A dynamic ultrasonographic in vivo study of the musculoaponeurotic architecture of the human masseter muscle

Teodora-Iunia Gheorghe; Roger Leekam; Ernest W N Lam; Susanne Perschbacher; Bernard Liebgott; Anne Maria Reet Agur

doi:10.1016/j.oooo.2021.02.006

A dynamic ultrasonographic in vivo study of the musculoaponeurotic architecture of the human masseter muscle

Oral Surg Oral Med Oral Pathol Oral Radiol. 2021 Nov;132(5):609-615. doi: 10.1016/j.oooo.2021.02.006. Epub 2021 Feb 11.

Authors

Teodora-Iunia Gheorghe¹, Roger Leekam², Ernest W N Lam³, Susanne Perschbacher³, Bernard Liebgott⁴, Anne Maria Reet Agur⁴

Affiliations

¹ Division of Anatomy, Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, ON, Canada; Oral and Maxillofacial Radiology Graduate Program, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada. Electronic address: t.gheorghe@mail.utoronto.ca.
² Division of Anatomy, Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
³ Oral and Maxillofacial Radiology Graduate Program, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada; Graduate Department of Dentistry, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
⁴ Division of Anatomy, Department of Surgery, Faculty of Medicine, University of Toronto, Toronto, ON, Canada; Graduate Department of Dentistry, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.

PMID: 33781750
DOI: 10.1016/j.oooo.2021.02.006

Abstract

Objective: In the present study, we sought to investigate the in vivo musculoaponeurotic architecture of the masseter muscle (MM) volumetrically with ultrasound in asymptomatic participants. It was hypothesized that the mean fiber bundle length (FBL) and mean aponeurotic height of laminae of the MM differ significantly between the relaxed state and maximally contracted state upon elevation of the mandible.

Study design: The MM was investigated volumetrically in 12 male and 12 female asymptomatic participants (mean age, 25.8 ± 4.1 years) using ultrasound. The mean FBL and mean height of aponeuroses in the relaxed and maximally contracted states were compared using paired t tests, with significance established at P ≤ .05. Intrarater reliability was assessed using the intraclass correlation coefficient (ICC).

Results: The MM consisted of the superficial head (SH) and deep head, each arranged in multiple laminae. Fiber bundles extended between superior and inferior aponeuroses and/or bone. Statistically significant differences (P ≤ .05) were observed in mean FBL and in mean height of aponeuroses between the relaxed and contracted states only in superficial laminae of the SH.

Conclusions: These results suggest there is differential contraction of the laminae of the MM in the transition from relaxed to contracted states. Future comparison with pathologic patients can be made on the basis of an established normative database.

MeSH terms

Adult
Female
Humans
Male
Masseter Muscle* / diagnostic imaging
Muscle Contraction*
Reproducibility of Results
Ultrasonography
Young Adult