A novel division of the nasalis muscle of face with special reference to the elastic fiber-mediated insertion: a cadaveric study.

PURPOSE: The nasalis muscle of face is known to comprise of two divisions: the transverse and alar parts. We aimed to describe the novel or third division of the nasalis with special reference to the specific muscle attachment to elastic fiber-rich tissues. METHODS: The nasalis was histologically examined in 20 elderly cadavers. RESULTS: The third division was seen in all 20 cadavers examined. The muscle fibers arose from (1) submucosal tissues at the mucocutaneous junction between the vestibule and nasal cavity and (2) the greater alar cartilage and it inserted to the subcutaneous tissue of the external skin of the nasal ala. Notably, at the origin, elastic fibers connected the endomysium to the cartilage matrix. Along the lateral course, the third division muscle fibers crossed and interdigitated with the alar part of nasalis. Thus, in contrast to the classically described nasalis, the third division connected between the nasal mucocutaneous junction and external skin. In the subcutaneous tissue, each of the muscle fibers inserted into a lattice comprising of thick collagen fiber bundles and elastic fibers crossing each other at an almost right angle. A site-dependent difference in submucosal and subcutaneous tissues was also demonstrated. CONCLUSION: The elastic fiber-mediated muscle insertion was reported in the middle ear against vibration. The origin or insertion of the third division of nasalis seemed to be specialized possibly for adjusting the working distance when the nasal alar skin is pushed, pinched or bent. It was a proper nasal subcutaneous muscle without bony attachments.