Which layer surrounds bundles of axons?

• A. Endoneurium
• B. Epineurium
• C. Perineurium
• D. Meninges

Answer: (C)

The key idea here is how a peripheral nerve is organized into protective coverings for its fibers. Axons are grouped into bundles called fascicles. The layer that wraps each of these bundles is the perineurium. It forms a protective sheath around a fascicle and helps create a blood–nerve barrier to guard the fibers inside.

In comparison, the endoneurium wraps around individual axons within a fascicle, providing support to each single fiber. The epineurium is the outermost layer that encloses the entire nerve, including all fascicles and the surrounding blood vessels and fat. The meninges aren’t part of peripheral nerves—they are the protective coverings of the brain and spinal cord.