Upper extremity kinetics during Lofstrand crutch-assisted gait

A three-dimensional (3D) biomechanical model was developed to determine upper extremity kinematics and kinetics of persons walking with forearm crutches. Six-component load cells and strain gauges were installed in the crutches to determine crutch forces. A six-camera VICON motion system was used to acquire coordinate data from 24 reflective markers attached to the upper extremities and crutches. Joint axes for the wrist, elbow, and glenohumeral joints were defined and joint forces and moments were determined using inverse dynamics. Accuracy of the crutch instrumentation was established by simultaneously collecting force data from a Kistler forceplate and each crutch during crutch-assisted gait with the respective crutch tip contacting the forceplate. In order to demonstrate the application of this biomechanical model, upper extremity weight bearing forces, joint motion, and stride characteristics were recorded from a subject with T-12 incomplete spinal cord injury (SCI), using a crutch-assisted reciprocal four-point gait pattern. The peak net joint forces and moments were greater for the right arm opposite the weaker left lower extremity. The largest joint forces were directed superiorly (Fz) and the asymmetrical pattern of crutch use was consistent with lower extremity strength differences. During left leg weight acceptance, increased right wrist extension motion and moment were recorded, which may contribute to wrist pathology.     

An EMG-driven model of the upper extremity and estimation of long head biceps force

An electromyography (EMG) driven model of the upper extremity has been developed that incorporates musculoskeletal geometry of the glenohumeral and elbow joints, estimated relevant physiologic muscle parameters including optimal muscle lengths, and EMG activity. The model is designed to predict forces in muscles spanning the glenohumeral joint resulting from functionally relevant tasks. The model is composed of four sub-models that comprise a mathematical as well as graphical three-dimensional representation of the upper extremity: a musculoskeletal model for estimation of muscle-tendon lengths and moment arms, a Hill-based muscle force model, a model for estimating optimal muscle lengths, and a model for estimation of muscle activation from EMG signal of the biceps. The purpose of this paper is to describe the components of the model, as well as the data required to drive the model. Collection of data is described in the context of applying the model to determine biceps muscle forces for testing of functional tasks. Results obtained from applying the model to analyze the functional tasks are summarized, and model strengths and limitations are discussed.     

Force- and moment-generating capacities of muscles in the distal forelimb of the horse

A detailed musculoskeletal model of the distal equine forelimb was developed to study the influence of musculoskeletal geometry (i.e. muscle paths) and muscle physiology (i.e. force-length properties) on the force- and moment-generating capacities of muscles crossing the carpal and metacarpophalangeal joints. The distal forelimb skeleton was represented as a five degree-of-freedom kinematic linkage comprised of eight bones (humerus, radius and ulna combined, proximal carpus, distal carpus, metacarpus, proximal phalanx, intermediate phalanx and distal phalanx) and seven joints (elbow, radiocarpal, intercarpal, carpometacarpal, metacarpophalangeal (MCP), proximal interphalangeal (pastern) and distal interphalangeal (coffin)). Bone surfaces were reconstructed from computed tomography scans obtained from the left forelimb of a Thoroughbred horse. The model was actuated by nine muscle-tendon units. Each unit was represented as a three-element Hill-type muscle in series with an elastic tendon. Architectural parameters specifying the force-producing properties of each muscle-tendon unit were found by dissecting seven forelimbs from five Thoroughbred horses. Maximum isometric moments were calculated for a wide range of joint angles by fully activating the extensor and flexor muscles crossing the carpus and MCP joint. Peak isometric moments generated by the flexor muscles were an order of magnitude greater than those generated by the extensor muscles at both the carpus and the MCP joint. For each flexor muscle in the model, the shape of the maximum isometric joint moment-angle curve was dominated by the variation in muscle force. By contrast, the moment-angle curves for the muscles that extend the MCP joint were determined mainly by the variation in muscle moment arms. The suspensory and check ligaments contributed more than half of the total support moment developed about the MCP joint in the model. When combined with appropriate in vivo measurements of joint kinematics and ground-reaction forces, the model may be used to determine muscle-tendon and joint-reaction forces generated during gait.     

