Final answer:
The nerve block injection technique offers the longest duration of anesthesia due to a more concentrated and sustained administration of the anesthetic around the nerves, leading to slower systemic absorption.
Step-by-step explanation:
The question pertains to the duration of anesthesia provided by different injection techniques. Among the techniques listed - field block, nerve block, and infiltration - the nerve block typically provides the longest duration of anesthesia. A nerve block is a procedure where an injectable anesthetic is administered directly around a nerve or a group of nerves to block pain from a specific area of the body. This technique results in a more concentrated and targeted effect, often offering a longer duration of anesthesia compared to a field block or infiltration, where the rate of systemic absorption of the anesthetic is typically faster, reducing the duration of the anesthetic effect.
Local anesthetics like lidocaine work by blocking the sodium channels on nerve cells, which prevents the initiation and transmission of nerve impulses. Consequently, this action leads to a reversible loss of sensation and muscle function in the targeted area. The ability to maintain this effect over a period is dependent on the type of injection technique used, with nerve blocks usually providing a more sustained duration due to slower absorption and distribution of the anesthetic agent.