Revisiting the anatomy of myrtiformis muscle.

Abstract

The nasal base muscles are of great functional importance in health and disease. Particularly, the one lacking terminological consensus, but often termed as myrtiformis muscle, which has been mostly omitted by anatomists may have significance for rhinoplasty. The purpose of the current study was to re-examine the anatomical features of myrtiformis muscle. Conducted on 40 sides of 20 formalin-fixed amputated heads, we followed a dissection routine to fully expose the origin and insertion sites of the nasal base muscles. We measured the respective morphometric via digital caliper. Based on the number of bellies and their muscular attachment sites, we described an anatomical classification that consists of three different types of MM which had a single and broad origin. We classified the double-bellied muscle as Type 1 occurred in 10% (4/40), whereas the single-bellied ones as Types 2 and 3, occurred in 80% (32/40) and 10% (4/40), respectively. Measured distance between the medial margin of myrtiformis muscle origin and midline passing through the anterior nasal spine did not differ between any statistical comparisons (P > 0.05). We revisited the muscle which was at some occasions termed as myrtiformis muscle, depressor septi nasi or depressor alae nasi muscles. Considering that there are differential forms of the muscle with the same muscular origin but bearing single or double bellies and/or different insertion sites, our classification may overcome possible terminological confusion by ensuring single muscle term with easily distinguishable morphological types. We invite anatomists to enlarge the data set and comment on our classification, and surgeons to conduct prospective examinations to add deeper insight regarding the functional importance of anatomical classifications by correlating pre vs post-operative functional differences.