The extended fibers of the alar part of the nasalis connect to the levator labii superioris, zygomaticus minor, and skin adjacent to the nasal ala.

Purpose: This study aimed to elucidate the positions of the extended fibers of the alar part of the nasalis (Na), and their connections to the levator labii superioris (LLS), zygomaticus minor (Zmi), and adjacent skin near the nasal ala.

Methods: The extended fibers of the Na were investigated in 54 specimens obtained from 27 embalmed adult South Korean cadavers.

Results: In 51.9% of the specimens, some fibers of the Na extended over the alar facial crease, intermingling or blending with the LLS or Zmi, and attached to the skin lateral to the nasal ala. The quantity and distribution of these extended fibers varied: some fibers of the Na extended and intermingled or blended with the LLS in 25.9%, while another 25.9% exhibited the Na extending in a distinctive fan shape with longer fibers, and combining with both the LLS and Zmi. However, the Na had no extended fibers that reached the LLS, Zmi, or skin near the nasal ala in 48.1%.

Conclusion: Contraction of the Na and its extended fibers can influence the nasal ala and also the laterally located skin and muscles, directing them inferomedially toward the incisive fossa of the maxilla, which is the origin of the nasalis. These insights offer a deeper understanding of the role and actions of facial muscles in facial expression. They will be instrumental in the comprehension and analysis of nose and mouth movements, and in conducting electromyographic analyses in this region.