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

Options

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

Explanation

To solve the question regarding the correct description of a certain part of the normal human skeleton, we can analyze each option provided in the question. Here’s a step-by-step breakdown:

### Step 1: Understand the Components of the Human Skeleton
The human skeleton consists of various bones and joints. It is important to know the types of joints (fibrous, cartilaginous, and synovial) and the specific bones that articulate with each other.

### Step 2: Analyze the Statements
1. **Parietal and Temporal Bone Connection**: The parietal bone and the temporal bone of the skull are joined by a fibrous joint known as a suture. This statement is correct.

2. **First Vertebra Description**: The first vertebra (atlas) does articulate with the occipital condyles of the skull, but it is not the axis. The axis is the second vertebra. This statement is incorrect.

3. **Floating Ribs**: The 9th and 10th ribs are not floating ribs; the 11th and 12th ribs are classified as floating ribs. This statement is also incorrect.

4. **Glenoid Cavity Function**: The glenoid cavity is a depression in the scapula where the head of the humerus articulates, not the thigh bone. The thigh bone (femur) articulates with the acetabulum of the pelvis. This statement is incorrect.

### Step 3: Conclusion
Based on the analysis, the correct description is the first statement regarding the parietal and temporal bones being joined by a fibrous joint (suture). Therefore, the correct answer is **A**.

### Final Answer
The correct description of a certain part of a normal human skeleton is that the parietal bone and the temporal bone of the skull are joined by a fibrous joint (suture).

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