Probabilistic Modeling of Knee Muscle Moment Arms: Effects of Methods,Origin–Insertion,and Kinematic Variability

In musculoskeletal modeling, reliable estimates of muscle moment arms are an important step in accurately predicting muscle forces and joint moments. The degree of agreement between the two common methods of calculating moment arms—tendon excursion (TE) and geometric origin–insertion, is currently unknown for the muscles crossing the knee joint. Further, measured moment arm data are subject to variability in estimation of attachment sites as points from irregular surfaces on the bones, and due to differences in joint kinematics observed in vivo. Thus, the objectives of the present study were to compare moment arms of major muscles crossing the knee joint obtained from TE and geometric methods using a finite element-based lower extremity model, and to quantify the effects of potential muscle origin–insertion and tibiofemoral kinematic variability on the predicted moment arms using probabilistic methods. A semiconstrained, fixed bearing, posterior cruciate-retaining total knee arthroplasty was included due to available in vivo kinematic data. In this study, muscle origin and insertion locations and kinematic variables were represented as normal distributions with standard deviations of 5 mm for origin–insertion locations and up to 1.6 mm and 3.0° for the kinematic parameters. Agreement between the deterministic moment arm calculations from the two methods was excellent for the flexors, while differences in trends and magnitudes were observed for the extensor muscles. Model-predicted deterministic moment arms from both methods agreed reasonably with the experimental values from available literature. The uncertainty in input parameters resulted in substantial variability in predicted moment arms, with the size of 1–99% confidence interval being up to 41.3 and 35.8 mm for the TE and geometric methods, respectively. The sizeable range of moment arm predictions and associated excursions has the potential to affect a muscle’s operating range on the force–length curve, thus affecting joint moments. In this study, moment arm predictions were more dependent on muscle origin–insertion locations than the kinematic variables. The important parameters from the TE method were the origin and insertion locations in the sagittal plane, while the insertion location in the sagittal plane was the dominant parameter using the geometric method.     

基于Hill肌肉模型的人体关节力矩智能预测

目的人体关节力矩是康复评估和人机交互中非常关键的因素之一。它可以通过人工神经网络(artificial neural network,ANN)模型以肌电等信号作为输入进行预测,但是由于人体结构的复杂性导致缺乏有效方法确定ANN模型的输入变量。为此本文提出了一种基于Hill肌肉模型获取关节力矩神经网络预测最优输入变量的方法。方法采用Hill肌肉模型结合人体几何学知识建立关节力矩,智能预测输入输出关系的数学模型,把Hill肌肉模型中肌肉纤维长度和收缩速度,以及以关节自由度为支点的肌肉力臂等不可活体测量的输入变量,转换成关节自由度所关联肌肉的肌电信号(electromyography,EMG)以及这些肌肉所驱动关节自由度角度和角速度等可在线测量的变量。实验中以本文获取的变量作为极限学习机(extreme learning machine,ELM)的输入,对由1位在跑步机上以0.4、0.5、0.6、0.7和0.8 m/s等5个不同速度行走的右下肢偏瘫患者所获的数据进行测试。为了评估本文所提方法智能预测的泛化能力,实验在两个不同的泛化水平下进行,它们分别是只把3个低速数据(0.4、0.5和0.6 m/s)和全部5个速度的数据用于神经网络的训练并预测所有速度下的关节力矩值。实验通过预测值与反向动力学计算值之间的归一化绝对误差和互相关系数评估。结果本文获取的输入变量与其他关节角和角速度作为输入的方法相比,预测关节力矩值更精准。除右踝关节内外翻外,其他关节力矩预测结果的最大归一化绝对误差为12.93%,最小平均互相关系数为0.89。结论该方法比目前通用多体反向动力学的输入变量少,且可实现关节力矩值的在线预测,为运动康复中实时步态分析和外骨骼机器人控制提供技术支持。     

Muscle moment arms of pelvic limb muscles of the ostrich (Struthio camelus)

Muscle moment arms were measured for major muscles of the pelvic limb of the ostrich (Struthio camelus) in order to assess specific functional behaviour and to apply this to locomotor performance. Pelvic limbs of six juvenile ostriches were used for this study. The tendon travel technique was used to measure moment arms of 21 muscles at the hip, knee, ankle and metatarsophalangeal joints throughout the ranges of motion observed during level running. Six of the 21 muscles measured were found to have moment arms that did not change with joint angle, whilst the remainder all demonstrated angle-dependent changes for at least one of the joints crossed. Moment arm lengths tended to be longest for the large proximal muscles, whilst the largest relative changes were found for the moment arms of the distal muscles. For muscles where moment arm varied with joint angle: all hip muscles were found to have increasing moment arms with extension of the joint, knee flexors were found to have moment arms that increased with extension, knee extensor moment arms were found to increase with flexion and ankle extensor moment arms increased with extension. The greatest relative changes were observed in the flexors of the metatarsophalangeal joint, for which a three-fold increase in moment arm was observed from flexion to full extension. Changes in muscle moment arm through the range of motion studied appear to optimize muscle function during stance phase, increasing the effective mechanical advantage of these muscles.     

