Peripheral nerve epineurium

The peripheral nerve epineurium is the outermost layer of dense irregular connective tissue that surrounds a peripheral nerve, providing essential structural integrity and protection (StatPearls, 2023). It is primarily composed of collagen fibers (mostly Type I and III), fibroblasts, and elastic fibers, and it houses the vasa nervorum, which are the blood vessels supplying the nerve (PubMed, 2021). In clinical pharmacology, the epineurium is not a molecular target but rather a critical physiological barrier that limits the rate and extent of drug diffusion, such as local anesthetics, to the underlying axons (Journal of Anatomy, 2018). Pathologically, the epineurium can undergo fibrosis or thickening in response to chronic compression or trauma, contributing to conditions like carpal tunnel syndrome or peripheral neuropathy (NIH, 2022). Understanding its composition is vital for developing effective nerve-targeted drug delivery systems and surgical techniques for nerve regeneration (ScienceDirect, 2020). Furthermore, the epineurium is a key site for the placement of neural interfaces and electrodes, where its mechanical properties influence the stability and safety of the device (PubMed, 2019).

Other names

EpineuriumNerve sheathOuter nerve coveringPeripheral nerve connective tissuePeripheral nerve epineurial components

Acts as a physical and diffusion barrier for drug penetration into the endoneurium; enzymatic degradation of matrix components (e.g., by hyaluronidase) can facilitate drug delivery.