What structure is indicated by the yellow arrow in the nerve diagram?

What structure is indicated by the yellow arrow in the nerve diagram?

• A. Node of Ranvier
• B. Myelinated axon
• C. Clefts of Schmidt-Lanterman
• D. Epineurium

Answer: (A)

A Node of Ranvier is the gap between the myelin segments along a myelinated axon. This unmyelinated stretch exposes the axon and hosts a high density of voltage-gated sodium channels, enabling rapid, saltatory conduction where the action potential hops from node to node, speeding neural signaling. The other options don’t fit because a myelinated axon describes the insulated segments with myelin, not the gap; Schmidt-Lanterman clefts are small cytoplasmic channels within the myelin, not the distinct interruption between myelin sheaths; and the epineurium is the outer connective tissue covering the entire nerve, not a feature along the axon.

A Node of Ranvier is the gap between the myelin segments along a myelinated axon. This unmyelinated stretch exposes the axon and hosts a high density of voltage-gated sodium channels, enabling rapid, saltatory conduction where the action potential hops from node to node, speeding neural signaling. The other options don’t fit because a myelinated axon describes the insulated segments with myelin, not the gap; Schmidt-Lanterman clefts are small cytoplasmic channels within the myelin, not the distinct interruption between myelin sheaths; and the epineurium is the outer connective tissue covering the entire nerve, not a feature along the axon.