Question

multiple choice 2 points
nerve fibers are insulated from one another by _______
blood vessels
fascicles
perineurium
endoneurium
epineurium

Explanation:

Analyze nerve connective tissue layers

Using the Mixed Nerve Structure knowledge point, we examine the protective connective tissue coverings surrounding peripheral nerves:

• Epineurium: The outermost layer of dense irregular connective tissue that encloses the entire peripheral nerve.
• Perineurium: The middle layer of connective tissue that wraps groups of nerve fibers into bundles called fascicles.
• Endoneurium: A delicate layer of loose connective tissue that surrounds each individual nerve fiber (axon) and its associated Schwann cell, providing electrical insulation from neighboring fibers.

Evaluate the given options

• blood vessels: Provide nourishment but do not serve as individual insulation layers.
• fascicles: Bundles of nerve fibers, not the insulating material itself.
• perineurium: Insulates and protects bundles (fascicles), not individual fibers from one another.
• endoneurium: Directly surrounds and insulates individual nerve fibers from one another.
• epineurium: Surrounds the entire nerve, not individual fibers.

Therefore, the endoneurium is the specific layer that insulates individual nerve fibers from one another.

Answer:

• blood vessels
• fascicles
• perineurium
• endoneurium (Correct answer)
• epineurium