M.C. nerve used for monitoring during anaesthesia
**Core Concept**
The MC nerve is a motor nerve that is commonly used as a monitor during anesthesia to assess the depth of neuromuscular blockade. It is a mixed nerve that carries both motor and sensory fibers, but its motor function is primarily used for monitoring purposes.
**Why the Correct Answer is Right**
The correct answer is the median nerve (C6-C8), which is a mixed nerve that supplies the muscles of the anterior forearm and hand. When the median nerve is stimulated, it can cause the thumb to flex, which can be used to monitor the depth of neuromuscular blockade. This is because the median nerve is easily accessible and its motor function is well understood. The train-of-four (TOF) stimulation technique is commonly used to assess the degree of neuromuscular blockade by measuring the twitch height of the thumb.
**Why Each Wrong Option is Incorrect**
* **Option A:** The ulnar nerve is a mixed nerve that supplies the muscles of the forearm and hand, but it is not typically used for monitoring during anesthesia.
* **Option B:** The radial nerve is a mixed nerve that supplies the muscles of the posterior arm and forearm, but it is not typically used for monitoring during anesthesia.
* **Option D:** The musculocutaneous nerve is a pure motor nerve that supplies the biceps brachii muscle, but it is not typically used for monitoring during anesthesia.
**Clinical Pearl / High-Yield Fact**
When using the median nerve for monitoring during anesthesia, it is essential to use the train-of-four (TOF) stimulation technique to assess the degree of neuromuscular blockade. This involves delivering four rapid electrical stimuli to the median nerve and measuring the twitch height of the thumb.
**Correct Answer:** C. Median nerve.