C57BL/6 小鼠胫骨前肌和趾长伸肌肌梭解剖学分析

Objective To locate the distribution of muscle spindles in tibialis anterior (TA) and extensor digitorum longus muscle (EDL) and the anchoring mode of muscle spindles in skeletal muscles, and perform statistics analysis of their morphological character by anatomical parameters. Methods Five adult wild type C57BL/6 mice were sacrificed, and TA and EDL were dissected and frozen with improved ultra-low temperature cryopreservation technology avoiding myofibers damaged by possible ice crystal. Continuous frozen transections were obtained and operated by HE staining, followed by microimaging to spot the muscle spindles location. Some parameters including regions length and cross section area (CSA) of muscle spindles were noticed for the discovery of some general characteristics of spindles by statistics. Results For TA and EDL, the scattered characters of muscle spindles were distributed as follows: the spindles were located at the upper third of the mid-belly of both TA and EDL from caudal to rostral position, while near the enter point to muscle of the deep peroneal nerve in dorsal-ventral orientation. The peripheral of muscle spindles anchored to extrafusal fibers to hold in the muscle. And in term of length, region A, connected with sensory nerve ending, demonstrated a significant correlation with region B, which located at the poles of region A and twined by motor nerve ending (correlation index = 0. 75) when considering the muscle spindles with four intrafusal fibers only. And no correlation was discovered in any others pairwise parameters. Conclusion The scattered diagram of muscle spindles in TA and EDL of C57BL/6 mice might provide anatomic basis for evaluation of lower limb motor function, especially for the spinal cord injury and recovery research. And the correlationship between the length of region A and B might improve exploring the variability of electrophysiological characters.