The endoneurium is best described as the tissue that surrounds which of the following?

The endoneurium is best described as the tissue that surrounds which of the following?

• A. It surrounds the nerve root
• B. It surrounds bundles of fascicles
• C. It surrounds the entire nerve trunk
• D. It surrounds individual axons

Answer: (D)

Endoneurium is the delicate connective tissue that directly wraps each individual axon (and its myelin segment) within a nerve. It sits inside the larger fascicle, surrounding the Schwann-cell–axon unit and housing small blood vessels and supporting cells that help maintain the axon’s environment. The layer that encloses a bundle of these axons is the perineurium, and the outermost layer that covers the entire nerve trunk is the epineurium. So the endoneurium specifically surrounds individual axons, not nerve roots, fascicle bundles, or the whole nerve.

Endoneurium is the delicate connective tissue that directly wraps each individual axon (and its myelin segment) within a nerve. It sits inside the larger fascicle, surrounding the Schwann-cell–axon unit and housing small blood vessels and supporting cells that help maintain the axon’s environment. The layer that encloses a bundle of these axons is the perineurium, and the outermost layer that covers the entire nerve trunk is the epineurium. So the endoneurium specifically surrounds individual axons, not nerve roots, fascicle bundles, or the whole nerve.