title: Ultrasound and analysis of the deformation patterns of the masseter muscle: comparing surgical anatomy, ultrasound and functional anatomy.
abstract: OBJECTIVE
  We have tried to demonstrate whether the analysis of the muscle strain allows us to identify the three distinct functional areas of the architecture of the masseter, as one would see them by performing or viewing an anatomical dissection of said muscle, and whether these sections have behave differently in terms of origin and coping of the strain they face (quantitative analysis).
  
  
  METHODS
  This work has been elaborated by the use of an ultrasound machine (MicrUs ext-1H Telemed Medical Systems Milano) and a linear probe (L12-5l40S-3 5-12 MHz 40 mm) which allowed us to record a 45 frame per second video (DCM). Videos has been elaborated by use of an ultrasound machine (MicrUs ext-1H Telemed Medical Systems Milano) and a linear probe (L12-5l40S-3 5-12 MHz 40 mm) which allowed us to record a 45 frame per second video (DCM). We applied to the resulting video a software (Mudy 1.7.7.2 AMID Sulmona Italy) for the analysis of muscle deformation patters (contraction, dilatation, cross-plane, vertical strain, horizontal strain, vertical shear, horizontal shear, horizontal displacement, vertical displacement). The number of videos of masseter muscles in contraction at maximum exertion due to dental clenching made during this research is around 12,000. Out of these we chose 1,200 videos which examine 200 patients (100 females, 100 males).
  
  
  RESULTS
  The deformation pattern analysis of the skeletal muscle on ultrasound basis seems to be an adequate instrument to use during the investigation of the functional structure of the masseter muscle given its ability to highlight the distinct activity of each separate part of the muscle.
  
  
  CONCLUSIONS
  Moreover the strain does not apply to the muscle uniformly; instead it varies according to the observed area.
authors.affiliation: Medica Libra, Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Busato
authors.affiliation: Department of Radiology, Hospital San Raffaele Turro, Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Balconi
authors.affiliation: Medica Libra, Milano, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Vismara
authors.affiliation: Fondazione Apostolo, Merate, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Bertelè
authors.affiliation: President and Founder of Siach - The International Society of Surgical Anatomy.
authors.forename: G
authors.initials: G
authors.lastname: Garo
authors.affiliation: Director of Siach, Aesthetic Surgeon, Perugia, Italy.
authors.forename: D
authors.initials: D
authors.lastname: DE Gregorio
keywords: biomechanics; deformation pattern; masseter muscle; masticatory organ; strain; ultrasound