The morphology and origin of the skeletal muscle bundles associated with the human mustache

Abstract

The arrector pili muscle is a smooth muscle bundle that attaches to the bulge region of the hair follicle and extends to its superior attachment in the upper dermis or epidermis. However, the morphology and origin of the muscle associated with the human mustache is different, having a general smooth arrector pili muscle. The purpose of the present study was to identify the morphology of the muscle associated with the human mustache using three-dimensional reconstruction. The skin of the superior part of the upper lip region from human cadavers were fixed, processed using routine histological methods, serially sectioned at a thickness of 10 mu m, and then stained with Masson's trichrome. The serial sections were reconstructed three-dimensionally using 'Reconstruct' software. The present study confirmed skeletal muscle fibers in this area, but they did not attach to the follicle of the human mustache. Although the follicle of the mustache was surrounded with some muscle fibers, they just ran obliquely to the skin surface from the deeper orbicularis oris muscle regardless of the follicle. There was no muscle associated with the human mustache. The voluntary or involuntary mobility of the human mustache has been lost evolutionally forever.