Activation and intermuscular coherence of distal arm muscles during proximal muscle contraction

In the human upper extremity (UE), unintended effects of proximal muscle activation on muscles controlling the hand could be an important aspect of motor control due to the necessary coordination of distal and proximal segments during functional activities. This study aimed to elucidate the effects of concurrent activation of elbow muscles on the coordination between hand muscles performing a grip task. Eleven healthy subjects performed precision grip tasks while a constant extension or flexion moment was applied to their elbow joints, inducing a sustained submaximal contraction of elbow muscles to counter the applied torque. Activation of four hand muscles was measured during each task condition using surface electromyography (EMG). When concurrent activation of elbow muscles was induced, significant changes in the activation levels of the hand muscles were observed, with greater effects on the extrinsic finger extensor (23.2 % increase under 30 % elbow extensor activation; p = 0.003) than extrinsic finger flexor (14.2 % increase under 30 % elbow flexor activation; p = 0.130). Elbow muscle activation also induced involuntary changes in the intrinsic thumb flexor activation (44.6 % increase under 30 % elbow extensor activation; p = 0.005). EMG–EMG coherence analyses revealed that elbow muscle activation significantly reduced intermuscular coherence between distal muscle pairs, with its greatest effects on coherence in the β-band (13–25 Hz) (average of 17 % decrease under 30 % elbow flexor activation). The results of this study provide evidence for involuntary, muscle-specific interactions between distal and proximal UE muscles, which may contribute to UE motor performance in health and disease.     

Importance of Consistent Datasets in Musculoskeletal Modelling: A Study of the Hand and Wrist

Hand musculoskeletal models provide a valuable insight into the loads withstood by the upper limb; however, their development remains challenging because there are few datasets describing both the musculoskeletal geometry and muscle morphology from the elbow to the finger tips. Clinical imaging, optical motion capture and microscopy were used to create a dataset from a single specimen. Subsequently, a musculoskeletal model of the wrist was developed based on these data to estimate muscle tensions and to demonstrate the potential of the provided parameters. Tendon excursions and moment arms predicted by this model were in agreement with previously reported experimental data. When simulating a flexion–extension motion, muscle forces reached 90 N among extensors and a co-contraction of flexors, amounting to 62.6 N, was estimated by the model. Two alternative musculoskeletal models were also created based on anatomical data available in the literature to illustrate the effect of combining incomplete datasets. Compared to the initial model, the intensities and load sharing of the muscles estimated by the two alternative models differed by up to 180% for a single muscle. This confirms the importance of using a single source of anatomical data when developing such models.     

Detection of simultaneous movement at two human arm joints

To detect joint movement, the brain relies on sensory signals from muscle spindles that sense the lengthening and shortening of the muscles. For single-joint muscles, the unique relationship between joint angle and muscle length makes this relatively straightforward. However, many muscles cross more than one joint, making their spindle signals potentially ambiguous, particularly when these joints move in opposite directions. We show here that simultaneous movement at adjacent joints sharing biarticular muscles affects the threshold for detecting movements at either joint whereas it has no effect for non-adjacent joints. The angular displacements required for 70% correct detection were determined in 12 subjects for movements imposed on the shoulder, elbow and wrist at angular velocities of 0.25–2 deg s⁻¹. When moved in isolation, detection thresholds at each joint were similar to those reported previously. When movements were imposed on the shoulder and wrist simultaneously, there were no changes in the thresholds for detecting movement at either joint. In contrast, when movements in opposite directions at velocities greater than 0.5 deg s⁻¹ were imposed on the elbow and wrist simultaneously, thresholds increased. At 2 deg s⁻¹, the displacement threshold was approximately doubled. Thresholds decreased when these adjacent joints moved in the same direction. When these joints moved in opposite directions, subjects more frequently perceived incorrect movements in the opposite direction to the actual. We conclude that the brain uses potentially ambiguous signals from biarticular muscles for kinaesthesia and that this limits acuity for detecting joint movement when adjacent joints are moved simultaneously.     

