What kind of local anesthesia is deposited near the larger terminal nerve branches so that the anesthetized area will be circumscribed?

• A. Field block
• B. Local infiltration
• C. Nerve block
• D. Topical anesthesia

Answer: (A)

Field block is the technique used when you want the anesthesia to cover a defined region that’s supplied by the larger terminal branches of a nerve. By depositing the local anesthetic near these branches, the drug diffuses to block the nerve fibers as they radiate to the tissues in that area. The result is a circumscribed zone of numbness that follows the boundaries set by those terminal branches and their tissue distribution.

This differs from local infiltration, which targets a very small area by injecting directly into the tissue at the site of the procedure, relying on diffusion to spread only a short distance. It also differs from a nerve block, where the anesthetic is placed near a main nerve trunk to block all branches along that path, often producing a broader or less precisely bounded field. Topical anesthesia is simply applied to the surface mucosa and does not produce a true field blockade of deeper tissues.