphology that has not been fully explained.
• Previous understanding lacked detailed histological data on the philtrum's structure.

Purpose of the Study:

• To elucidate the histological basis of the philtrum's unique configuration.
• To propose a new definition of the philtrum based on histological findings.

Main Methods:

• Histological examination of human fetal, operative, and cadaveric upper lip specimens.
• Transverse sectioning and staining techniques to visualize muscle, connective tissue, and elastic fibers.

Main Results:

• No specific connective tissue condensation was found to form the central philtral groove.
• The orbicularis oris muscle's insertion pattern into the philtral skin is a key finding.
• Muscle fibers decussate in the midline, with extensions inserting into the dermis of the philtral groove and ridges.

Conclusions:

• The dynamic role of the orbicularis oris muscle is crucial in shaping the philtrum.
• A revised definition of the philtrum is proposed, integrating new histological insights.