Topsy-turvy locomotion: biomechanical specializations of the elbow in suspended quadrupeds reflect inverted gravitational constraints

Some tetrapods hang upside down from tree branches when moving horizontally. The ability to walk in quadrupedal suspension has been acquired independently in at least 14 mammalian lineages. During the stance (supportive) phase of quadrupedal suspension, the elbow joint flexor muscles (not the extensors as in upright vertebrates moving overground) are expected to contract to maintain the flexed limb posture. Therefore muscular control in inverted, suspended quadrupeds may require changes of muscle control, and even morphologies, to conditions opposite to those in upright animals. However, the relationships between musculoskeletal morphologies and elbow joint postures during the stance phase in suspended quadrupeds have not been investigated. Our analysis comparing postures and skeletal morphologies in Choloepus (Pilosa), Pteropus (Chiroptera), Nycticebus (Primates) and Cynocephalus (Dermoptera) revealed that the elbow joints of these animals were kept at flexed angles of 70-100 ° during the stance phase of quadrupedal suspension. At these joint angles the moment arms of the elbow joint flexors were roughly maximized, optimizing that component of antigravity support. Our additional measurements from various mammalian species show that suspended quadrupeds have relatively small extensor/flexor ratios in both muscle masses and maximum moment arms. Thus, in contrast to the pattern in normal terrestrial quadrupeds, suspended quadrupeds emphasize flexor over extensor muscles for body support. This condition has evolved independently multiple times, attendant with a loss or reduction of the ability to move in normal upright postures.     

Reprogramming of muscle activation patterns at the wrist in compensation for elbow reaction torques during planar two-joint arm movements

The relationship between wrist kinematics, dynamics and the pattern of muscle activation were examined during a two-joint planar movement in which the two joints moved in opposite directions, i.e. elbow flexion/wrist extension and elbow extension/wrist flexion. Elbow movements (ranging from 10 to 70 deg) and wrist movements (ranging from 10 to 50 deg) were performed during a visual, step-tracking task in which subjects were required to attend to the initial and final angles at each joint. As the elbow amplitude increased, wrist movement duration increased and the wrist movement trajectories became quite variable. Analysis of the torques acting at the wrist joint showed that elbow movements produced reaction torques acting in the same direction as the intended wrist movement. Distinct patterns of muscle activation were observed at the wrist joint that were dependent on the relative magnitude of the elbow reaction torque in relation to the net wrist torque. When the magnitude of the elbow reaction torque was quite small, the wrist agonist was activated first. As the magnitude of the elbow reaction torque increased, activity in the wrist agonist decreased significantly. In conditions where the elbow reaction torque was much larger than the net wrist torque, the wrist muscle torque reversed direction to oppose the intended movement. This reversal of wrist muscle torque was directly associated with a change in the pattern of muscle activation where the wrist antagonist was activated prior to the wrist agonist. Our findings indicate that motion of the elbow joint is an important consideration in planning wrist movement. Specifically, the selection of muscle activation patterns at the wrist is dependent on the relative magnitude and direction of the elbow reaction torque in relation to the direction of wrist motion.     

Morphological analysis of the hindlimb in apes and humans. II. Moment arms

Flexion/extension moment arms were obtained for the major muscles crossing the hip, knee and ankle joints in the orang-utan, gibbon, gorilla (Eastern and Western lowland) and bonobo. Moment arms varied with joint motion and were generally longer in proximal limb muscles than distal limb muscles. The shape of the moment arm curves (i.e. the plots of moment arm against joint angle) differed in different hindlimb muscles and in the same muscle in different subjects (both in the same and in different ape species). Most moment arms increased with increasing joint flexion, a finding which may be understood in the context of the employment of flexed postures by most non-human apes (except orang-utans) during both terrestrial and arboreal locomotion. When compared with humans, non-human great apes tended to have muscles better designed for moving the joints through large ranges. This was particularly true of the pedal digital flexors in orang-utans. In gibbons, the only lesser ape studied here, many of the moment arms measured were relatively short compared with those of great apes. This study was performed on a small sample of apes and thus differences noted here warrant further investigation in larger populations.     

