Which of the following statement is incorrect with respect to the histology of alimentary canal ?

Options

A. Serosa is the outermost layer which is made up of a thin mesothelium with some connective tissue.
B. Muscular is is formed by smooth muscles usually arranged into an inner longitudinal layer and outer circular layer.
C. Submucosal layer is formed of loose connective tissue.
D. An oblique muscle layer may by present in the stomach.

Answer

To solve the question regarding which statement is incorrect with respect to the histology of the alimentary canal, we will analyze each option based on our understanding of the structure of the alimentary canal.

### Step-by-Step Solution:

1. **Understand the Layers of the Alimentary Canal**:
- The alimentary canal is composed of four main layers:
- **Serosa** (outermost layer)
- **Muscularis** (second layer)
- **Submucosa** (third layer)
- **Mucosa** (innermost layer)

2. **Analyze the Statements**:
- **Statement 1**: "Serosa is the outermost layer that is made up of a thin mesothelium."
- This statement is **correct**. The serosa is indeed the outermost layer and consists of a thin layer of mesothelium along with connective tissue.

- **Statement 2**: "Muscularis is formed by smooth muscles usually arranged into an inner longitudinal and outer circular layer."
- This statement is **incorrect**. The muscularis layer is made up of smooth muscle arranged in an **inner circular** layer and an **outer longitudinal** layer, not the other way around.

- **Statement 3**: "Submucosal layer is formed of loose connective tissue which consists of nerves and blood vessels and lymph vessels."
- This statement is **correct**. The submucosa is indeed made of loose connective tissue and contains nerves, blood vessels, and lymph vessels.

- **Statement 4**: "An oblique muscle layer may be present in the stomach."
- This statement is **correct**. The muscularis layer in the stomach does include an additional oblique layer of muscle.

3. **Identify the Incorrect Statement**:
- From the analysis, we can see that **Statement 2** is incorrect because it misstates the arrangement of the muscle layers in the muscularis.

### Conclusion:
The incorrect statement regarding the histology of the alimentary canal is:
**"Muscularis is formed by smooth muscles usually arranged into an inner longitudinal and outer circular layer."**