The alimentary canal of a deceased individual was cut transversely for examination of the arrangement of layers from outside to inside. Select the correct sequence of arrangement for the layers examined.

Options

A. Serosa `rarr` Longitudinal muscles `rarr` Circular muscles `rarr` Mucosa `rarr` Submucosa
B. Mucosa `rarr` Submucosa`rarr` Circular muscles `rarr`Longitudinal muscle `rarr`Serosa
C. Serosa `rarr` Longitudinal muscles `rarr` Circular muscles `rarr` Submucosa `rarr` Mucosa
D. Serosa `rarr` Longitudinal muscles `rarr` Oblique muscles `rarr` Circular muscles `rarr` Submucosa `rarr` Mucosa

Answer

To determine the correct sequence of layers of the alimentary canal from outside to inside, we need to understand the structure of the canal. The alimentary canal is composed of four main layers, which are arranged in a specific order. Here’s the step-by-step solution:

### Step-by-Step Solution:

1. **Identify the Outermost Layer**:
- The outermost layer of the alimentary canal is called the **serosa**. This is a thin layer of mesothelium that covers the outer surface of the canal.

2. **Next Layer Inward**:
- Beneath the serosa is the **muscularis layer**. This layer consists of smooth muscle and is responsible for the peristaltic movements of the digestive tract. It typically has two sub-layers: the outer layer of longitudinal muscles and the inner layer of circular muscles.

3. **Third Layer**:
- The third layer is the **submucosa**. This layer contains loose connective tissue and is rich in blood vessels, nerves, and lymphatics. It serves as a supportive layer for the mucosa and contains the nerve plexus that regulates digestive activities.

4. **Innermost Layer**:
- The innermost layer is called the **mucosa**. This layer is involved in the secretion and absorption processes. It often has modifications such as folds (rugae in the stomach) or projections (villi in the small intestine) to increase the surface area for digestion and absorption.

5. **Final Arrangement**:
- Putting it all together, the correct sequence of the layers from outside to inside is:
- **Serosa**
- **Muscularis**
- **Submucosa**
- **Mucosa**

### Correct Answer:
The correct sequence of arrangement for the layers examined is:
1. Serosa
2. Muscularis
3. Submucosa
4. Mucosa