title: Influence of muscle anatomical cross-sectional area on the moment arm length of the triceps brachii muscle at the elbow joint.
abstract: The purpose of this study was to test the hypothesis that the musculotendon moment arm length is affected by the muscle anatomical cross-sectional area. The moment arm length of the triceps brachii (TB) muscle at 30°, 50°, 70°, 90°, 110° elbow flexion positions was measured in sagittal magnetic resonance images (MRI) of 18 subjects as the perpendicular distance between the center of the pulley of the humerus to the line through the center of the TB tendon. The moment arm increased as the elbow flexion angle decreased, from 1.74±0.13 cm at 110° to 2.39±0.14 cm at 30°. The maximal anatomical cross-sectional area of the TB muscle was significantly correlated with the moment arms at all joint positions (r=0.545-0.803, p<0.05). Furthermore, the circumference of the upper arm was also significantly correlated with the moment arms at all joint positions, except for 70° (r=0.504-0.702, p<0.05). These results indicate that the moment arm length of the TB muscle is affected by the muscle anatomical cross-sectional area.
authors.affiliation: Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan. sugisaki@aoni.waseda.jp
authors.forename: Norihide
authors.initials: N
authors.lastname: Sugisaki
authors.forename: Taku
authors.initials: T
authors.lastname: Wakahara
authors.forename: Naokazu
authors.initials: N
authors.lastname: Miyamoto
authors.forename: Koichiro
authors.initials: K
authors.lastname: Murata
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kanehisa
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Fukunaga
mesh_terms: D000328:Adult; D019412:Anatomy, Cross-Sectional; D001132:Arm / Q000033:anatomy & histology* / Q000502:physiology*; D001696:Biomechanical Phenomena; D004551:Elbow Joint / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology; D013710:Tendons / Q000033:anatomy & histology / Q000502:physiology; D055815:Young Adult