Muscle moment arms of the gibbon hind limb: implications for hylobatid locomotion

Muscles facilitate skeletal movement via the production of a torque or moment about a joint. The magnitude of the moment produced depends on both the force of muscular contraction and the size of the moment arm used to rotate the joint. Hence, larger muscle moment arms generate larger joint torques and forces at the point of application. The moment arms of a number of gibbon hind limb muscles were measured on four cadaveric specimens (one Hylobates lar, one H. moloch and two H. syndactylus). The tendon travel technique was used, utilizing an electro‐goniometer and a linear voltage displacement transducer. The data were analysed using a technique based on a differentiated cubic spline and normalized to remove the effect of body size. The data demonstrated a functional differentiation between voluminous muscles with short fascicles having small muscle moment arms and muscles with longer fascicles and comparatively smaller physiological cross‐sectional area having longer muscle moment arms. The functional implications of these particular configurations were simulated using a simple geometric fascicle strain model that predicts that the rectus femoris and gastrocnemius muscles are more likely to act primarily at their distal joints (knee and ankle, respectively) because they have short fascicles. The data also show that the main hip and knee extensors maintain a very small moment arm throughout the range of joint angles seen in the locomotion of gibbons, which (coupled to voluminous, short‐fascicled muscles) might help facilitate rapid joint rotation during powerful movements.     

Muscle moment arms and function of the siamang forelimb during brachiation

Moment arms have an important modulating impact on muscle function, as they represent the capacity of the muscle to convert muscle action into limb movements. In the current paper, we provide muscle moment arm data of the forelimb of four siamangs, collected by detailed dissections on unfixed cadavers. The aim of this study is to assess the role of different forelimb muscles during brachiation. Moment arm data are compared with similar published data of non‐brachiating primates such as macaques, chimpanzees and humans. Our data show that shoulder adductors and endorotators and the elbow flexors are built for force generation, whereas the shoulder abductors, flexors and exorotators are best suited to gain speed and to change direction. Compared to non‐brachiating species, both elbow and wrist flexors are particularly noticeable in terms of moment of force‐generating capacity. However, the moment of force‐generating capacity of the elbow extensor is not negligible, which indicates that the triceps also plays an active role, especially at the end of the support phase. Except for the elbow flexors, all muscles reach their maximum moment of force‐generating capacity during the support phase of brachiation. When brachiating on a more complex setup, the siamang will flex the elbows to angles that induce maximum moment arms as well.     

A three-dimensional kinematic model of the human long finger and the muscles that actuate it

A kinematic model of the human long finger and the six muscles that actuate it is presented. The model transforms finger pose into estimates of muscle excursions and fingertip location. The effects of abduction/adduction about the metacarpo-phalangeal joint are accounted for, as are the effects of flexion of the three finger joints. A set of parameters are provided which approximate kinematics of the segments and muscles of a cadaver finger over the range of finger poses humans normally assume.     

人服系统上肢交互生物力学仿真模型

目的 通过建立人-舱外服上肢交互生物力学仿真模型计算穿着舱外服后航天员上肢关节力矩和肌肉力，满足出舱活动风险评估的需求。方法 分别建立舱外服手臂的刚体运动学模型和关节阻尼力矩迟滞模型以描述舱外服关节的运动和力学特性。通过对舱外航天服肘部和人体肘部位置进行约束实现人体和舱外服手臂之间的运动学耦合，利用虚拟反作用力元实现两者之间的动力学耦合，在反向运动生物力学架构下建立一体化仿真模型。利用该模型对宇航员穿着加压、未加压舱外服和不穿着舱外服3种工况下肘弯曲/伸展进行仿真案例分析。结果 3种工况下肱二头肌的预测肌肉激活和积分肌电的相关性分别为0.86、0.71、0.65，肱三头肌对应的相关性分别为0.75、0.61、0.60，采用预测肌肉激活和积分肌电的一致性定性验证了模型的正确性，利用舱外服肘关节阻尼力矩与人体肘关节肌肉承受力矩之间的一致性验证了模型的合理性。结论 该人服系统上肢交互生物力学仿真模型能有效计算航天员穿着舱外服后的上肢关节力矩和肌肉力，且仿真结果和实验表明，加压后舱外服关节阻尼力矩造成较大的人体关节力矩和肌肉负荷，为航天员出舱活动中的体力负荷和骨肌风险评估提供方法学支撑。     

