The yellow arrow points to which outer covering of the nerve?

The yellow arrow points to which outer covering of the nerve?

• A. Epineurium
• B. Perineurium
• C. Nodes of Ranvier
• D. Clefts of Schmidt-Lanterman

Answer: (A)

The outer covering of a peripheral nerve is the epineurium. This tough, fibrous sheath surrounds the entire nerve and provides protection while housing the blood vessels that supply the nerve. Inside it, the nerve is organized into fascicles wrapped by the perineurium, with individual axons encased by the endoneurium. Nodes of Ranvier are gaps along the myelin sheath of an axon, not nerve coverings, and Schmidt-Lanterman clefts are cytoplasmic channels within the myelin. So the epineurium is the correct outermost layer.

The outer covering of a peripheral nerve is the epineurium. This tough, fibrous sheath surrounds the entire nerve and provides protection while housing the blood vessels that supply the nerve. Inside it, the nerve is organized into fascicles wrapped by the perineurium, with individual axons encased by the endoneurium. Nodes of Ranvier are gaps along the myelin sheath of an axon, not nerve coverings, and Schmidt-Lanterman clefts are cytoplasmic channels within the myelin. So the epineurium is the correct outermost layer.