Brown Nicholas A T, Kawcak Christopher E, McIlwraith C Wayne, Pandy Marcus G
Department of Biomedical Engineering, The University of Texas, Austin, Texas 78712, USA.
J Morphol. 2003 Oct;258(1):106-14. doi: 10.1002/jmor.10113.
Articular injuries in athletic horses are associated with large forces from ground impact and from muscular contraction. To accurately and noninvasively predict muscle and joint contact forces, a detailed model of musculoskeletal geometry and muscle architecture is required. Moreover, muscle architectural data can increase our understanding of the relationship between muscle structure and function in the equine distal forelimb. Muscle architectural data were collected from seven limbs obtained from five thoroughbred and thoroughbred-cross horses. Muscle belly rest length, tendon rest length, muscle volume, muscle fiber length, and pennation angle were measured for nine distal forelimb muscles. Physiological cross-sectional area (PCSA) was determined from muscle volume and muscle fiber length. The superficial and deep digital flexor muscles displayed markedly different muscle volumes (227 and 656 cm3, respectively), but their PCSAs were very similar due to a significant difference in muscle fiber length (i.e., the superficial digital flexor muscle had very short fibers, while those of the deep digital flexor muscle were relatively long). The ulnaris lateralis and flexor carpi ulnaris muscles had short fibers (17.4 and 18.3 mm, respectively). These actuators were strong (peak isometric force, Fmax=5,814 and 4,017 N, respectively) and stiff (tendon rest length to muscle fiber length, LT:LMF=5.3 and 2.1, respectively), and are probably well adapted to stabilizing the carpus during the stance phase of gait. In contrast, the flexor carpi radialis muscle displayed long fibers (89.7 mm), low peak isometric force (Fmax=555 N), and high stiffness (LT:LMF=1.6). Due to its long fibers and low Fmax, flexor carpi radialis appears to be better adapted to flexion and extension of the limb during the swing phase of gait than to stabilization of the carpus during stance. Including muscle architectural parameters in a musculoskeletal model of the equine distal forelimb may lead to more realistic estimates not only of the magnitudes of muscle forces, but also of the distribution of forces among the muscles crossing any given joint.
运动马匹的关节损伤与地面冲击和肌肉收缩产生的巨大力量有关。为了准确且无创地预测肌肉和关节接触力，需要一个详细的肌肉骨骼几何结构和肌肉结构模型。此外，肌肉结构数据可以增进我们对马前肢远端肌肉结构与功能之间关系的理解。从五匹纯种马和纯种杂交马的七个前肢采集了肌肉结构数据。测量了九条前肢远端肌肉的肌腹静息长度、肌腱静息长度、肌肉体积、肌纤维长度和羽状角。根据肌肉体积和肌纤维长度确定生理横截面积（PCSA）。浅屈指肌和深屈指肌的肌肉体积明显不同（分别为227和656 cm³），但由于肌纤维长度存在显著差异，它们的PCSA非常相似（即浅屈指肌的纤维非常短，而深屈指肌的纤维相对较长）。尺外侧肌和尺侧腕屈肌的纤维较短（分别为17.4和18.3 mm）。这些肌肉力量强大（等长收缩峰值力，Fmax分别为5814和4017 N）且僵硬（肌腱静息长度与肌纤维长度之比，LT:LMF分别为5.3和2.1），可能非常适合在步态站立期稳定腕关节。相比之下，桡侧腕屈肌的纤维较长（89.7 mm），等长收缩峰值力较低（Fmax = 555 N），且刚度较高（LT:LMF = 1.6）。由于其纤维较长且Fmax较低，桡侧腕屈肌似乎更适合在步态摆动期使肢体屈伸，而不是在站立期稳定腕关节。将肌肉结构参数纳入马前肢远端的肌肉骨骼模型中，不仅可能使对肌肉力量大小的估计更加现实，而且可能使对跨越任何给定关节的肌肉之间力的分布的估计更加现实。
