Which one of the following is correct description of a certain part of a normal human skeleton ?

Options

A. First vertebra is axis which articulates with the occipital condyles.
B. The `9^(th)` and `10^(th)` pairs of ribs are called the floating ribs.
C. Glenoid cavity is a depression to which the thigh bone articulates.
D. Parietal bone and the temporal bone of the skull are joined by fibrous joint.

Answer

To solve the question regarding the correct description of a certain part of a normal human skeleton, we will analyze each of the provided statements step by step.

### Step 1: Analyze the First Statement
- **Statement**: "First vertebra axis which articulates with the occipital condyles."
- **Analysis**: The first vertebra is known as the atlas, not the axis. The atlas articulates with the occipital condyles of the skull. Therefore, this statement is incorrect.

### Step 2: Analyze the Second Statement
- **Statement**: "The ninth and the tenth pair of ribs are called floating ribs."
- **Analysis**: Floating ribs are actually the 11th and 12th pairs of ribs, which do not attach to the sternum. The ninth and tenth pairs are known as false ribs. Therefore, this statement is also incorrect.

### Step 3: Analyze the Third Statement
- **Statement**: "Glenoid cavity is a depression to which thigh bone articulates."
- **Analysis**: The glenoid cavity is the part of the scapula where the head of the humerus (the upper arm bone) articulates, not the thigh bone. The thigh bone (femur) articulates with the acetabulum of the pelvis. Thus, this statement is incorrect.

### Step 4: Analyze the Fourth Statement
- **Statement**: "Parietal bone and the temporal bone of the skull are joined by fibrous joints."
- **Analysis**: The parietal and temporal bones are actually joined by a type of joint called a suture, which is a fibrous joint. Sutures are immovable joints found in the skull. Therefore, this statement is correct.

### Conclusion
After analyzing all the statements, the correct description of a part of the normal human skeleton is:
**The fourth statement: "Parietal bone and the temporal bone of the skull are joined by fibrous joints."**

---