Research Division, Shriners Hospital for Children, Portland, OR 97239, USA.
Dev Cell. 2013 Sep 16;26(5):544-51. doi: 10.1016/j.devcel.2013.08.007.
The muscles that govern hand motion are composed of extrinsic muscles that reside within the forearm and intrinsic muscles that reside within the hand. We find that the extrinsic muscles of the flexor digitorum superficialis (FDS) first differentiate as intrinsic muscles within the hand and then relocate as myofibers to their final position in the arm. This remarkable translocation of differentiated myofibers across a joint is dependent on muscle contraction and muscle-tendon attachment. Interestingly, the intrinsic flexor digitorum brevis (FDB) muscles of the foot are identical to the FDS in tendon pattern and delayed developmental timing but undergo limited muscle translocation, providing strong support for evolutionary homology between the FDS and FDB muscles. We propose that the intrinsic FDB pattern represents the original tetrapod limb and that translocation of the muscles to form the FDS is a mammalian evolutionary addition.
控制手部运动的肌肉由位于前臂的外在肌肉和位于手部的内在肌肉组成。我们发现，手指屈肌（FDS）的外在肌肉首先在手部分化为内在肌肉，然后作为肌纤维重新定位到手臂的最终位置。这种跨越关节的分化肌纤维的显著移位依赖于肌肉收缩和肌肉-肌腱连接。有趣的是，足部的内在指浅屈肌（FDB）肌肉在肌腱模式和延迟发育时间上与 FDS 相同，但肌肉移位有限，为 FDS 和 FDB 肌肉之间的进化同源性提供了有力支持。我们提出，内在的 FDB 模式代表了原始的四足动物肢体，而肌肉的移位形成 FDS 是哺乳动物进化的附加物。
