**Question:** M.C. nerve used for monitoring during anaesthesia –

A. Cervical spinal nerves (C1-C2)
B. Tracheal auscultation
C. Electrocardiogram (ECG)
D. Fetal heart rate monitoring

**Core Concept:** Monitoring during anaesthesia is essential for ensuring patient safety and detecting complications. Key monitoring parameters include assessing cardiovascular, respiratory, and neurological functions.

**Why the Correct Answer is Right:** Monitoring cervical spinal nerves (C1-C2) during anaesthesia helps assess the phrenic nerve function. The phrenic nerve originates from C3-C5 and innervates the diaphragm, which is crucial for respiration. Monitoring its function ensures that the patient's breathing remains unimpaired during anaesthesia.

**Why Each Wrong Option is Incorrect:**

A. Tracheal auscultation is a method to assess lung sounds and air entry, not specifically related to monitoring a nerve during anaesthesia.

B. ECG monitoring is important for cardiac function, not nerve monitoring. ECG detects changes in heart rate and rhythm, which can be influenced by anaesthesia, but not directly related to monitoring a specific nerve.

C. Electrocardiogram (ECG) is related to cardiac function, not monitoring a specific nerve during anaesthesia.

D. Fetal heart rate monitoring is relevant for obstetric patients and not applicable to the general anaesthesia scenario.

**Clinical Pearl:** Phrenic nerve monitoring can be performed using a nerve stimulator or a peripheral nerve stimulator. These devices can provide real-time feedback on the nerve function during anaesthesia, ensuring patient safety and preventing complications related to compromised respiratory function.

**Correct Answer:** A. Cervical spinal nerves (C3-C5)