Article

Changes in pennation with joint angle and muscle torque: in vivo measurements in human brachialis muscle.

Prince of Wales Medical Research Institute, University of New South Wales, Sydney, Australia.
The Journal of Physiology (Impact Factor: 4.54). 05/1995; 484 ( Pt 2):523-32. DOI: 10.1113/jphysiol.1995.sp020683
Source: PubMed

ABSTRACT 1. Estimates of pennation in human muscles are usually obtained from cadavers. In this study, pennation of human brachialis was measured in vivo using sonography. Effects of static and dynamic changes in elbow angle and torque were investigated. 2. Pennation was measured in eight subjects using an 80 mm, 5 MHz, linear-array ultrasound transducer to generate sagittal images of the brachialis during maximal and submaximal isometric contractions at various elbow angles. It was shown that estimates of pennation were reproducible, representative of measurements made throughout the belly of the muscle and not distorted by compression of the muscle with the transducer or rotation of the muscle out of the plane of the transducer. 3. Mean resting pennation was 9.0 +/- 2.0 deg (S.D., range 6.5-12.9 deg). When the muscle was relaxed there was no effect of elbow angle on pennation. However, during a maximal isometric contraction (MVC), with the elbow flexed to 90 deg, pennation increased non-linearly with elbow torque to between 22 and 30 deg (mean 24.7 +/- 2.4 deg). The effect of increasing torque was small when the elbow was fully extended. The relationship between elbow angle, elbow torque and brachialis pennation suggests that the relaxed brachialis muscle is slack over much of its physiological range of lengths. 4. There was no hysteresis in the relationship between torque and pennation during slow isometric contractions (0.2 MVC s-1), and the relationship between elbow angle and pennation was similar during slow shortening and lengthening contractions. 5. Two consequences follow from these findings. Firstly, intramuscular mechanics are complex and simple planar models of muscles underestimate the increases in pennation which occur during muscle contraction. Second, spindle afferents from relaxed muscles may not encode joint angle over the full range of movement.

0 Bookmarks
 · 
171 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to investigate the effects of Evjenth-Hamberg stretching on the active range of motion (ROM) of the hip joint and the pennation angle of the semitendinosus muscle. Eighty healthy adults participated in this study. The active ROM of the hip joint was measured by a goniometer and the pennation angle of the semitendinosus muscle was measured by ultrasonographic imaging (USI). Both ROM and pennation angle were recorded before and after the static stretching and the Evjenth-Hamberg stretching, respectively. Data were analyzed using paired t-lest and independent t-test at p
    01/2010; 17(2).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic resonance images and ultrasound images were used to examine the architecture of the distal biceps brachii muscle in 12 unimpaired subjects. The distal biceps brachii tendon continued as an internal aponeurosis that spanned 34± 4% of the length of the biceps brachii long head muscle on average. The distal muscle fascicles inserted at angles to this aponeurosis; fascicles anterior to the aponeurosis inserted at a significantly greater (p ≤ 0.05) angle (17°) than the fascicles posterior to the aponeurosis (14°) in the distal 2 cm of muscle when the elbow was extended. Mean fascicle insertion angles were on average 3–4° greater with the elbow flexed 90° against a 5% maximum voluntary contraction load as compared to their values with the elbow extended. These data provide the basis for designing experiments to measure muscle and tendon motion in vivo.
    Journal of Mechanics in Medicine and Biology 11/2011; 02(03n04). DOI:10.1142/S0219519402000484 · 0.80 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Diagnostic musculoskeletal ultrasound has potential clinical utility in characterizing pathological muscle tissue. Sonography has been long proposed as method of assessing muscle damage due to neuromuscular diseases such as muscular dystrophy, and more recently, changes in body and tissue composition associated with muscle wasting disorders such as sarcopenia. The use of quantitative ultrasound as an adjunct diagnostic procedure has different technical challenges than the traditional use of ultrasound in clinical medicine. Operator-dependent technique and variation are critical considerations when obtaining measures of echointensity (i.e., tissue composition estimates) and tissue dimensions (i.e., muscle thickness) – key elements of the ultrasound assessment of muscular dystrophy and sarcopenia. The use of calibration phantoms and force-feedback augmented ultrasound may be viable methods of providing operator training and augmenting real-time ultrasound measurement consistency. The standardization of specific assessment techniques, and the development of a means to foster measurement reliability in clinical environments, may increase the utilization of this non-invasive, low-risk, and inexpensive imaging modality in the management of muscle disorders. http://journal.frontiersin.org/Journal/10.3389/fnagi.2014.00172/full
    Frontiers in Aging Neuroscience 07/2014; 6. DOI:10.3389/fnagi.2014.00172 · 2.84 Impact Factor

Full-text (2 Sources)

Download
42 Downloads
Available from
Jun 3, 2014