Department of Physiology, College of Medicine, PO Box 210093, University of Arizona, Tucson, AZ 85721-0093, USA.
J Physiol. 2011 Dec 1;589(Pt 23):5595-602. doi: 10.1113/jphysiol.2011.215236. Epub 2011 Oct 17.
Motor units serve both as the mechanical apparatus and the final stage of neural processing through which motor behaviours are enacted. Therefore, knowledge about the contractile properties and organization of the neural inputs to motor units supplying finger muscles is essential for understanding the control strategies underlying the diverse motor functions of the human hand. In this brief review, basic contractile properties of motor units residing in human hand muscles are described. Hand motor units are not readily categorized into the classical physiological types as established in the cat gastrocnemius muscle. In addition, the distribution of descending synaptic inputs to motor nuclei supplying different hand muscles is outlined. Motor neurons innervating intrinsic muscles appear to have relatively independent lines of input from supraspinal centres whereas substantial divergence of descending input is seen across motor nuclei supplying extrinsic hand muscles. The functional significance of such differential organizations of descending inputs for the control of hand movements is discussed.
运动单位既是机械装置，也是通过其实施运动行为的神经处理的最后阶段。因此，了解供应手指肌肉的运动单位的神经传入的收缩特性和组织对于理解人类手的各种运动功能的控制策略至关重要。在这篇简要的综述中，描述了人类手部肌肉中运动单位的基本收缩特性。手部运动单位不易被归类为在猫腓肠肌中建立的经典生理学类型。此外，还概述了向供应不同手部肌肉的运动核下行突触传入的分布。支配内在肌肉的运动神经元似乎来自中枢神经系统的传入具有相对独立的线路，而供应外在手部肌肉的运动核的下行传入则有很大的分歧。对于手部运动控制，讨论了这种下行传入的差异组织的功能意义。
