肌束膜（英语：perimysium）是一层把肌纤维组合成束（捆）即肌束（muscle fascicle）的结缔组织鞘（套）。

肌肉生理学新近研究发现肌束膜在“侧收缩运动”（lateral contractile movement）中起作用。这个假说肌束膜胶**络的总体组织结构，以及连续性和相异性，尚未在所有肌肉中得到充分观察和描述。

Perimysium is a sheath of connective tissue that groups muscle fibers into bundles (anywhere between 10 to 100 or more) or fascicles.

Recent advances in muscle physiology suggest that the perimysium plays a role in transmitting lateral contractile movements. This hypothesis is strongly supported in one exhibition of the existence of "Perimysial Junctional Plates" in ungulate Flexor carpi radialis muscles constructed by E Passerieux. The overall comprehensive organization of the perimysium collagen network, as well as its continuity and disparateness, however, have still not been observed and described thoroughly everywhere within the muscle.