Contraction of diaphragm increases the volume of thoracic chamber in the

Options

A. Dorso-ventral axis
B. Antero-posterior axis
C. Dorso-posterior axis
D. Antero-ventral axis

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the effect of diaphragm contraction on the volume of the thoracic chamber and which axis this increase in volume occurs.

2. **Role of the Diaphragm**: The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity. When it contracts, it moves downward, which increases the volume of the thoracic cavity.

3. **Effect on Thoracic Volume**: The contraction of the diaphragm leads to an increase in the volume of the thoracic chamber. This is because the diaphragm's downward movement creates more space in the thoracic cavity.

4. **Understanding the Axes**: The thoracic cavity can expand in different axes:
- **Dorsoventral Axis**: Refers to the front (ventral) and back (dorsal) dimensions.
- **Anterior-Posterior Axis**: Refers to the front (anterior) and back (posterior) dimensions.
- **Dorso-Posterior Axis**: This is not a standard term used in anatomy.
- **Anterior-Ventral Axis**: This is also not a standard term.

5. **Identifying the Correct Axis**: The contraction of the diaphragm primarily increases the volume of the thoracic chamber in the anterior-posterior axis. This is because as the diaphragm contracts and moves downwards, it increases the space from the front to the back of the thoracic cavity.

6. **Conclusion**: Therefore, the correct answer to the question is that the contraction of the diaphragm increases the volume of the thoracic chamber in the **anterior-posterior axis**.

### Final Answer:
The contraction of the diaphragm increases the volume of the thoracic chamber in the **anterior-posterior axis**.