Which one of the following statements is true

Options

A. Head of humerus bone articulates with acetabulum of pectoral girdle.
B. Head of humerus bone articulates with glenoid cavity of pectoral girdle.
C. Head of humerus bone articulates with a cavity called acetabulum of pelvic girdle.
D. Head of humerus bone articulates with a glenoid cavity of pelvic girdle.

Answer

To determine which statement is true regarding the articulation of the head of the humerus bone, we can analyze each of the provided statements step by step.

### Step 1: Understand the anatomy involved
- The humerus is the long bone in the upper arm that connects the shoulder to the elbow.
- The head of the humerus is the rounded part at the proximal end that fits into a socket to form a joint.

### Step 2: Identify the relevant girdles
- There are two types of girdles mentioned: the pectoral girdle (shoulder girdle) and the pelvic girdle (hip girdle).
- The pectoral girdle connects the upper limbs to the body, while the pelvic girdle connects the lower limbs.

### Step 3: Analyze each statement
1. **Head of humerus bone articulates with acetabulum of pectoral girdle.**
- **False**: The acetabulum is part of the pelvic girdle, not the pectoral girdle.

2. **Head of humerus bone articulates with glenoid cavity of pectoral girdle.**
- **True**: The head of the humerus fits into the glenoid cavity of the scapula (shoulder blade), forming the shoulder joint.

3. **Head of humerus bone articulates with a cavity called acetabulum of pelvic girdle.**
- **False**: The head of the humerus does not articulate with the acetabulum; it is part of the pelvic girdle.

4. **Head of humerus bone articulates with a glenoid cavity of pectoral pelvic girdle.**
- **False**: The term "pectoral pelvic girdle" is incorrect as these are two separate structures.

### Step 4: Conclusion
- The only true statement is: **Head of humerus bone articulates with glenoid cavity of pectoral girdle.**

### Summary of the Solution:
The correct answer is that the head of the humerus bone articulates with the glenoid cavity of the pectoral girdle.

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