Histomorphologic approach for the modiolus with reference to reconstructive and aesthetic surgery.

The modiolus is strongly associated with facial expression, beauty, and aging, and so it is often viewed as the main facial landmark, both functionally and aesthetically. This study examined the modiolus and the surrounding structures histomorphologically with the aim of providing useful information for reconstructive and aesthetic surgery. Nineteen embalmed cadavers (38 hemifaces; 8 males and 11 females; mean age at death, 66.9 years) were examined in this study. For macroscopic observations, the modiolus and facial artery in the perioral region of 28 hemifaces were revealed by meticulous dissection. The modiolus and its surrounding structures were then prepared from 12 hemifaces for routine histology and stained with hematoxylin-eosin and Masson trichrome. A tendinous tissue nodule in the modiolus was found in 21.4% of cases (ie, 6 hemifaces). The facial artery passed approximately 1 mm lateral to the lateral border of the modiolus. In the central region of modiolus, which was an area of convergence of muscle fibers, the tendinous structure appeared as dense irregular collagenous connective tissue. Particularly in the middle layer between the skin and the oral mucosa, it appeared as a dense, compact, and prominent shape horizontally. The finding of the existence of a tendinous structure in the central region of the modiolus, which could act as an anchor for the converging facial muscles, is expected to provide critical information in the field of facial plastic surgery.