人服系统上肢交互生物力学仿真模型

目的通过建立人-舱外服上肢交互生物力学仿真模型计算穿着舱外服后航天员上肢关节力矩和肌肉力,满足出舱活动风险评估的需求。方法分别建立舱外服手臂的刚体运动学模型和关节阻尼力矩迟滞模型以描述舱外服关节的运动和力学特性。通过对舱外航天服肘部和人体肘部位置进行约束实现人体和舱外服手臂之间的运动学耦合,利用虚拟反作用力元实现两者之间的动力学耦合,在反向运动生物力学架构下建立一体化仿真模型。利用该模型对宇航员穿着加压、未加压舱外服和不穿着舱外服3种工况下肘弯曲/伸展进行仿真案例分析。结果3种工况下肱二头肌的预测肌肉激活和积分肌电的相关性分别为0.86、0.71、0.65,肱三头肌对应的相关性分别为0.75、0.61、0.60,采用预测肌肉激活和积分肌电的一致性定性验证了模型的正确性,利用舱外服肘关节阻尼力矩与人体肘关节肌肉承受力矩之间的一致性验证了模型的合理性。结论该人服系统上肢交互生物力学仿真模型能有效计算航天员穿着舱外服后的上肢关节力矩和肌肉力,且仿真结果和实验表明,加压后舱外服关节阻尼力矩造成较大的人体关节力矩和肌肉负荷,为航天员出舱活动中的体力负荷和骨肌风险评估提供方法学支撑。     

Selection of muscles for initiation of planar,three-joint arm movements with different final orientations of the hand

Muscle activities and joint rotations were examined at the shoulder, elbow, and wrist joints for pointing movements to targets in the horizontal plane. In such movements, multiple arm configurations are possible for a given target location. Thus, starting from the same initial configuration and for the same target location in space, the joint excursions could be varied. When no constraints were placed on the final orientation of the hand, the choice of muscles initially activated at the wrist joint was consistent with a function to resist inertial effects of proximal segment motion on the wrist joint. When subjects were asked to produce different final orientations of the hand for the same target location, the initial choice of muscles at the three joints was preserved in most trials, whether wrist flexion or extension was required to reach the final hand orientation. The relative onset times of muscle activity at the different joints were also not correlated with wrist excursion. This suggests a predetermined initial selection of muscles that is related to target location, not to joint angular excursion. The fact that the required final hand orientation was nevertheless achieved suggests that the planning of these pointing movements is not a unitary process, but is comprised of two components: a fixed initial muscle selection for a given target location in space, and a selection appropriate for the required joint excursions.     

人服系统上肢交互生物力学仿真模型

目的 通过建立人-舱外服上肢交互生物力学仿真模型计算穿着舱外服后航天员上肢关节力矩和肌肉力,满足出舱活动风险评估的需求。方法 分别建立舱外服手臂的刚体运动学模型和关节阻尼力矩迟滞模型以描述舱外服关节的运动和力学特性。通过对舱外航天服肘部和人体肘部位置进行约束实现人体和舱外服手臂之间的运动学耦合,利用虚拟反作用力元实现两者之间的动力学耦合,在反向运动生物力学架构下建立一体化仿真模型。利用该模型对宇航员穿着加压、未加压舱外服和不穿着舱外服3种工况下肘弯曲/伸展进行仿真案例分析。结果 3种工况下肱二头肌的预测肌肉激活和积分肌电的相关性分别为0.86、0.71、0.65,肱三头肌对应的相关性分别为0.75、0.61、0.60,采用预测肌肉激活和积分肌电的一致性定性验证了模型的正确性,利用舱外服肘关节阻尼力矩与人体肘关节肌肉承受力矩之间的一致性验证了模型的合理性。结论 该人服系统上肢交互生物力学仿真模型能有效计算航天员穿着舱外服后的上肢关节力矩和肌肉力,且仿真结果和实验表明,加压后舱外服关节阻尼力矩造成较大的人体关节力矩和肌肉负荷,为航天员出舱活动中的体力负荷和骨肌风险评估提供方法学支撑。     

人腕关节动力肌腱的力臂值及意义探讨

目的：测量人腕关节主要动力肌腱在腕运动过程中的力臂的大小。方法：运用７只新鲜成人尸体上肢标本,将运动腕关节的肌腱和旋转电压计相连,在腕关节分别从屈曲至伸直,桡偏至尺偏过程中,用计算机同时记录腕动力肌腱滑动距离和腕运动角度,根据腱滑动距离和腕运动角度计算出肌腱平均力臂和力臂变化。结果：桡侧腕长伸肌腱的腕桡偏力臂最大,桡侧腕短伸肌腱的伸腕力臂最大,尺侧腕伸肌腱和腕尺偏力臂最大,而伸腕力臂很小,桡侧、尺