The thick part of the choroid layer forms

Options

A. cornea
B. iris
C. ciliary body
D. ganglion

Answer

To solve the question regarding what the thick part of the choroid layer forms, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Layers of the Eye**:
- The eye consists of three main layers: the outermost layer (sclera), the middle layer (choroid), and the innermost layer (retina).

2. **Identify the Choroid Layer**:
- The choroid layer is the middle layer of the eye and is composed of loose connective tissue. It contains many blood vessels and pigment cells, giving it a bluish appearance.

3. **Examine the Structure of the Choroid**:
- The choroid is thin over the posterior two-thirds of the eyeball and thickens towards the anterior part.

4. **Determine What the Thick Part Forms**:
- The thick part of the choroid layer forms the ciliary body, which is involved in the accommodation of the lens and the production of aqueous humor.

5. **Eliminate Incorrect Options**:
- Cornea: This is a separate layer of the eye and does not form from the choroid.
- Arreus: This term does not relate to the anatomy of the eye.
- Ganglion: This refers to a collection of nerve cell bodies and is not a structure formed by the choroid.

6. **Conclude the Correct Answer**:
- Based on the above analysis, the thick part of the choroid layer forms the ciliary body.

### Final Answer:
The thick part of the choroid layer forms the **ciliary body**.

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