The moment arm of a muscle’s force represents the muscle’s leverage or mechanical advantage in producing a joint moment. It is indicative of the muscle’s potential to contribute to actuation of a joint in a particular joint motion direction, and defines the role of the muscle, for example as a joint flexor or abductor. The aims of this study were, firstly, to measure the moment arms of the flexors and extensor muscles of the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints, and the moment arms of the major abductors and adductor muscles of the metacarpophalangeal (MCP) of each finger in the hand using the tendon-excursion method; secondly, to assess the effect of change in joint angle on these moment arms; and thirdly, to determine if there are differences in a given flexor or extensor’s muscle moment arms between the joints it spans on a given finger, and across its tendon slips to multiple fingers. The tendon-excursion method was used to measure instantaneous muscle moment arms in nine fresh-frozen entire forearm cadaver specimens. Flexion angle was found to have significant effects on the moment arms of the extensor muscles at the MCP and PIP joints (p<0.05). In contrast, the digital flexor muscles maintained relatively constant moment arms through the range of flexion. The moment arms of the digital flexors and extensors spanning multiple joints in a finger were largest at the MCP joints and smallest at the DIP joints. The findings demonstrate greater torque generating capacity for tasks such as grasping at the proximal interphalangeal joints, and smaller torque capacity for finer movement control at the distal interphalangeal joints. The dataset generated in this study may be useful in the development and validation of computational models used in surgical planning, and rehabilitation.

肌肉力量的力矩臂代表了肌肉在产生关节力矩时的杠杆作用或机械优势。它表明了肌肉在特定关节运动方向上促成关节动作的潜力，并定义了肌肉的作用，例如作为关节屈肌或外展肌。这项研究的目的是，首先，测量掌指（MCP），近指指间（PIP）和远端指间指（DIP）关节的屈肌和伸肌的弯臂，以及主要外展肌和内收肌的弯臂使用腱偏移法的手的每个手指的掌指肌肉（MCP）；其次，评估关节角改变对这些力矩臂的影响；第三，确定跨过给定手指的关节之间的给定屈肌或伸肌的肌力臂是否存在差异，并且跨过肌腱滑向多个手指。肌腱偏移法用于测量九个新鲜冷冻的整个前臂尸体标本中的瞬时肌肉力矩臂。发现屈曲角度对MCP和PIP关节伸肌的伸直臂有重要影响（p <0.05）。相反，数字屈肌在整个屈曲范围内保持相对恒定的力矩臂。跨手指多个关节的数字屈肌和伸肌的力矩臂在MCP关节处最大，而在DIP关节处最小。研究结果表明，更大的扭矩产生能力可用于抓握近端指间关节，较小的扭矩容量，以更好地控制远端指间关节的运动。在这项研究中生成的数据集可能对开发和验证用于外科手术计划和康复的计算模型有用。