title: Size and orientation of masticatory muscles in patients with mandibular laterognathism.
abstract: Size measurements of jaw muscles reflect their force capabilities and correlate with facial morphology. Using MRI, we examined the size and orientation of jaw muscles in patients with mandibular laterognathism in comparison with a control group. We hypothesized that the muscles of the deviated side would be smaller than those of the non-deviated side, and that the muscles of both sides would be smaller than in controls. In patients, a comparison of deviated and non-deviated sides showed, in orientation, differences for masseter and medial pterygoid muscles, but, in size, differences only for the masseter muscle. Nevertheless, muscle sizes in patients were much smaller than in controls. Lateral displacement of the mandible can explain the orientation differences, but not the smaller muscle size, in patients. It is possible that the laterodeviation initiates an adaptive process in the entire jaw system, resulting in extensive atrophy of the jaw muscles.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. goto@rad.dent.kyushu-u.ac.jp
authors.forename: T K
authors.initials: TK
authors.lastname: Goto
authors.forename: S
authors.initials: S
authors.lastname: Nishida
authors.forename: M
authors.initials: M
authors.lastname: Yahagi
authors.forename: G E J
authors.initials: GE
authors.lastname: Langenbach
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: K
authors.initials: K
authors.lastname: Tokumori
authors.forename: S
authors.initials: S
authors.lastname: Sakai
authors.forename: H
authors.initials: H
authors.lastname: Yabuuchi
authors.forename: K
authors.initials: K
authors.lastname: Yoshiura
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D019412:Anatomy, Cross-Sectional; D001284:Atrophy; D002508:Cephalometry; D005146:Facial Asymmetry / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008336:Mandibular Diseases / Q000473:pathology*; D008406:Masseter Muscle / Q000473:pathology; D008410:Masticatory Muscles / Q000473:pathology*; D011626:Pterygoid Muscles / Q000473:pathology; D014716:Vertical Dimension