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Wrist Flexion (wrist + flexion)
Selected AbstractsfMRI analysis for motor paradigms using EMG-based designs: A validation studyHUMAN BRAIN MAPPING, Issue 11 2007Anne-Fleur van Rootselaar Abstract The goal of the present validation study is to show that continuous surface EMG recorded simultaneously with 3T fMRI can be used to identify local brain activity related to (1) motor tasks, and to (2) muscle activity independently of a specific motor task, i.e. spontaneous (abnormal) movements. Five healthy participants performed a motor task, consisting of posture (low EMG power), and slow (medium EMG power) and fast (high EMG power) wrist flexion,extension movements. Brain activation maps derived from a conventional block design analysis (block-only design) were compared with brain activation maps derived using EMG-based regressors: (1) using the continuous EMG power as a single regressor of interest (EMG-only design) to relate motor performance and brain activity, and (2) using EMG power variability as an additional regressor in the fMRI block design analysis to relate movement variability and brain activity (mathematically) independent of the motor task. The agreement between the identified brain areas for the block-only design and the EMG-only design was excellent for all participants. Additionally, we showed that EMG power variability correlated well with activity in brain areas known to be involved in movement modulation. These innovative EMG-fMRI analysis techniques will allow the application of novel motor paradigms. This is an important step forward in the study of both the normally functioning motor system and the pathophysiological mechanisms in movement disorders. Hum Brain Mapp, 2007. © 2007 Wiley-Liss, Inc. [source] Gliding resistance of the extensor pollicis brevis tendon and abductor pollicis longus tendon within the first dorsal compartment in fixed wrist positionsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2005Keiji Kutsumi Abstract Purpose: While the etiology of de Quervain's disease is unknown, repetitive motion coupled with awkward wrist position and septation within the first dorsal compartment are considered causative factors. We hypothesize that these conditions might produce high gliding resistance, which could then induce micro-damage of the tendons and retinaculum. The purpose of this study was to measure the gliding resistance of the extensor pollicis brevis and abductor pollicis longus tendons within the first dorsal compartment in a human cadaver model. Methods: Fifteen human cadaver wrists, which included eight septation and seven non-septation wrists in the first dorsal compartment, were used. Gliding resistance of the extensor pollicis brevis and abductor pollicis longus tendons was measured in seven wrist positions: 60° extension, 30° extension, 0°, 30° flexion, 60° flexion in neutral deviation and 30° ulnar deviation, 15° radial deviation in neutral extension/flexion. Results: The overall gliding resistance was not different between septation and non-septation wrists (0.21 versus 0.19 N for abductor pollicis longus and 0.21 versus 0.15 N for extensor pollicis brevis, respectively), but there was a significant effect on gliding resistance due to wrist position (p < 0.05) in both tendons. Interaction between wrist position and septation status was observed in the extensor pollicis brevis tendon (p < 0.05). With septation, the gliding resistance of the extensor pollicis brevis was significantly higher in 60° wrist flexion (0.51 N) compared to all other wrist positions tested (all less than 0.26 N) (p < 0.05). In the non-septation group, gliding resistance was significantly higher in 60° flexion (0.20 N) and 60° extension (0.22 N) compared to the other five wrist positions (all less than 0.15 N) (p < 0.05). Although no significant difference was observed, the extensor pollicis brevis tendon with septation tended to have higher gliding resistance than that without septation in wrist flexion. In 60° of wrist flexion the abductor pollicis longus tendon had significantly higher gliding resistance (0.33 N) than the other wrist positions (all less than 0.26 N) (p < 0.05). Conclusions: A combination of septation and wrist position significantly affected extensor pollicis brevis tendon gliding resistance in this cadaver model. These factors may contribute to the development of de Quervain's disease. