**Question:** Structures not removed in radical neck dissection

A. X nerve
B. X1 nerve
C. Tail of parotid
D. Parotid and post-auricular nerve

**Core Concept:** Radical neck dissection is a surgical procedure used in the treatment of head and neck cancers that involves removing lymph nodes, blood vessels, and muscles from a specific region of the neck. The goal is to reduce the risk of cancer spread and improve survival rates.

**Why the Correct Answer is Right:** In a radical neck dissection, the following structures are typically spared:

1. **Option A: X nerve (Axillary nerve)** - The X nerve, also known as the cervical plexus, is responsible for the innervation to the skin and subcutaneous tissues of the anterior neck, axilla, and upper limb. It is a crucial structure and must be preserved to avoid postoperative deficits in these areas.

2. **Option B: X1 nerve (Axillary nerve)** - The X1 nerve is a branch of the X nerve that controls the skin and subcutaneous tissues of the anterior neck and axilla. Similar to the X nerve, preserving the X1 nerve is essential to prevent post-operative deficits in these regions.

3. **Option C: Tail of parotid (Salivary gland)** - The tail of the parotid gland is a crucial component of the procedure, as removing it may lead to significant complications such as xerostomia (dry mouth), which is a severe side effect of parotidectomy.

4. **Option D: Parotid and post-auricular nerve** - The parotid gland is essential for saliva production, and removing it may result in severe complications like xerostomia. The post-auricular nerve, also known as the posterior auricular nerve, provides sensation to the posterior auricle (earlobe) and should not be removed to prevent post-operative deficits in this area.

**Why Each Wrong Answer is Incorrect:**

5. **Option A: X nerve (Axillary nerve)** - Although the X nerve provides innervation to the anterior neck and axilla, removing it is not essential in radical neck dissection. The preservation of the X nerve ensures motor function and sensation in these areas post-operatively.

6. **Option B: X1 nerve (Axillary nerve branch)** - As mentioned earlier, preserving the X1 nerve is crucial to maintain motor function and sensation in the anterior neck and axilla.

7. **Option C: Tail of parotid gland** - Although the tail of the parotid gland is essential, removing it is not necessary in radical neck dissection. Preserving the gland helps avoid complications like xerostomia (dry mouth) and xerostomia (dry mouth) following surgery.

8. **Option D: Post-auricular nerve (Posterior auricular nerve)** - Although preserving the post-auricular nerve is important for earlobe sensation, removing it is not essential in a radical neck dissection. The primary focus is on removing the affected lymph nodes and vessels, rather than solely preserving specific nerves.

9. **Option C: T