Correction of the Topographic Relationship between the Depressor Septi Nasi and Incisivus Labii Superioris: Application to Cosmetic Surgery on the Lip and Nose.

[BACKGROUND] The depressor septi nasi is a facial muscle with many different descriptions of its anatomy. Therefore, the aim of this study was to clarify the relationship of the depressor septi nasi, incisivus labii superioris, and surrounding structures.

[METHODS] Twenty sides from 10 fresh-frozen cadaveric heads were used in this study. The depressor septi nasi and incisivus labii superioris were dissected intraorally and extraorally, and the relationship with surrounding structures was observed.

[RESULTS] Eighteen of 20 sides had a depressor septi nasi. When present, the depressor septi nasi originated from the orbicularis oris above the central incisor and the medial portion of the inferior part of the incisivus labii superioris and inserted into the base of the medial crus of the major alar cartilage and nasal septum. These three muscles were three-dimensionally fused at the insertion point of the depressor septi nasi. There was no specimen where the depressor septi nasi originated directly from the maxilla. The depressor septi nasi runs obliquely from the nasal septum and the base of the medial crus of the major alar cartilage to the orbicularis oris and inferior part of the incisivus labii superioris.

[CONCLUSION] A better understanding of the depressor septi nasi, incisivus labii superioris, and surrounding structures might be important during various surgical techniques, especially rhinoplasty.