Histomorphologic Approach for the Modiolus With Reference to Reconstructive and Aesthetic Surgery

Abstract

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.

Anatomical and radiological evaluation of modiolus anguli oris in facial anatomy

“…The increased knowledge of the surgeon regarding modiolus and its relations will provide benefit not only for the procedures such as face lifting and botulinum toxin injection, but also for the surgeries of facial paralysis and trauma patients. A better comprehension of surgical anatomy and understanding of how facial anatomical relationships change with aging will lead to advances in plastic and reconstructive surgery [2,3,7,10,14,15].…”

“…Modiolus is a dense, mobile fibromuscular structure that is found on the lateral border of the corner of the mouth [1][2][3]. It is composed of engaging muscle fibers around the mouth.…”

“…The fibers attaching to modiolus form spirals and then separate into two or more fiber bundles, each bundle coursing in separate ways. It extends between the orbicularis oris muscle and labial tractor muscles ending at the angle of the mouth [2,3] (Figure 1). In general, nine muscles attach to modiolus: Buccinator, risorius, orbicularis oris, depressor anguli oris, depressor labii inferioris, zygomaticus major, platysma pars modiolaris, levator anguli oris and mentalis.…”

“…Patients with a prominent nasolabial fold, which is considered one of the principle landmarks of lower face aging, have weak trophic modioli [2,5]. In the literature, there are microscopic studies examining its histo-morphological structure [2,5], and macroscopic cadaveric studies indicating the relationship of modiolus with the vessels and neighboring expression muscles [4]. Location of the modiolus was also studied in living individuals by palpation [6].…”

“…Modiolus has a key role in the formation of nasolabial fold, which is why it is particularly important in aesthetic and reconstructive surgery [2]. The modiolus can be regarded as an angular corner stone because the shape of the nasolabial fold is in direct relation with it [7].…”