Which of the following is not correct the thoracic chamber in humans ?

Options

A. It is an air tight chamber is which lungs are situated.
B. It is formed ventrally by sternum and dorsally by ribs.
C. It is formed on the lower side by the dome shaped diaphragm.
D. Both (A) and (C)

Answer

To determine which statement about the thoracic chamber in humans is not correct, we need to analyze each of the given options:

1. **It is an airtight chamber in which lungs are situated.**
- The thoracic cavity is indeed an airtight chamber that contains the lungs. This statement is correct.

2. **It is formed ventrally by sternum and dorsally by ribs.**
- This statement is incorrect. The thoracic cavity is formed ventrally (front) by the sternum, but dorsally (back) it is formed by the vertebral column, not the ribs. The ribs form the lateral walls of the thoracic cavity. Therefore, this statement is not correct.

3. **It is formed on the lower side by the dome-shaped diaphragm.**
- The diaphragm is a dome-shaped muscle that forms the lower boundary of the thoracic cavity. This statement is correct.

4. **Both A and C.**
- This option suggests that both statements A and C are incorrect. However, since both A and C are correct, this option is also incorrect.

Based on the analysis, the statement that is not correct about the thoracic chamber in humans is:
**"It is formed ventrally by sternum and dorsally by ribs."**