**Question:** In spinal anaesthesia, the drug is deposited between -

A. Intervertebral spaces
B. Epineurium and endoneurium
C. Intrathecal space
D. Intracranial space

**Core Concept:**

Spinal anaesthesia is a technique used to induce local anesthesia in the body by injecting a drug directly into the spinal canal, also known as the intrathecal space. This space surrounds the spinal cord and nerve roots, allowing the drug to spread and block sensory and motor function in a specific region or even the entire body based on the dose and type of drug used.

**Why the Correct Answer is Right:**

In spinal anaesthesia, the drug is deposited specifically in the **C**. Intrathecal space. This space is located between the arachnoid mater and the pia mater, surrounding the spinal cord and nerve roots. When the drug is injected into this space, it spreads to cover a specific segment or even the entire spinal cord, depending on the dosage and type of drug.

**Why Each Wrong Option is Incorrect:**

A. **Intervertebral spaces**: These spaces are found between the vertebrae and are not related to spinal anesthesia. The drug would not effectively spread to cover the spinal cord in this location.

B. **Epineurium and endoneurium**: These are layers of connective tissue surrounding the nerves. They are unrelated to spinal anesthesia, which targets the intrathecal space around the spinal cord.

D. **Intracranial space**: This refers to the space within the skull containing the brain and brainstem, which is unrelated to spinal anesthesia. The drug would have no effect on spinal function if deposited in this space.

**Clinical Pearl:**

Understanding the correct placement of the drug in spinal anesthesia is essential for effective anesthesia. The intrathecal space, located between the arachnoid and pia mater, allows the drug to spread and block sensory and motor function in a targeted manner, depending on the drug and dosage chosen.