| Summary: | Background. Human head and neck muscles have a special morphology and fiber type composition, different from limb and trunk muscles. Recent studies show that human muscles in palate differ from limb by having a unique cytoarchitecture. A subgroup of muscle fibers lacked cytoskeletal protein desmin and C-terminus of dystrophin molecule. These proteins are considered ubiquitous in human muscles and their absence are only reported in genetic muscular disorders. Aim. In this study, we intend to explore if other head and neck muscles have muscle fibers with absence of the cytoskeletal protein desmin. Methods. Twenty-eight different head and neck muscle samples were acquired post-mortem from a female subject (34 years) and uvula and palatopharyngeus muscles were acquired from additional five subjects (two males, three females, mean age 54 years). For comparison, autopsies and biopsies from two limb muscles of healthy subjects were acquired. The muscles were analyzed for cytoskeletal intermediate filament protein desmin with immunohistochemical methods. Results. Our findings revealed that while all limb muscles showed immunoreaction for the antibodies directed against the protein desmin, a subpopulation of head and neck muscle fibers lacked or had a faint immunoreaction for desmin. The highest proportion of muscle fibers lacking desmin were observed in the laryngeal (22.6%) and infrahyoid (19.1%) muscle groups, while the lowest proportions were found among jaw muscles (mean 0.7%). Conclusions. The result shows that head and neck muscles in general have a unique cytoskeletal build-up compared to limb muscles highlighting a functional evolutionary adaptation of these muscles.
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