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Transfer of brachialis branch of musculocutaneous nerve for finger flexion: Anatomic study and case reportMICROSURGERY, Issue 5 2004Yudong Gu M.D. Based on an anatomic study, a transfer of the brachialis muscle branch of the musculocutaneous nerve (BMBMCN) to finger flexor functional fascicles of the median nerve was designed. Preliminary results of clinical application of this new procedure are reported. Dissection of 32 cadaver upper limbs revealed that BMBMCN derives from the musculocutaneous nerve at the distal 1/3 upper arm level. Mostly it is of single-branch type, with an average dissectable length of 5.2 cm. At this level, functional fascicles of finger flexors are located at the posterior 1/3 of the median nerve. BMBMCN can be directly coapted to these finger flexion fascicles. In one case of brachial plexus lower trunk injury, this neurotization procedure was done. No impairment of elbow flexion and wrist flexion was found postoperatively. Recovery of finger and thumb flexion was seen 1 year postoperatively. This neurotization is safe and effective for treating lower trunk injuries. © 2004 Wiley-Liss, Inc. Microsurgery 24:1,5, 2004. [source] Vibration prolongs the cortical silent period in an antagonistic muscleMUSCLE AND NERVE, Issue 6 2009Christian Binder MD Abstract We tested whether the silent period, an indicator of inhibitory neuronal activity, is modulated by muscle vibration. Vibration was applied to the right extensor carpi radialis (ECR) muscle in 17 healthy subjects and, as a control experiment, to the dorsal terminal phalanges in 5 subjects. Data before vibration were compared with those during vibration. The cortical silent period (CSP) was evoked by transcranial magnetic stimuli (TMS) during voluntary wrist flexion or during voluntary wrist extension. TMS-evoked motor potentials (MEPs) of the flexor carpi radialis (FCR) muscle were recorded during muscle relaxation. The mixed nerve silent period (MNSP) was obtained by electrical stimulation of the median nerve during wrist flexion. ECR vibration induced a significant prolongation of the CSP in FCR. CSP increases induced by vibration of the dorsal terminal phalanges were significantly less pronounced. In ECR, the CSP tended to be shortened. MEPs and MNSP remained unchanged. We conclude that vibration enhances inhibitory neuronal properties in a non-vibrated antagonistic muscle, presumably at a supraspinal level. These results may be relevant for the treatment of spasticity of the upper extremity. Muscle Nerve, 2009 [source] Delay in initiation and termination of muscle contraction, motor impairment, and physical disability in upper limb hemiparesisMUSCLE AND NERVE, Issue 4 2002John Chae MD Abstract The purpose of this study was to describe the relationship between the delay in initiation and termination of muscle contraction and clinical measures of motor impairment and physical disability in the affected upper limb of patients with hemiparesis. Electromyographic (EMG) activity of 26 long-term survivors of stroke was recorded during isometric wrist flexion and extension. Upper limb motor impairment and disability were assessed with the Fugl-Meyer motor assessment (FMA) and arm motor ability test (AMAT), respectively. Delay in initiation and termination of muscle contraction was significantly prolonged in the paretic arm. However, the delay was not significantly affected by stroke type, stroke level, side of hemiparesis, or presence of aphasia. Delay in initiation and termination of muscle contraction correlated significantly with FMA and AMAT. Abnormally delayed initiation and termination of muscle contraction may contribute to hemiparetic upper limb motor impairment and physical disability in hemiparetic patients. © 2002 Wiley Periodicals, Inc. 25: 000,000, 2002 [source] Upper limb kinematics and the role of the wrist during stone tool productionAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010E.M. Williams Abstract Past studies have hypothesized that aspects of hominin upper limb morphology are linked to the ability to produce stone tools. However, we lack the data on upper limb motions needed to evaluate the biomechanical context of stone tool production. This study seeks to better understand the biomechanics of stone tool-making by investigating upper limb joint kinematics, focusing on the role of the wrist joint, during simple flake production. We test the hypotheses, based on studies of other upper limb activities (e.g., throwing), that upper limb movements will occur in a proximal-to-distal sequence, culminating in rapid wrist flexion just prior to strike. Data were captured from four amateur knappers during simple flake production using a VICON motion analysis system (50 Hz). Results show that subjects utilized a proximal-to-distal joint sequence and disassociated the shoulder joint from the elbow and wrist joints, suggesting a shared strategy employed in other contexts (e.g., throwing) to increase target accuracy. The knapping strategy included moving the wrist into peak extension (subject peak grand mean = 47.3°) at the beginning of the downswing phase, which facilitated rapid wrist flexion and accelerated the hammerstone toward the nodule. This sequence resulted in the production of significantly more mechanical work, and therefore greater strike forces, than would otherwise be produced. Together these results represent a strategy for increasing knapping efficiency in Homo sapiens and point to aspects of skeletal anatomy that might be examined to assess potential knapping ability and efficiency in fossil hominin taxa. Am J Phys Anthropol 143:134-145, 2010. © 2010 Wiley-Liss, Inc. [source] | |||||||||||||