The incorrectly matched pair is

Options

A. Cerpora quadrigemina - canal that passes through midbrain
B. Corpora quadrigemina - Four rounded swellings present on ventral portion of midbrain
C. Cerebrum - Very convoluted surface
D. Medulla oblongata - Controls gastric secretions.

Answer

To determine the incorrectly matched pair from the given options, we will analyze each pair one by one.

### Step-by-Step Solution:

1. **Identify the First Pair: Cerebral Aqueduct**
- The cerebral aqueduct is a canal that passes through the midbrain, connecting the third and fourth ventricles.
- This description is accurate. Therefore, this pair is correctly matched.

2. **Identify the Second Pair: Corpora Quadrigemina**
- The corpora quadrigemina consists of four rounded swellings located in the midbrain.
- However, the transcript states that these structures are located on the dorsal (back) side of the midbrain, not the ventral (front) side as mentioned in the pair.
- This makes this pair incorrectly matched.

3. **Identify the Third Pair: Cerebrum**
- The cerebrum is indeed convoluted, with grooves (sulci) and ridges (gyri) that allow it to fit into the cranial cavity.
- This description is correct, so this pair is also correctly matched.

4. **Identify the Fourth Pair: Medulla Oblongata**
- The medulla oblongata is a part of the brain that controls various autonomic functions, including gastric secretion.
- This description is accurate, making this pair correctly matched.

### Conclusion:
The only incorrectly matched pair is the second one: **Corpora Quadrigemina** (which is incorrectly stated to be on the ventral portion of the midbrain).

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